According to UNESCO, three billion people across the world live below the poverty line, which is 2.50 USD or less a day. Owing to financial constraints, their main mode of communication is the radio because it’s cheaper than television or a computer.  This underlines the influence radio has on impact on the lives of communities, individuals, and nations around the globe.

Unknown to many, all radio stations don’t transmit their content in similar ways. There are those that transmit via the internet, shortwave, mediumwave, and longwave among others. The shortwave and longwave radios mainly differ on their wavelength and frequencies, which will be explained in detail below.

This article will mainly focus on shortwave and longwave radios, the commonly used devices. Read on to find out everything you need to know about the two radio types and their differences.

What is The Radio?

Before delving into the differences between shortwave and longwave radios, let’s first understand what radio means in order to get a better perspective. Radio is the method of transmitting electromagnetic energy, in the form of radio waves, from one point to the other without using wired connections. The equipment responsible for sending the radio waves is known as the transmitter while the one that receives them is the receiver. The radio tune, on the other hand, is responsible for selecting the program that you want to listen to from the existing radio signals being broadcasted.

Once the transmitter transmits the radio waves, the radio antenna on the radio receiver taps and sends them to the receiver. The receiver then makes the electrons inside it to vibrate thus recreating the original signal in the form of electronic energy.  A powerful transmitter can send radio waves to many receivers, which explains why hundreds of thousands of people across the globe can listen to the same signal at once.

What is a Radio Wave?  

In order to understand what shortwave and longwave radio are, you must first know what radio waves are because they relate. Radio waves are portioned electromagnetic energy generated by transmitters and detected by receivers. They are therefore the building blocks when it comes to radio communication.

Radio waves are the lowest portion of the electromagnetic spectrum with wavelengths ranging from 1 millimeter and 100 kilometers and a frequency between 300 GHz and 3 kHz. They travel on the surfaces of ponds in a series of peaks and valleys, which resembles those of ocean waves.

The radio waves consist of six regions that are included in the EGM spectrum as listed below in order of decreasing frequency and increasing wavelength.

  • Gamma rays: Gamma rays have a frequency range of 10 exahertz and corresponding energy above 100 keV. They have short wavelengths of 10 picometers or less.
  • X-rays: X-ray waves have a wavelength that ranges from 0.01 and 10 nanometers and a corresponding frequency of 30 petahertz up to 30 exahertz. They have shorter wavelengths to UV waves but longer than gamma rays.
  • Ultraviolet: Ultraviolet waves are made up of electromagnetic waves that have a high frequency which the human eye cannot detect as the color violet. Their wavelength ranges from 10nm and 400nm and records energy ranging from 3 eV up to 124 eV maximum.
  • Visible light: Visible light waves are produced by rotations, vibrations, and electronic transition of molecules and atoms. Their wavelength range is 0.39 and 0.75um and has a frequency of 400 to 750 THz.
  • Infrared: Infrared waves are emitted by molecules after changing their rotational and vibrational movements. They have a wavelength range of 0.74um and 1 millimeter and a frequency of 300 GHz to 1 THz.
  • Microwaves: Microwaves are waves emitted by the sun and cosmic background. They have a maximum wavelength of 1 millimeter and frequencies ranging from O.3 GHz to 300 GHz. They are referred to as micro due to their short wavelengths.

Radio waves are generated by both natural and artificial sources like lightning, cell phones, or radio towers among others. They travel at lightning speed and that is why millions of them reach the transmitter each second. They can be used in a wide array of communication fields like television stations, communication satellites, navigation systems, and radio communication among others.

What is Shortwave and Longwave Radio?

Radio spectrum mainly consists of three band branches namely; shortwave, mediumwave, and longwave. The three branches are based on their radio wave’s wavelengths and frequencies. Virtually all radio waves are electromagnetic radiations that undergo alterations whenever they pass through air, rain or objects.

In addition, their speed maintains their stability and they remain constant even in vacuum spaces. Notably, their similar characteristics with light are not that different from each other, even at shorter distances. There are millions of radio waves in the atmosphere at each particular time.

Shortwave and longwave essentially means the number of frequency and wavelength that a radio wave ranges in. Shortwave radio falls under the frequency range of 30 kHz and 278 kHz and 1500 meters wavelength. The longwave radio, on the other hand, has a frequency range of between 1.5 MHz and 30 MHz and 10 to 85 meters wavelength.

The wavelength, just like the name suggests, is the length between one wave peak to the other. The frequency, on the other hand, is the whole number of radio waves that arrive at the transmitter from the transmitter per second. The unit of measuring wave frequency is referred to as hertz represented by Hz, while wavelength is measured in feet or meters.

Differences Between Shortwave and Long Wave Radio

Now that you know what radio, radio waves, shortwave radio, and longwave radio are, let’s now focus on the differences that the two radios have. Shortwave and longwave radio are commonly used devices in the world. The two differ in different aspects of their characteristics and performance as outlined below.

1. Wavelength and Frequency

Radio wavelength and frequency are inversely proportional to each other. This means that when one increases, the other automatically decreases. For instance, a high frequency automatically means a shorter wavelength and high energy and the vice versa is true. The wavelengths and frequencies of the two types of radios are their main difference.

As indicated earlier, longwave radio has a frequency that ranges between 30 kHz and 279 kHz and covers a wavelength of over 1500 meters. Shortwave radio, on the other hand, has a frequency range of 1.5 MHz to 30 MHz and covers a median wavelength range of 10 up to 85 meters. However, shortwave radio travels long distances due to their ability to transcend through water bodies and continents, thus reaching large masses from one transmitter.

2. Movement tendencies

Radio waves mainly travel in three ways namely ground, sky, and space waves, depending on the wavelength. Ground waves follow the curves of man-made and natural resources as well as land contours. Skywaves on the other hand bounces between ionosphere and earth, which makes them excellent in long-range transmission, while sky waves travel in straight lines.

Longwave radio signals travel from one point to the other over the earth’s surface at a specific amount of power. In addition, they move in a straight line piercing through the ionosphere instead of bouncing off it. They, therefore, have the ability to cover wider terrain areas using less power.

A shortwave radio signal, on the other hand, travels in curves following the earth’s curvature while interrelating with the ionosphere. Shortwave signals travel long distances because they are skipped by air layers to long distances. This explains why shortwave radio signals can be received from anywhere across the world.

3. Antenna and Reception

For a radio station to air its program, its signals must be tapped by the antenna and guided to the receiver. That is why any radio must have an antenna responsible for tapping the surrounding radio signals. Longwave and shortwave radio differ in the size of their antenna.

Longwave radio signals are hard to tap because they travel in straight lines and along the earth’s surface. That explains why longwave radio has a longer antenna when compared to shortwave radio.  However, the long antenna disrupts their operation and ruins their aesthetic value in this era of technological advancements.

Shortwave radio signals, on the other hand, travels along the earth’s contours and curvature while interacting with the atmosphere. This, therefore, makes them readily available in the atmosphere and ionosphere making them easy to tap. That is the reason why shortwave radio has a shorter antenna thus increasing their aesthetic value and making them preferable.

4. Their Usage

As indicated earlier, shortwave radio signals travel long-distance thus covering large areas. Their transmissions are easy to pick because they can be picked by cheap radios. In addition, their signals have the capability of reaching remote areas where there is no radio network.

All you need to do is create content and send it to locations with a radio network, where it is beamed and sent back. A shortwave radio can also be accessed through the internet and that is why they are nicknamed to “world band radio”. Shortwave radio is therefore effective in unifying marginalized communities in remote areas.

Longwave radio, on the other hand, has the ability to send signals over a long distance using low power, which makes them suitable for maritime and sea activities.  The normal power level of longwave radio ranges between 500Kw to 2Mw. This means that its power coverage for each kilowatt is far better than that of an MW band transmitter.

