How to Measure Body Temperature

How to Measure Body Temperature and Identify COVID-19

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In simple terms, body temperature is an indicator of how well your body can generate heat and how well the body can get rid of the same heat. A rise or dip in body temperature is an indicator of a variety of health factors, and informs the next steps, including whether or not to see a doctor.

A high temperature could signify a number of things, helping you determine whether you are simply overheated or are suffering from a fever. A lower body temperature than normal also help you determine factors like shock from trauma or an accident, and even hypothermia in extreme cases.

Whether it is for yourself, your kids or an adult you are taking care of, learning to take temperatures at home is important. This is especially so now that COVID-19 is making its way through the country. A fever is normally the first indicator of the symptoms, so it is necessary for everyone to have a thermometer kit around. Knowing how to use the kit to take your temperature helps you take the necessary steps towards getting help.

In this article, you will look at a few factors you need to know about measuring your body temperature, including the cases that should inform this step, the various methods you can use to measure your temperature and a breakdown of each method so you can determine which one you should use on a case-by-case basis.


How to Measure Body Temperature:

1. Orally

  • Disinfect the thermometer doing alcohol wipes or a cotton wool dipped in alcohol. Let it dry then rinse it in water.
  • Place the thermometer inside the mouth. Put it under the tongue for a more accurate reading.
  • Close the mouth. Let the thermometer stay in place for at least one minute. A digital thermometer will give a beep once the recommended time is up.
  • Remove the thermometer and read the temperature.
  • Disinfect the thermometer and put it back in storage.

2. Rectally

  • Disinfect the tip of the thermometer doing alcohol. Rinse with water once the alcohol has dried.
  • Lubricate the tip doing petroleum jelly. This ensures that insertion is painless.
  • Whether you are doing it to a baby or an adult, the knees need to be bent to ensure you open up fully.
  • Clean the pathway into the rectum. Presence of feces reduces the accuracy of results.
  • Insert up to one inch of the tip of the thermometer into the rectum.
  • Hold the thermometer in place around 1 minute, or until the thermometer gives a beep.
  • Remove the thermometer and read the temperature.
  • Learn How to use an ear thermometer

3. Tympanic

  • The ear has to be clean before this procedure. Ear wax affects the accuracy of the results. Take a Q-tip and gently clean the ear canal.
  • Make sure the tip of the thermometer is clean. Ensure that you do not use the same probe tip twice.
  • Pull back the ear gently so as to straighten the path from the outside of the ear to the eardrum.
  • Insert the thermometer gently into the ear canal until you reach the base.
  • Squeeze the button on the thermometer for one second.
  • Pull the thermometer back out of the ear and read the measurements.
  • Disinfect the thermometer and store it.

4. Axillary

  • Remove any cloth barrier between the thermometer and the skin. For an adult, you might need to put the thermometer through the top of the cloth they are wearing.
  • Place the thermometer in the middle of the armpit while the person has their arm raised.
  • Hold the thermometer in place as the person gently lowers their arm back in place.
  • Leave the thermometer in the armpit for up to 1 minute.
  • Remove the thermometer and take note of the readings.
  • Disinfect the thermometer and store it.

5. Temporal Artery

  • Hold the thermometer over the forehead for a few seconds.
  • Remove the thermometer and read the temperature on the LCD display.
  • Disinfect and store the thermometer.
  • Learn how to use a temporal thermometer

Why Measure Body Temperature

Your body temperatures are an indicator of many things, from your level of comfort in certain weather to the hormone levels in your body. Knowing the correct body temperature is an important gauge of where your health stands.

  • Fever: this is the most common reason why people measure the body temperature. A fever is an indicator of many health factors like infections, injury, and the effect of medicines on your body. An infection might increase your body temperature because your body is trying to fight it off, causing a fever. When you have an injury like burns or a heart attack, your body temperature is also going to be high, most likely due to the shock to your system. Underlying medical conditions like cancer and hyperthyroidism also raise your body temperatures because the body is trying to fight against the condition.
  • Hypothermia: While hypothermia comes with other indicators like shivering and confusion, the initial indicator is a low body temperature. Unknown to many, other factors like doing drugs, shock and infections can cause low body temperatures. When someone is in shock, maybe due to an accident, their body temperature can plummet sharply. The same thing happens to people with medical conditions like hypothyroidism and infections like sepsis. Measuring for low body temperature helps parents determine whether or not their newborns have an infection. Caregivers can also tell the medical condition of older adults by measuring for low temperatures.
  • Heatstroke: when you have a heatstroke, your body loses control of its temperature regulation, and therefore your temperatures keep rising. This can lead to shutdown of many organs, and may even lead to death. There are two types of heatstroke: classic heatstroke can build over a number of days and can happen even if one is not overly active or in an area that is too hot. When experiencing classic heatstroke, the body slowly loses the ability to sweat, a process that normally cools down the body to the average temperature range. Exertional heatstroke occurs when you work or exercise when temperatures are higher than usual. Even though you might sweat because of the exertion from work or exercise, the sweating is not enough to cool down the body, leading to a shutdown of your organs.