5. Power Usage

Radios use the power to transmit signals from one place to the other. Shortwave and longwave radio have contrasting usage of power. While longwave radio requires less amount of power for transmission, the shortwave radio requires a lot of energy.

Longwave radio has a high broadcasting capability which is far much better per each kilowatt, than that of the MW band transmitter. This enables them to cover a large area using low power ranging between 500 Kw to 2 Mw.  Owing to their ability to use less power, they are commonly used for maritime communication where ships need to conserve energy.

Shortwave radio requires huge amounts of power to transmit its signals as they are more susceptible to blockages by buildings and land. In addition, because they don’t bounce in the ionosphere. Although shortwave radio uses much more power than longwave radio, they are more popular across the world than longwave radio due to their characteristics.

6. Sound Quality

The difference in the quality of sound between longwave and shortwave radio is determined by how their signal is encoded. The signal encoding process not only affects the quality of the sound but also its performance and the broadcast range.

Longwave radios vary the broadcast signal that they receive from the transmitter. This, in turn, changes its power since amplitude stands for the signal strength. Owing to the fact that some transmitters are poor at picking out a weak signal, they produce poor sound quality.

Shortwave radio, on the other hand, uses high-frequency range and big bandwidth. Therefore, it does not change the amplitude of its signals enabling them to remain constant throughout the transmission process. Transmitters are therefore able to pick up shortwave radio signals effectively, hence the good sound quality.

Bottom Line:

Owing to the differences that shortwave and longwave radio have, each has its strong point in its own right. Shortwave radio is more popular across the world because it transcends boundaries, water bodies, and mountains in transmitting signals. Longwave radio, on the other hand, performs exceptionally well in the maritime industry, due to its ability to cover a long distance and use less power.

The standout difference between the two types of radio rests on their characteristics like power usage, strength, antenna reception, wavelength and frequency, and their movement tendencies. While the longwave radio is specialized in maritime communication, shortwave radio is excellent in almost every sector such as defense, weather, and broadcasting. However, when everything is said and done, the choice between the two types of radio rests on how you want to use them.

A thermometer is an instrument that is used to measure temperature of the surrounding or the body. The outdoor thermometers reflected here are basically used to detect temperature changes in the environment. Outdoor thermometers are currently helping in various industries and technology as monitoring devices in scientific research, meteorology and medicine. To record accurate information from the thermometer, it must be placed in a strategic location where there is free air circulation.

Factors to Consider While Setting Up an Outdoor Thermometer

Do you have thermometer?

Before deciding where to place the thermometer, it is necessary that you have one. A digital thermometer or a mercury thermometer works best. The thermometer needs to be in good condition so as to give accurate readings after setup. A thermometer can be purchased online or at a local store at a fair cost.


This refers to the space between your house and the strategic position of the outdoor thermometer. The thermometer should be placed further from the building to avoid inaccurate information due to air blockage that occurs. It also recommendable to place it where there is a shade to avoid precipitation caused by direct sunlight. Incase you want the thermometer to be around your house, it must be higher than the roof of your house. Therefore, if your house is 8 feet high the thermometer should be a few feet higher. You should not be place it near the windows since there could be some blockages and the flow of air may not be enough to give the best and accurate results.

How far is the pavement?

Ensure that the thermometer is 40 meters away from the pavement. The reason to this is that pavement contains concrete that has a tendency of absorbing and releasing heat. The contractions in the pavement will automatically interfere with the readings. The reason to this is because the ground has different temperature ranges due moisture and heat from the sun. The conditions on the ground can interfere with the thermometer readings.

Thermometer height

The height should keep off the thermometer from getting in contact with the ground temperature. In case there is some interference, it may interfere with the readings. Therefore, the thermometer must be placed above 5feet from the ground to ensure that temperature on the ground does not come in contact with the sensor. A thermometer placed below the height of a building will always give in accurate readings that cannot be depended upon.

How is the airflow?

A flat area is the best place to put the thermometer since the air is always flowing freely. Sheltered areas such as inside the house or areas near windows are not recommended as the circulation of air is hampered. Hilly areas should be exempted because it can be hard to get flat spaces to position a thermometer. Therefore, you can place your thermometer at an inclined angle. However, readings of a thermometer in such an inclined area may not be accurate as those taken in flat surfaces.

Is it the rainy season?

The rain can destroy a thermometer if it is not properly sheltered.  Maintaining this device is tricky and can become expensive if extra caution is not taken. Mercury enables the thermometer to work and give readings which can be destroyed if rain water gets in contact with it. The best action to take is making a shelter around the thermometer to prevent rain from destroying the device. The shelter should be simple and small in size to avoid inaccurate readings. However, the shelter should be placed only in the rainy season since it can act as a shade when it is sunny.

Away from direct sunlight

The sensor will give higher readings if the thermometer is exposed directly to the sunlight. To get the best readings, ensure there is a shade and there is enough air space at a proper height to avoid blockage. Direct sunlight will make the thermometer give wrong information that may be unhelpful to the user.

Key Features of an Outdoor Thermometer

  • Outdoor sensor that is rechargeable and maintains a full charge for almost one year. It is also durable such that no weather changes can destroy it.
  • It has an indoor temperature that ranges from 3-159 degrees.
  • Temperature tolerance of negative/positive 2 degrees
  • Allow adjustments to be made in advance by trend arrows
  • To ease viewing the changes in temperature, it has a black light display.
  • The thermometer has an outdoor temperature ranging from 59-157 degrees.
  • A transmitter A433MHZ with 198 feet range
  • A humidity range of 9-100%

How Often Should You Calibrate an Outdoor Thermometer?

  • Monthly

To avoid inaccurate readings, it is advisable to calibrate your outdoor thermometer on a monthly basis. This is done especially if you have been making frequent measurements within the month. The critical measurements can interfere with readings in the future if the thermometer is not calibrated regularly.

  • Before a major project

To avoid project risk, it is advisable to follow the instructions given before starting using the readings before a major project.

  • Project requirements

Some projects make it a must to calibrate the device and have them certified. However, failure to follow the instructions can ruin the integrity of the project.

  • Annually

It is calibrated annually if the measurements taken within the year are not critical. It is stated to be the right balance between prudence and cost and for the accuracy of the device it must never go beyond.

  • After a major project

This helps to return the device back to its normal state after testing is completed in a project. It helps to determine the accuracy of the results and find out the margin error of the project.

  • Never

There is no need to calibrate the device if it is only used for gross checks and if you calibrate in such a state the readings will not be accurate. In this case, there must be another thermometer that is regularly used and the spare one that does gross checks.

  • According to the manufacturers’ recommendations

The manual will always direct the user whether to calibrate or not. Manufacturer must have a good reason to state in the manual that the thermometer needs to be calibrated. Instructions provided in the manual have to be followed to the latter to avoid inaccurate measurements

  • After a knock over

This happens after overload of internal protection whereby it is advisable to recalibrate the device and confirm that it is safe. Lack of proper check up of the device will lead to inaccurate readings.

How to Adjust an Outdoor Thermometer

Iced water has to stay for 9-16 minutes to allow the temperature to stabilize. The thermometer has to achieve the lowest degree and to achieve this it has to be put in ice bath. Before adjusting the thermometer to freezing point of water, the current temperature of outdoor thermometer must first be recorded.

Steps followed while adjusting a thermometer

  • Fill a glass with ice cubes and top off with cold water.
  • Mix the water and ice cubes and wait for at least 3 minutes.
  • Mix again and place the thermometer in the glass without letting it touch the glass.
  • Ensure that your hands do not interfere with the glass since it will affect the readings.
  • The temperature should read 0 degrees Centigrade or 32 degrees Fahrenheit.

How do you Know if the Outdoor Thermometer is Accurate

The accuracy of an outdoor thermometer is noted if it registers 0 degrees or 32 degrees Celsius in iced water. To achieve the accuracy, the stem of a thermometer has to be inserted 0.9-inch-deep in the ice water whereby the stem should not be allowed to touch the glass.

Benefits of an Outdoor Thermometer

  • Acts as an external décor

Besides the fact that it gives update on weather, the outdoor thermometer is also a form of beauty to the surrounding. It gives the home a touch of class which is not in many homes. Therefore, during purchase it’s advisable to choose a color and design to match your home.

  • Fast and accurate

An outdoor thermometer will give instant and accurate readings in comparison to listening to radio or watching television on weather forecast. The media will give a forecast for a large region which is not as accurate as an outdoor thermometer. Quick and helpful decisions can be made with an outdoor thermometer. These decisions include prevention from soaking from the rain or catching a cold due to the accurate readings of the outdoor thermometer.

  • Easy to use

An outdoor weather station is easy to use as long as the installation is done perfectly. It is designed in a way that the user will not struggle to operate. The instructions in the manual can be easily understood and followed to the latter. The manual is designed in such a way that anyone with the knowledge of reading can easily understand and also explain to those in need of the information but cannot read.

  • Keeps your home safe

Areas experiencing floods, snow, hurricanes and other destructions caused by changes in weather need an outdoor thermometer. The owner of the home will be able to keep safe before a disaster strikes. However, there will always be solutions after the destruction occurs whereby it will not be severe as it could have happened without prior knowledge.

  • Learning opportunity

Children will be able to learn and understand better on how to use an outdoor thermometer. It becomes easy for them since it’s both practical and real. The children will also be able to understand better weather changes and conditions of their region. The information on how to use, maintain and install an outdoor thermometer can create job opportunities. For instance, your neighbors may learn the benefits of an outdoor thermometer and request your assistance on installation at a fee. Many people will be able to have the outdoor thermometers in their homes hence making it easier for meteorological departments to give better and more accurate weather predictions. The signals from the outdoor thermometers owned by people can be transmitted to meteorological centers and enhance the accuracy of the weather reports.

  • Portable

This thermometer can fit in a handbag and is very light compared to the great work it does. Therefore, after purchasing it is possible that all other errands can be done without getting tired. However, after installation it will become a close friend since every now and then it will be always available to calm your curiosity concerning weather changes.

  • Ideal for farmers

Homeowners who enjoy farming should invest in an outdoor thermometer that will help them know when to plant, harvest, dry grains and avoid destructions of crop caused by the harsh weather conditions. It will also aid in securing your animals when the weather becomes extreme.

  • Real time alert

Weather is unpredictable and therefore the outdoor thermometer will help family members keep safe from harsh condition like floods and hurricanes without prediction from the meteorology departments. An outdoor thermometer gives the most accurate prediction as it focuses only on the exact surroundings. There is no need to watch television or read newspaper so that you can know about news forecast. In comparison to the news forecast, the outdoor thermometer will give you weather forecast of your specific area. Television forecast give general information which is not as vital as the one from outdoor thermometer.

  • Acts as a clock

This is advantageous to the user since in addition to the thermometer, there is a clock to keep time. No time is misused as the clock is within your environment and readings are accurate. An alarm can be set to alert the user when to perform daily chores without wasting much time. Time is precious and with the presence of a clock, no planned duty will be skipped at the end of the day.


An outdoor thermometer is one of the best devices your home should never lack. It benefits both parents and children as it can be easily installed because the instructions are simple from the manual. The owner of the thermometer feels safe even in the event that there are drastic weather changes. Weather disasters like snow, floods and hurricanes will always meet you prepared and hence no damages are likely to get severe. Investing in an outdoor thermometer is not a waste of finances since it works as a form of security to the entire environment in relation to weather changes.

Unlike the standard contact thermometers, infrared thermometers measures reflected light by objects at specified wavelengths. They are used in a wide range of environments and industries to measure surface temperatures quickly. Their efficiency in efficiently detecting potential errors in electrical circuits, building systems, and mechanical equipment, helps avert catastrophes.

Making precise and accurate temperature measurements play a key role in the success of many businesses like manufacturing. This underlines the importance of checking the accuracy of your infrared thermometer. The best way to go about this is by checking the accuracy of the thermometer to make sure you get the right temperature measurements.

This article will outline everything you need to know on how to check the accuracy of your infrared thermometer, and the factors that affect its accuracy.

Accuracy of Infrared Thermometer

Accuracy of Infrared Thermometer

1. Use a Blackbody Calibrator

Theoretically, blackbody calibrators are “perfect emitters,” which means that they emit maximum infrared energy at a given temperature. Besides, they radiate the same radiation intensity in every direction. That is the reason why they provide a strong calibration basis when checking the accuracy of infrared thermometers.

With the use of an accurate pyrometer, the blackbody temperature is measured, and because its emissivity is known, it offers accurate calibration. The majority of manufacturers use this method to calibrate their pyrometers and IR thermometers. However, the downside with this accuracy checking method is that blackbody calibrators are expensive and a reserve of the big companies.

2. Use Accurate Pyrometers

Accurate pyrometers record accurate temperature measurements of an area or object. To check the accuracy of your thermometer, you first need to measure and record the temperature of an area or object using an accurate pyrometer.  You then measure the exact area using your infrared thermometer and compare measurements. If you find that the two measurements are not corresponding, that means your thermometer is not accurate and will need to be calibrated to match the accurate pyrometer.

When using this method, you must ensure that the pyrometer you are using is accurate; if you have doubts about its accuracy, using two pyrometers can help. Besides, you should measure the temperature of the exact area with the exact thermal energy to ensure accuracy. Different areas or objects will most likely than not record different temperature measurements.

3. Use Thermocouple

A thermocouple is an instrument consisting of different metal wires that are welded at a junction. Changes in temperature make the junction to create a voltage, after which thermocouple tables are used to calculate temperature measurements and interpret voltage.

In this case, an object’s temperature is measured using the accurate thermocouple and recorded, after which the thermometer is used to measure the same object. Their measurements are then compared, and if they do not match, the thermometer is calibrated to rhyme with that of the thermocouple. When using this method of accuracy check, you must measure the same area of the object to ensure accuracy.

It is important to note that thermocouples are not 100% accurate as they wear and tear quite often. However, they come in different varieties, and most often than not, the costly ones tend to have high accuracy. You need to first confirm the accuracy of the thermocouple before using it to base your measurements for accuracy purposes.

4. Ice Water Test

If you do not have a thermocouple, pyrometer, or blackbody calibrator, you can use the ice water test. You have to fill your glass with ice and fill it with water to fill the ice gaps. Let the glass settle for some time preferably two minutes, after which you stir its contents until they are uniform.

Hold your IR thermometer directly on top of the glass at about 3 inches and ensure the thermometer lens is placed at 90 degrees above the glass. Ensure that the thermometer lens is solely aimed at the ice and water to avoid a view of the walls of the grass of the background, which will affect the measurements. If your IR thermometer is reliable and accurate, and you correctly follow these steps, it should record 32.0 degrees.

5. Use Infrared Comparator Cup

The infrared comparator cup allows for a comparison of its accuracy and that of the IR thermometer without using ice and water temperatures. The aluminum cup is made of matte black solid coating and a stable flat surface. Its walls help to shield air currents found in the room from its surface which could affect the accuracy test, while the mass at its base is meant to provide temperature stability.

The reference thermometer is inserted in the cup and allowed to settle for a few minutes for stability. The infrared thermometer is then pointed at the object inside the infrared comparator cup with the same care outlined in the ice water test. If the IR thermometer is accurate, its readings must match with reference thermometer’s readings.