Facts About Body Temperature

There are two main types of body temperature and they vary according to the environment.

  • Core Temperature: your body’s core temperature is based on the temperature of the body’s mucous membrane. To establish the core temperature, you will need to insert a thermometer into the body, maybe through the esophagus or the urinary tract.
  • Surface Temperature: the surface temperature takes into account the level of heat inside the body and the temperature of the room. To get the surface temperature, you will use the thermometer on the surface of the skin e.g. under the armpit or forehead, or just inside your body e.g. rectum or ear.

The body has a range of temperatures under which normal functioning occurs. The average range for adults and children varies, and when the temperature falls within this range, there should be no cause for concern.

For adults, a range of 97 F to 99 F (36°C to 37.5°C) is normal.

Newborns and children have a significantly higher range of temperature, from between 97.9 F to 100.4 F (36.6°C to 38°C).

Where to Measure Body Temperature

Axillary: the axillary method of measuring temperature is probably the most comfortable method because it is not invasive. Anyone can take the measurement without the risk of infecting the other party because the thermometer is placed under the armpit. Many healthcare professionals use this method when measuring the temperatures of both adults and children.

If you use this method, keep in mind that the results will be a bit lower than the average temperature range because other factors like the temperature of the room affect the results. The normal temperature range for axillary measurement is between 94.46 F to 99.14 F for an adult.

Orally: oral temperature measurements are taken when the thermometer is placed inside the mouth, whether it is under the tongue (sublingual) or against the cheek (buccal). This method is preferred by parents and medical professionals when taking the temperature of young children. This method gives a normal range of 95.9 F to 99.5 F.


Tympanic: this measurement is given after inserting a thermometer into the ear canal. It is quick and very reliable, making it a popular method for use by physicians when measuring infants and young children. The normal temperature range when you use this method is between 95.9 F to 99.9 F.

Rectal: this method is considered the most reliable in gauging the body temperature. It is used both at home and by physicians to measure the temperature of children from birth onwards. However, it is a slightly invasive method that might make a few people queasy. Make sure you get instructions on how to do it correctly so as not to injure the patient.

The good news is, if you use this method, you are guaranteed a high degree of precision. The normal temperature range doing the rectal method is between 97.8 F to 100.4 F.

Temporal Artery: this is the least invasive method and most comfortable for both the person measuring and the one being measured. It involves placing a digital thermometer near or on the forehead and getting the readings from a digital display. It has a high degree of variation, which has put into question the accuracy of the measurements. The normal temperature range doing this method is 95.9 F to 99.3 F.

Types of Thermometers

Gone are the days of mercury thermometers. While you might find a few on the market, keep away from them whether you are taking the temperature for a child or an adult. Mercury is toxic and could have adverse effects due to poisoning.

Digital thermometers are popular because they are easy to use. They eliminate the hassle of having to read a scale in order to gauge the temperature, something that could lead to inaccurate readings especially if you are not a professional. Digital thermometers display the readings on a small LCD screen.

Types of Thermometers

Infrared technology is used in many thermometers. This protects the people the thermometer is used on from allergies due to interaction with chemicals. The infrared thermometer is commonly used in the temporal artery this thermometer which has two sensors. One sensor takes the highest temperature while the other records the temperature of the room. The difference between the values gives the body temperature.

Disposable thermometers are designed for only one use. Disposable thermometers come in handy and are best used to measure temperature doing the axillary or oral method.

Pacifier thermometers and plastic strips are a type that has grown in popularity in recent times. Their accuracy is not the best and many professionals advise against their use. If you are unsure about which type of thermometer to get for use at home, the best thing is to ask a professional like your child’s pediatrician or your local pharmacist.


Knowing how to measure body temperatures is a necessary skill. It helps you decide whether you need to take action and get to the hospital, or look for home remedies that will help lower the temperature to acceptable levels. If used well, this skill can be life-saving, whether you are taking care of a child or an adult who has been in an accident or experienced trauma.

There are many options to choose from when measuring body temperature: you can decide to do the temporal method or axillary measure when you are dealing with someone you are not comfortable with. The oral and rectal methods give more accurate results, and they can be used for infants and young children.

Make sure to disinfect the thermometer before and after every use. If you use disposable ones, make sure you dispose of them where children will not be tempted to play with them.

If you are not a doctor, make sure that you consult one if you notice the body temperature of the person you just measured is lower or higher than the normal range. Now that you know the range each method gives, you are better placed to make good judgment as to when to consult a physician.



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