6. Use a Surface Probe

Another instrument that you can use to check the accuracy of your IR thermometer is the surface probe. Just take and record the surface temperature measurements of the testing object using an accurate surface probe. When taking these measurements, you must ensure that the environment temperature around the objects is stable.

After you have made sure that your IR thermometer readings are stable and you have recorded them, point it to the object from a few centimeters away. Ensure that you point it at the exact spot that you pointed your surface probe and record the readings. If the two readings don’t match, your thermometer is not accurate, and you will need to adjust its emissivity.

Instructions to follow when conducting IR thermometer accuracy test

Infrared thermometer accuracy tests require one to have a stable surface whose temperatures are known and follow instructions. Outlined below are some of the simple instructions that will help you crack the accuracy test.

  • The IR thermometer must be allowed to settle for a few minutes in the room where the tests are being done. This is meant to allow the thermometer to adjust to the room temperatures and thus increase its accuracy. For instance, in case you have removed it from a chiller, you must give it time to settle for about 15 – 20 minutes before conducting any tests.
  • Ensure your IR thermometer’s lenses are clean before conducting any accuracy tests. In case it has grime, condensation, or debris, it might give misleading measurements. However, you must trend carefully when cleaning it to avoid scratching it or damaging the sensor. The best way of cleaning your thermometer’s lens is by using soft cotton dipped in alcohol.

Clean the lens first and then the body later to avoid causing any damage to them. After cleaning the lens, allow it to dry before use and avoid submerging any of the thermometer’s parts in the water when cleaning, as it can cause damage.

● Avoid conducting accuracy

  • If conducting the IR thermometer accuracy tests using other instruments like thermocouples, pyrometers, blackbody calibrators, or infrared comparator cup, among others, you must confirm their accuracy first. It would not make any sense basing your accuracy tests on faulty instruments, which will only give you wrong measurements.
  • Consider your thermometer’s field of view, which is the distance to target ratio, because it affects its readings. If you falter on the field of view of your thermometer, it will pick up the background of the object and thus give misleading measurements. Each thermometer has its distance to the target ratio indicated on them or in their manual which means all you need to do is obey them.
  • Avoid conducting accuracy tests in dusty and steamy rooms. Dust and steam affect the normal functioning of IR thermometers thus recording faulty measurements. If the room is dusty and steamy, you can change the venue and conduct the test in a conducive room.
  • Set your thermometer’s settings at 0.95 to 0.97 before conducting any accuracy test. Setting the emissivity of your thermometer enables it to give you the correct readings. Some of them come with factory-set emissivity settings, which are fixed. Emissivity is the measure of an object’s ability to emit infrared energy.

Determinants of Your IR Thermometer Accuracy

Your IR thermometer’s accuracy is determined by a host of factors that you should not overlook while conducting any test. These factors ensure that you get the accurate measurements that you need, as outlined below.

  • Distance to target Ratio

The distance to the target ratio put is the size of the target area being measured by the thermometer with its distance. This ratio plays a key role in determining the accuracy of the temperature measurements. If the distance to the target ratio of your thermometer is 12:1, this means that when the thermometer is 12 cm away from the object, its diameter is 1cm.

Therefore, if you increase the distance to 13cm, the thermometer will record the temperature of the object plus its background, thus giving false distorting measurements. Distance to the target ratio is displayed on the thermometer, and it’s manual. You must obey your thermometer’s distance to the target ratio for accurate temperature measurements.

  • Field of view

IR thermometer uses a laser to record the energy emitted by objects, which determines the surface temperature of an object. Therefore, laser guides you on the area to test as it is aimed below the testing area. Most of the thermometers available like IRFS, IR-Gun, IRK, or IRT have their lasers located below their lens.

To get accurate measurements, you must aim the lasers directly to the test area at an angle of 90 degrees. A simple mistake in the position of the laser will give you the wrong measurements. Weed through your thermometer to find the location of your laser so that you can correctly position your field of view.

  • Emissivity settings

Every IR thermometer has emissivity settings responsible for recording the maximum amount of energy that objects emit. Some are manufactured with fixed factory set settings, while others have adjustable emissivity settings. For optimum performance, the ideal emissivity settings of an accurate IR thermometer should be 0.95 up to 0.97.

Objects with high or low emissivity levels either reflect or absorb infrared energy, thus affecting the temperature measurements. When measuring the temperature of shiny objects, you must adjust the emissivity settings on your thermometer to record accurate measurements. Besides, you could rap them with non-reflective tape or apply flat paint to record perfect measurements.

  • Obscured optics

The location that you carry out measurements using the infrared thermometer can affect accuracy. For instance, carrying out measurements in steamy or dusty surroundings deflects infrared energy emitted by objects before they can reach the thermometer laser and lens, thus recording faulty measurements.

Also, a dirty or fogged lens could impair the ability of the thermometer to record the energy needed to make measurements. This is the reason why you are discouraged against using the dirty lens and taking measurements in locations filled with dust and steam.

  • Temperature shock

Whenever an IR thermometer is transferred to surroundings with different temperatures, they suffer temperature shock. This, in turn, forces them to record faulty measurements. That is the reason why it is important to allow your thermometer to settle for about 15 to 20 minutes after taking it to warmer or colder surroundings. This allows them to acclimatize with the surroundings thus increasing their accuracy.

Bottom Line

Infrared thermometers offer an excellent combination of convenience, speed, and accuracy. Whether you want to measure the temperature of electrical systems, grill surfaces, and duct, among others. They are, therefore, the perfect replacement to standard thermometers, which cannot simply do the work. However, the secret to using them effectively lies in using them correctly by following the laid down instructions as outlined above.

Besides, it is important to ensure that they are giving accurate measurements so that you can make informed decisions. You can only achieve this by carrying out accuracy tests and following their manual instructions. If you follow the accuracy tests above, they will help you to increase the accuracy of your measurements.

You might not have thought it necessary to convert temperature from one unit to the other just because tons of digital instruments can do this anyway. With digital thermometers and your smart devices, you didn’t need to bother yourself with the mundane task of converting Degrees Celsius to Degrees Fahrenheit.

For those living in countries that have adopted the Metric System decades ago, it seems hardly necessary to make any conversion.  It is simple enough to continue recording all temperatures as Degrees Celsius without any thought of what it means in Degrees Fahrenheit.

It has not always been like that:

Degrees Fahrenheit

Before Degrees Celsius was widely used, the primary temperature unit was Degrees Fahrenheit. Denoted with the symbol °F, this unit of measuring temperature is defined as two fixed points: the freezing temperature of water at 32°F, and the temperature at which water boils at 212°F. These temperatures are measured at sea level and with the standard atmospheric pressure. The space between these two points is split into 180 equal parts.

Way back in 1724, a German physicist by the name of Daniel Gabriel Fahrenheit developed the unit of measuring temperature named after him. To arrive at his definition for hot and cold temperatures, he at first used a scale that featured an equal amount of ice-salt mixture. He selected 30°F as the point where water freezes and 90°F as the average temperature of the human body. Later he tweaked the scale to show 32°F as the point where snow melts and 96°F as the normal temperature of the human body.

As the reference to water’s boiling and freezing points became more widely accepted he again adjusted his scale to enable 180 degrees to separate the boiling and the freezing points on the thermometer. This adjustment meant that 98°F and not 96°F was accepted as the normal human body temperature.

Currently, most countries no longer use Degrees Fahrenheit as the official unit of measuring temperatures.  Only a few countries, including the United States of America which did not adopt the Metric System, still use Degrees Fahrenheit to measure temperature.

Degrees Celsius

Degrees Celsius, on the other hand, which is denoted by the symbol °C is a derived unit of measuring temperature within the International System of Units.  It is based on the absolute zero (that is -273.15 °C), and the three-part water standard termed the Vienna Standard Mean Ocean Water (VSMOW). The Celsius scale (also equated with the Kelvin scale) was adopted from 1743 until 1954.  During that period the points 0 °C to denote water’s freezing point and 100 °C to show its boiling point were used. These points were measured at one standard atmospheric pressure with mercury as the thermometer’s material. (Initially 0°C was used to show water’s boiling point and 100°C as the point where snow melts).

With the redefinition of Degrees Celsius in 1954 (the first definitions of boiling and freezing points were flipped on their heads) measuring temperature in Degrees Celsius became more widely accepted. It was also still based on the absolute zero (-273.15 °C) measure.

Now that we have an idea of the origins and history of both units of temperature measurement let’s dive straight into how to convert from Celsius to Fahrenheit.

Converting from Celsius to Fahrenheit

Celsius to Fahrenheit table

For those of us who are not good with numbers, this section might be a little daunting. Here is the breakdown of the formula that must be used to achieve the conversion:

The formula: F = 9/5C + 32.

Looks simple enough.  Another way of stating this formula is to write it out as F = (9/5 x C) + 32.

“F” represents Fahrenheit (the unit you want to convert to), and “C” represents Celsius (the unit you want to convert from).


But, what is 9/5?


The above is the fraction you must use to multiply the value of the temperature in Degrees Celsius. You might say this is the factor needed to start the conversion process. Another way to express this fraction in decimals is 1.8 (which is merely the result of nine divided by five which is less than two times.)

So, you might see this temperature conversion formula presented in other texts as F = 1.8 C + 32. Rest assured, it means the same thing.

Finally, add the number 32 to the results of your previous multiplication effort.

But, why would you need to add this number?

It so happens that 32 °F represents the same temperature as 0°C. It is, therefore, necessary to account for this whenever you convert from Celsius to Fahrenheit.

To recap:

Converting from Degrees Celsius to Degrees Fahrenheit needs two steps.

Step one – multiply the Celsius temp by 1.8 (the same thing as 9/5 remember)

Step two – add the result to 32.

Here is an example of this:

Converting 25 °C to °F:
25 °C = 25 × 1.8 + 32 = 77 °F

With a further show of working, it would go like this:

25 °C = 25 × 1.8 = 45

45 + 32 = 77 °F

So, from the example above, 25 °C is equal to 77 °F.

You can have fun using this simple formula to convert any temperature expressed in Degrees Celsius into Degrees Fahrenheit.  Of course, if you want to switch back to Degrees Celsius, the formula can be used with one significant difference – rather than adding 32 to the result, you would need to subtract it instead.

Converting without a calculator

What if you don’t need to do an exact conversion and all you need is a rough estimate? This situation may be quite relevant if you do a lot of cooking and need only to do quick conversions without bursting your brain cells and using a calculator.

Here is an alternative approach in this case:

To convert from Celsius to Fahrenheit multiply the Celsius temperature by 2.  Add 30 to the result.

With this rough method, you can easily convert 25 °C to °F.

Here goes:

25 x 2 = 50

50 + 30 = 80

So, by the above working, the rough estimate provided by your quick (mental) conversion is that 25 °C  is roughly around 80°F.  Not too far off from the more accurate calculation of  77°F we worked out earlier.

Things to Remember

Are you comfortable doing temperature conversions on your own? Once you know the formula to use, it becomes a no-brainer.  You can efficiently practice using it to good effect and even impress your friends and associates on your mathematical prowess.

  • It is important to remember that you need to take the two steps required to make the conversion. Multiply then add. If you try to do it the other way around (add then multiply) you will only succeed in messing things up.
  • Also, ensure that you are converting from Celsius to Fahrenheit. So, the thermometer should first give you a reading in Degrees Celsius.  The temperature is what you would then need to convert.
  • Also, you must use the multiplier (9/5 or 1.8 which both means the same thing).  No other figure will do the job. If you forget to multiply the temperature by this fraction (decimal), you won’t get a correct answer even if you remembered to add the number 32 to that amount.  In fact, such a result will always be lower than the right answer!
  • Of course, also remember to add the number 32 to the result you get. This figure is the number you must add and no other value.  As mentioned earlier, this number in Fahrenheit represents the temperature of water at zero degrees Celsius.
  • If you are in a pinch and need a quick, easy to remember formula to give you a rough estimate, you have it in the formula steps “multiply by two then add 30”. This approach provides a quick solution in the event you are cooking and need a rapid temperature check in Fahrenheit instead of Degrees Celsius.

Final Conclusion

There might be times when you need to convert temperature from Degrees Celsius to Degrees Fahrenheit quickly.  While it is possible to use digital thermometers and smart devices to accomplish this, you might not always have these convenient tools around. If you must do so without help from digital instruments, a simple mathematical formula comes to the rescue.

It is not a complicated formula to remember, and it involves two easy steps to convert any Celsius temperature to temp in Fahrenheit. In a pinch, you can also use a simple formula to arrive at a rough estimate of the temperature conversion without much cranial stress.

Most of all, it is easy and fun to do this simple temperature conversion on your own.

Of course, if you don’t care too much about working this conversion yourself, you can take comfort in your knowledge of how to do it. You also won’t have trouble understanding what is involved whenever you come across examples of temperatures that were converted from Celsius to Fahrenheit.

The extent of hotness or coldness of an object or a body is referred to as Temperature. In scientific terms, it is the measure of the mean kinetic energy of the inordinate motions of the particles present in a certain system. The importance of temperature in our daily lives cannot be overemphasized; it is vital in our everyday lives and in several fields such as medicine, natural sciences, among others.

We appreciate the temperature of a place or body with the use of a thermometer. They are calibrated in one or more temperature scales. Around the globe, there are three prominent temperature scales; Celsius scale (previously referred to as centigrade, denoted as °C), Kelvin scale (denoted as K) and Fahrenheit scale (denoted °F). However, the International System of Units (SI) which has 7 fundamental quantities, among which is temperature utilizes the Kelvin scale (k). This scale is extensively utilized in sciences and technology.

Background of Temperature Scales

Even though there are several temperature scales, the most common ones are the Fahrenheit, Celsius and Kelvin. Temperature values can be converted from one temperature scale to another using formula and other methods. However, you must first of all understand how the scales were invented and what they measure so you can easily convert from one scale to another.

The Fahrenheit scale was invented by Daniel Gabriel Fahrenheit, a physicist from Germany in 1724. Following his invention of the mercury thermometer in 1714, he wanted to be able to measure temperature accurately. With this scale, the freezing and boiling points of water are divided into 180 degrees, taking 32 F as the freezing point of water while 212 F is assumed as the boiling point. The design of the Fahrenheit thermometer was based on that original temperature and pressure device described by Galileo. Today, the Fahrenheit scale is used primarily in the United States of America.

The Celsius temperature scale, which is oftentimes called the centigrade scale, was devised by Swedish Astronomer Anders Celsius in 1741. The word centigrade literally refers to “consisting of or divided into 100 degrees”: meaning that the Celsius scale consists of “100 degrees between the freezing point of 0 degrees and boiling point of 100 degrees of pure water at sea level air pressure, 29.92 inches of mercury”. In 1948, the International symposium on weights and measures adopted the term Celsius and it has become one of the most extensively used scales in the world.

There is a third temperature scale that is utilized by Scientists for unique measurements. This scale is referred to as the absolute or Kelvin scale. It was devised by a British Scientist, William Thomson, also referred to as Lord Kelvin. He made significant discoveries about heat and its properties in the 19th century. According to scientists, it is only possible theoretically for a body to get as cold as minus 273.15 degrees Celsius. Even though this temperature has not been reached in experiments, scientists have come close. Hence, the number, minus 273.15 degrees Celsius, is referred to as the absolute zero. Scientists are of the view that molecular motion is no longer possible at this temperature, hence it is impossible to get colder than that.

While the Fahrenheit scale is mostly used in the United States, the Celsius is popular in most other Western nations, but is also used in the United States. Even though you can convert temperature values from one temperature scale to another using different online converter, it is advisable to understand how to convert one scale to the other in other to obtain accurate temperature readings.

There is another temperature scale that is utilized in specific calculations and measurements but is now obsolete. Devised by a French scientist named R A F de Raumur (1683-1757), the Raumur scale was extensively utilized in France and by scientists to make temperature measurements in the 18th and 19th centuries before the advent of the Fahrenheit and Celsius scales. Raumar did not utilize mercury in his work but came up with a good working thermometer. He used the freezing point of water as his zero mark, and put the boiling point at 80 degrees.

Another lesser known scale is the Rankine scale, developed by W J M Rankine (1820-1872), a Scottish engineer. However, the scale was just a Kelvin scale utilizing the Fahrenheit degree rather than the Celsius. Even though it was widely used in certain scientific communities, it does not have any practical use in other areas of measurement.

For the purpose of this article, we will look at the three most popular temperature scales: Fahrenheit, Celsius and Kelvin.

Temperature Conversion Formulas

The table below shows how to convert temperature values from Celsius to Fahrenheit, Kelvin to Fahrenheit, Fahrenheit to Celsius, Celsius to Kelvin, Kelvin to Celsius and Fahrenheit to Kelvin.

Celsius to Fahrenheit ° F = 9/5 ( ° C) + 32
Kelvin to Fahrenheit ° F = 9/5 (K – 273) + 32
Fahrenheit to Celsius ° C = 5/9 (° F – 32)
Celsius to Kelvin K = ° C + 273
Kelvin to Celsius ° C = K – 273
Fahrenheit to Kelvin K = 5/9 (° F – 32) + 273

From the table, if you know the temperature in Fahrenheit and want to convert it to Celsius, you will use the formula:

C = 5/9 x (F-32); where C is Celsius

This entails first subtracting 32 from the temperature in Fahrenheit and multiplying the outcome by 5/9. The formula is:

To make this clearer, we will use an example.

Let’s say you want to convert 70 F to Celsius. Follow these steps:

  1. 70 minus 32 is 38
  2. 5 divided by 9 is 0.5555555555555
  3.  Multiply the result by 38
  4. The answer is 21

If you use the equation,

C = 5/9 x (F-32)

C = 5/9 x (70-32)

C = 5/9 x 38

C = 0.55 x 38

C = 20.9, which rounds to 21

Therefore, 70 F is equal to 210C.

You can check your work by converting 21 degrees Celsius to Fahrenheit to check your work, as follows:

  1. 9 divided by 5 is 1.8
  2. 1.8 multiplied by 21 is 37.8
  3. 37.8 plus 32 = 69.8
  4. This is rounded off to 70F

To convert from Celsius to Fahrenheit, using the same values, use the formula below:

F = [(9/5)C] + 32

F = [(9/5) x 21] + 32

F = [1.8 x 21] + 32

F = 37.8 + 32

F = 69.8, rounded off to 70F

It is also possible to convert from Celsius to Fahrenheit by using a fast approximation method. Here, you will double the temperature in Celsius, subtract 10 percent of your result and add 32.

Let’s say for example that the temperature of a European city is 19C. If you need to convert that to Fahrenheit so you will know exactly how to dress outdoors, you can do a quick conversion. First, double the 19, or 2 x 19 = 38. Then, calculate 10 % of 38 to yield 3.8, rounding it up to 4. Next, calculate: 38 – 4 = 34 and then add 34 and 32 to get 66 F. This means that all you need for going outdoors is a sweater but not a big coat.

Using another example, say the temperature of your destination is 28 C, you can then calculate the approximate temperature in Fahrenheit by following the steps below:

  1. Double 28 doubled = 56 (or 2 x 28 = 56) 
  2. 10 percent of 56 = 5.6, which rounds to 6
  3. 56 – 6 = 50
  4. 50 + 32 = 82

You can also use the scale to convert from Celsius to Kelvin. Firstly, it should be noted that the Kelvin scale uses this number as zero. Therefore, to obtain temperature vales in Kelvin, you have to add 273 degrees to the Celsius temperature.

Type the temperature value to be converted in the °F, °C, or °K box and click the submit button

Fahrenheit: Celsius:   Kelvin:

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So, you want to learn how to convert temperature from one temperature scale to another. Apart from going online to use any of the handy temperature conversion tables or formula, you can do it yourself the old school way. With a simple formula or two, you can easily convert temperatures as much as you like.

But, before we get into the nitty-gritty of converting temperature, here are a few things you might want to know.

What we know as the temperature is the amount of energy that matter uses to move its particles. As particles move around, the temperature changes. The more movement there is, the higher the temperature and by contrast, the less movement, the lower the temperature. That is why things get hotter when there is more movement (a simple act of rubbing your hands together (to create friction) also results in a little heat (temperature).

Also, five different scales have been developed to measure how hot or cold things are. These scales are Fahrenheit, Celsius, Kelvin, Rankine, and Réaumur.

We are acquainted with the first two scales since they are used for everyday temperature measurement. The other scales are less popular and are used mainly in scientific circles.

Let’s Take a Closer Look at Each Scale:

Fahrenheit Scale

The Fahrenheit scale was named after Dr. Daniel Gabriel Fahrenheit, a German physicist in 1714. In this scale, negative temperatures (below zero) are included, and the coldest possible temperature on this scale is – 459.67 degrees. The Fahrenheit temperature scale is still used in the United States, while other countries have adopted the metric system which includes the Celsius scale.

Celsius Scale

Did you know that degrees Celsius was initially known as degrees Centigrade? The Celsius temperature scale was later renamed after Dr. Anders Celsius, a Swedish astronomer who had developed it in 1744. The name Celsius was adapted in 1948. Every country other than the United States uses degrees Celsius as the official scale for measuring temperature. This scale sets the freezing point of water at 0 degrees and the boiling point at 100 degrees. Negative temperatures below zero are also included, and the coldest possible temperature (absolute zero) is – 273.15 degrees Celsius.

Kelvin scale

In 1848 a British scientist, William Thomson (who later became the 1st Baron of Kelvin) developed the Kelvin scale. This scale, which was an adaptation of the existing Celsius scale, is based on the principles of thermodynamics. Not only was the Kelvin scale an alternative to the Fahrenheit and Celsius scales, but it was also to become the preferred scale for scientific measurement and calculations for temperature. One of the main changes introduced by the Kelvin scale was to establish a value for the absolute zero temperature, which is the coldest possible temperature that can be measured. This value was set as zero K (Kelvin does not use degrees in its notation since 1967). Within the Kelvin, scale water freezes at 273.15K, and the boiling point is 373.15K.

Rankine scale

In 1859, shortly after the Kelvin scale was created, William John Rankine, a Scottish scientist, developed the Rankine scale. It provided an absolute zero value equivalent to what was on the Fahrenheit scale. Like the Kelvin scale, the Rankine scale is also based on the thermodynamic measurement of temperature. In this scale, water freezes at 491.67 °R and reaches its boiling point at 671.67°R. The Rankine scale is not used widely but only in the United States within specific fields of engineering.

Réaumur scale

Even before the establishment of the Celsius, Kelvin, and Rankine scales, the French developed the Réaumur scale. Named after the French scientist René Antoine Ferchault de Réaumur, this scale established the freezing and boiling points of water at 0 °Re and 80 °Re respectively. The Réaumur scale which at first was widely used in France, Russia and Germany, fell out of widespread usage and was finally restricted to measuring milk temperature in Swiss and Italian cheese factories, and measuring sugar temperature during the making of syrup in the Netherlands.

Temperature Conversion Table

C=5/9 (F-32)        F=(9/5C) +32

°C °F °C °F °C °F °C °F °C °F °C °F °C °F
-40 -40 -10 14 20 68 50 122 80 176 110 230 140 284
-39 -38.2 -9 15.8 21 69.8 51 123.8 81 177.8 111 231.8 141 285.8
-38 -36.4 -8 17.6 22 71.6 52 125.6 82 179.6 112 233.6 142 287.6
-37 -34.6 -7 19.4 23 73.4 53 127.4 83 181.4 113 235.4 143 289.4
-36 -32.8 -6 21.2 24 75.2 54 129.2 84 183.2 114 237.2 144 291.2
-35 -31 -5 23 25 77 55 131 85 185 115 239 145 293
-34 29.2 -4 24.8 26 78.8 56 132.8 86 186.8 116 240.8 146 294.8
-33 -27.4 -3 26.6 27 80.6 57 134.6 87 188.6 117 242.6 147 296.6
-32 -25.6 -2 28.4 28 82.4 58 136.4 88 190.4 118 244.4 148 298.4
-31 -23.8 -1 30.2 29 84.2 59 138.2 89 192.2 119 246.2 149 300.2
-30 -22 0 32 30 86 60 140 90 194 120 248 150 302
-29 -20.2 1 33.8 31 87.8 61 141.8 91 195.8 121 249.8 151 303.8
-28 -18.4 2 35.6 32 89.6 62 143.6 92 197.6 122 251.6 152 305.6
-27 -16.6 3 37.4 33 91.4 63 145.4 93 199.4 123 253.4 153 307.4
-26 -14.8 4 39.2 34 93.2 64 147.2 94 201.2 124 255.2 154 309.2
-25 -13 5 41 35 95 65 149 95 203 125 257 155 311
-24 -11.2 6 42.8 36 96.8 66 150.8 96 204.8 126 258.8 156 312.8
-23 -9.4 7 44.6 37 98.6 67 152.6 97 206.6 127 260.6 157 314.6
-22 -7.6 8 46.4 38 100.4 68 154.4 98 208.4 128 262.4 158 316.4
-21 -5.8 9 48.2 39 102.2 69 156.2 99 210.2 129 264.2 159 318.2
-20 -4 10 50 40 104 70 158 100 212 130 266 160 320
-19 -2.2 11 51.8 41 105.8 71 159.8 101 213.8 131 267.8 161 321.8
-18 -0.4 12 53.6 42 107.6 72 161.6 102 215.6 132 269.6 162 323.6
-17 1.4 13 55.4 43 109.4 73 163.4 103 217.4 133 271.4 163 325.4
-16 3.2 14 57.2 44 111.2 74 165.2 104 219.2 134 273.2 164 327.2
-15 5 15 59 45 113 75 167 105 221 135 275 165 329
-14 6.8 16 60.8 46 114.8 76 168.8 106 222.8 136 276.8 166 330.8
-13 8.6 17 62.6 47 116.6 77 170.6 107 224.6 137 278.6 167 332.6
-12 10.4 18 64.4 48 118.4 78 172.4 108 226.4 138 280.4 168 334.4
-11 12.2 19 66.2 49 120.2 79 174.2 109 228.2 139 282.2 169 336.2

Example: 80 degrees C = 176 degrees F & 14 degrees F = -10 degrees C

How to Convert Temperature

Now that you know the various scales used for measuring temperature, let’s learn more about how to convert values from one scale to another. You must use numbers and equations. Of course, there are numerous online applications for doing the different temperature conversions easily.

But, for those who love the challenge of working things out for themselves, here are a few points to note when converting temperature between scales.

1. Learn The Freezing and Boiling Points of Water.

Every temperature scale has established the freezing and boiling points of water. Before you can do a temperature conversion, you would need to have an idea of what these are. So, for example, the Fahrenheit scale shows the freezing point of water as 32°F and the boiling point as 212°F. On the other hand, the point at which water freezes on a Celsius scale is 0°C while the boiling point is 100°C.

If you continue with the other scales, you will see that the freezing and boiling points are as follows:

• Kelvin: Freezing 273.15K, Boiling 373.15K
• Rankine: Freezing 491.67°R, Boiling 671.67 °R
• Réaumur: Freezing 0 °Re, Boiling 80 °Re

With the knowledge of the freezing and boiling points, you will also get an idea of the intervals between these points on each scale. So, for example, the Fahrenheit scale has 180 points between the freezing and boiling points, and the Celsius scale has 100 points. The intervals for the Kelvin scale is, therefore, 100 (just like the Celsius scale), for the Rankine scale 180 (just like the Fahrenheit scale). Only the Réaumur has a lower interval of 80 points between freezing and boiling points.

2. Understand The Formula

To successfully convert temperature values from one scale to another, you must understand the formula used in each case. Doing so is essential to arrive at the right values and avoid errors that spoil whatever you are doing. Whatever you do to convert from one scale to the next, you must do the exact opposite to reverse the conversion. In the following sections of this article, you will learn how to apply each formula to do the conversions.

3. Have Fun

Having fun with temperature conversions may be the last thing you had in mind, but this can help you get over the challenges of numbers and formulae. Once you get the hang of each method, it becomes quite easy to do each conversion. It is fun too. Did you know the temperature of dry ice in Fahrenheit, Celsius, and Kelvin? What about liquid air? Absolute Zero? Here are the answers:
• Dry ice (solid CO₂) is -108 degrees Fahrenheit or -78 degrees Celsius, -200 K.
• Liquid air is -312 degrees Fahrenheit or -191 degrees Celsius, -100K,
• Absolute zero (the coldest possible measurable temperature) is -459 degrees Fahrenheit or -273 degrees Celsius, -0K.

Different Types of Temperature Conversation

Let’s talk about the different types of temperature conversion. To understand them, consider the five scales used to measure temperature. As you have learned, these are the popular Fahrenheit and Celsius, and the less widely used scales – Kelvin, Rankine, and Réaumur.

Each scale is, of course, different. The main difference among these scales is the freezing and boiling points of water as you have seen earlier.

Of course, with five different temperature scales to work with, there are multiple ways to convert temperature from one scale to the next. So, you have conversion from Fahrenheit to Celsius, Fahrenheit to Kelvin, Fahrenheit to Rankine, and Fahrenheit to Réaumur. You can also convert them back to Fahrenheit. The same principle applies when for converting Celsius to Fahrenheit, Kelvin, Rankine, and Réaumur.

You get the idea:

Converting from Kelvin to the other scales and back again is entirely possible. Converting from Rankine to the other scales, as well as converting from Réaumur to the different scales is also possible. To do so, you would need to use the relevant formula and equations.

Let’s look at these formulae and equations in the next sections.

Temperature Conversion Formula

To convert from degrees Fahrenheit to degrees Celsius, take 32 from the Fahrenheit temperature then multiply by .5556 (or 100/180 simplified as 5/9). Stated another way, deduct 32, multiply by 5, finally, divide by 9.

That’s it! Easy peasy.

Here is an example of how this formula works:

40°F – 32 x .5556 = 4.5°C

Put another way, here is the example again.

40°F – 32 = 8
8 x .5556 = 4.5°C

Was that clear? Would you be able to convert Degrees Fahrenheit to Degrees Celsius on your own?
Using the fractions in your calculation, here is an example to convert Fahrenheit to Celsius:

First: 90° − 32 = 58
Then: (58 × 5) / 9 = 290/ 9 = 32.2° C

Let’s now look at converting degrees Celsius to degrees Fahrenheit.
What do you think we need to do in this case? Do the reverse of what was done to convert °F to °C. Multiply the degrees Celsius by 1.8 (or 180/100 simplified as 9/5) then add 32. Expressed another way, multiply by 9, divide by 5, finally add 32.

That’s all. There is nothing to it.

Here is an example: 50°C x 1.8 + 32 = 122°F

Or, shown as two steps:

50°C x 1.8 = 90
90 + 32 = 122°F

Got it?

Using the fractions in your calculations here is an example to convert Celsius to Fahrenheit:

First: (30° × 9) / 5 = 270/5 = 54
Then: 54 + 32 = 86° F

You have seen the formula most commonly used to convert Fahrenheit to Celsius and vice versa. There are, however, other formulae that you can apply to get the same or similar results when converting between Fahrenheit and Celsius.

The first one is to add 40, then multiply the values, followed by subtracting 40. The reason for using 40 in this calculation is that this is where both Fahrenheit and Celsius are equal. That is −40° C is equal to −40° F.

So, to convert Fahrenheit to Celsius using 40 in the calculations, first add 40 to the Fahrenheit value (for example 40 degrees) The sum is 80. Next, multiply by 5/9 or .5556 to get 44.45. Finally, subtract 40 to get 4.45. As you can see from the earlier example using the previous conversion formula, this result is very close.

To convert Celsius to Fahrenheit using 40 in your calculation will be just as easy. In this example, you are turning 50 degrees Celsius to Fahrenheit (as you have done in the previous case using the other formula).

First, add 40 to 50 to get 90. Then multiply 90 by 9/5 or 1.8 to reach 162. Finally, subtract 40 to reach 122°F. Again, as you can see, the result in this example is the same as the one arrived at when you used the formula 50°C x 1.8 + 32.

You can use other formulas to estimate temperatures quickly. So, to convert from °C to °F, multiply the value by 2, then add 30. For °F to °C conversion, subtract 30 then divide by 2. Remember that the results you get when you use this approach will not be the same as your results using the other equations. This formula is handy when you want to get a quick temperature conversion (such as when cooking).

Here are the formulae you will need for conversions to and from Kelvin, Rankine, and Réaumur.

Conversion to Kelvin

• From Fahrenheit: Subtract 32 from the temperature in Fahrenheit, multiply by 5, then divide by 9 (alternately, multiply by .5556), finally subtract 273.15.
• From Celsius: Add 273.15 to the temperature in Celsius to get the temperature in Kelvin.
• From Rankine: Subtract 764.84 from the temperature in Rankine, then multiply the result by 5, finally divide by 9 (alternatively, multiply the result by .5556).
• From Réaumur: Multiply the temperature in Réaumur by 10, divide the result by 8 (alternatively multiply by 1.25), finally add 273.15.

Conversion from Kelvin

• To Fahrenheit: Subtract 273.15 from the temperature in Kelvin, multiply by 9, then divide by 5 (alternately, multiply by 1.8), finally add 32.
• To Celsius: Subtract 273.15 from the temperature in Kelvin to get the temperature in Celsius.
• To Rankine: Multiply the temperature in Kelvin by 9, then divide by 5 (alternatively, multiply by 1.8), finally add 764.84.
• To Réaumur: Subtract 273.15 from the temperature in Kelvin, then multiply by 0.8 (or 4/5).

Conversion to Rankine

• From Fahrenheit: Add 459.69 to the temperature in Fahrenheit to get the temperature in Rankine.
• From Celsius: Multiply the temperature in Celsius by 9, divide the result by 5 (alternatively multiply °C by 1.8), then add 491.69.
• From Kelvin: Add 764.84 to the temperature in Kelvin, then multiply the result by 9, finally divide by 5 (alternatively, multiply the result by 1.8).
• From Réaumur: Multiply the temperature in Re by 9, divide the result by 4 (alternatively multiply by 2.25), add 32, finally add 459.67 (alternatively you may add 491.67 in one step).

Conversion from Rankine

• To Fahrenheit: Subtract 459.69 from the temperature in Rankine to get the temperature in Fahrenheit.
• To Celsius: Subtract 491.69 from the temperature in Rankine, multiply the result by 5, then divide by 9 (alternatively multiply the result by .5556).
• To Kelvin: Subtract 764.84 from the temperature in Rankine, then multiply the result by 5, finally divide by 9 (alternatively, multiply the result by .5556).
• To Réaumur: Subtract 32 from the temperature in Rankine, subtract 459.67 from the result (alternatively you may subtract 32+459.67 or 491.67 in one step), then multiply the result 9, divide the result by 4 (alternatively divide the result by 2.25).

Conversion to Réaumur

• From Fahrenheit: Subtract 32 from the temperature in Fahrenheit, multiply the result by 9, then divide by 4 (alternatively divide the result by 2.25).
• From Celsius: Multiply the temperature in Celsius by 4, divide the result by 5 (alternatively multiply °C by 0.8). That’s it!
• From Kelvin: Subtract 273.15 from to the temperature in Kelvin, then multiply the result by 4, finally divide by 5 (alternatively, multiply the result by 0.8).
• From Rankine: Subtract 32 from the temperature in Rankine, then subtract 459.67 (alternatively, you may subtract 491.67 in one step), multiply the result by 9, divide by 4 (alternatively you may divide the result by 2.25).

Conversion from Réaumur

• To Fahrenheit: Multiply the temperature in Réaumur by 9, then divide by 4 (alternatively multiply the temperature in Réaumur by 2.25), finally, add 32.
• To Celsius: Multiply the temperature in Réaumur by 10, divide by 8 (alternatively multiply the temperature in Réaumur by 1.25).
• To Kelvin: Multiply the temperature in Réaumur by 10, divide by 8 (alternatively multiply the temperature in Réaumur by 1.25). Finally, add 273.15.
• To Rankine: Multiply the temperature in Réaumur by 9, divide by 4 (alternatively multiply the temperature in Réaumur by 2.25), add 32, finally, add 459.67 to the result (alternatively you may add 491.67 in one step).

Temperature Conversion Equation

Equations also express the steps needed to convert temperature from one scale to the other. They are your quick reference whenever you need them.

Convert from Fahrenheit to the other scales:
• To Celsius: (F – 32) / 1.8 = °C
• To Kelvin: (F + 459.67) / 1.8 = K
• To Rankine: F + 459.67 = °Ra
• To Réaumur: (F – 32) / 2.25 = °Re

Convert from Celsius:
• To Fahrenheit: (C × 1.8 + 32) = °F
• To Kelvin: C+ 273.15 = K
• To Rankine: C × 1.8 + 32 + 459.67 = °Ra
• To Réaumur: C × 0.8 = °Re

Convert from Kelvin:
• To Fahrenheit: K × 1.8 – 459.67 = °F
• To Celsius: K – 273.15 = °C
• To Rankine: K × 1.8 = °Ra
• To Réaumur: (K – 273.15) × 0.8 = °Re

Convert from Rankine:
• To Fahrenheit: Ra – 459.67 = °F
• To Celsius: (Ra – 32 – 459.67) / 1.8 = °C
• To Kelvin: Ra / 1.8 = K
• To Réaumur: (Ra – 32 – 459.67) / 2.25 = °Re

Convert from Réaumur:
• To Fahrenheit: Re × 2.25 + 32 = °F
• To Celsius: Re × 1.25 = °C
• To Kelvin: Re × 1.25 + 273.15 = K
• To Rankine: Re × 2.25 + 32 + 459.67 = °Ra


You might be familiar with the two main temperature scales – Fahrenheit and Celsius – of the five scales developed to measure how hot or cold things are. The formulas and equations connected to each scale are used when converting temperature values. They are easy and fun to use for your conversions. Use them as a reference whenever you need to.

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