Infrared vs Digital Thermometers – What is The Difference?

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It wasn’t that long ago when buying a thermometer was a simple thing. Options were limited and a simple digital thermometer, meant to be placed under the tongue, was the only available type. Now, though, home thermometers come in all shapes and sizes, and buying one has become a lot more complicated.

Fortunately, you can still boil this decision down to one major choice: infrared thermometer vs digital thermometer. Infrared thermometers are relatively new, especially the ones sold for home use, but digital thermometers have been around for a while now. They each have their pros and cons, and choosing the right thermometer for your needs requires weighing a few different variables.

Thermometers: Know Why You’re Buying it

It seems obvious, but before you buy a thermometer think about what you’ll be using it for. A digital stick thermometer is a useful tool when you’re sick, but it’s useless if you’re trying to determine if your meat has been cooked properly. You need an instant read meat¬†thermometer for that, and neither of those can tell you what temperature your oven or grill really is.

Likewise a temporal artery thermometer generally can’t be used in the same way as a digital laser infrared thermometer. Both use infrared sensors to measure temperature, but in different ways and for a different purpose.

So, before you start browsing for a new thermometer, know what you need. A medical thermometer is designed for taking a person’s temperature, while culinary thermometers are mainly for measuring the temperature of a cooking surface or food. You can find digital and infrared thermometers in both categories.

Digital Thermometers

A quick Google search for digital thermometers will mainly yield results for instant read digital thermometers meant for cooking. These are excellent tools that allow for perfectly cooked foods every time, but they aren’t well suited to medical purposes. While they’ll definitely give you an accurate temperature reading, the temperature probes on them are quite sharp, since they have to pierce into the middle of large pieces of food.

That sharp tip is not something you want in your mouth or your child’s mouth. Medical thermometers meant for oral or rectal use have safe, rounded tips. Digital thermometers have been standard for home medical use for years now. You can check out Forehead Thermometer review.

How a Digital Thermometer Works

Digital thermometers are built around a sensor that responds to temperature. These sensors are called thermoresistors. Often these are simple glass beads with two wires attached. The “resistance” mentioned earlier is the resistance of the material to the flow of electricity. As it increases or decreases in temperature, the rate at which electricity flows from one wire to the other through the glass is changed.

That change in resistance is very predictable, meaning we know exactly how each change in temperature will affect the flow of electricity. This allows the small computer in the thermometer to quickly calculate the temperature based on how much the flow of electricity has sped up or slow down. It is a very accurate and reliable process.

Advantages of digital thermometers

Digital thermometers are widely considered the best thermometers you can get. Here are the reasons why:

  • Digital medical thermometers can record a temperature from the mouth, armpit, or rectum in a minute or less
  • Digital thermometers can be used for newborns, children, and adults
  • Very accurate
  • For non-medical uses temperatures can be read instantly, and are much more accurate than analog thermometers
  • Quality digital thermometers are very affordable

Disadvantages of digital thermometers

Digital thermometers aren’t perfect. If they were, other types of thermometer wouldn’t exist. Here are the drawbacks to digital thermometers:

  • Can be uncomfortable to use, especially for children
  • Children in particular may have a hard time keeping their mouth closed long enough to get an accurate reading
  • If you’ve recently eaten or had something to drink, you’ll need to wait fifteen minutes before taking your temperature to get an accurate reading.
  • Since they require direct contact to use, there could be potential hygiene issues.

Digital thermometers are widely available, cheap, reliable, and easy to use. While they do have their drawbacks, they also have a lot going for them. You can’t go wrong with a digital thermometer.

Infrared Thermometers

Infrared thermometers are newer, at least for home use. Like digital thermometers, there are models meant for medical use (taking a person’s temperature) and culinary or practical use (measuring the temperature of an oven, grill, or other cooking surface).

While you would never want to stick a meat thermometer into your mouth to check your temperature, you probably could safely measure your temperature with any infrared thermometer, regardless of it’s intended purpose. The biggest difference between infrared thermometers designed for medical use and the ones meant for culinary use is that the latter are designed to measure and withstand much higher heat. These thermometers have to measure heat in hundreds of degrees. In fact, they may struggle to accurately measure something as low as human body heat.

Likewise, an infrared thermometer designed for measuring human body heat may struggle to hold up to the intense heat of a kitchen, and is best used only for medical purposes.

Infrared thermometers have been used by doctors for a long time- if you can remember the doctor taking your temperature through your ear, that was an infrared thermometer like this one. Since children and infants often find the sensation of having the thermometer in their ear very unpleasant, these thermometers didn’t catch on at home.

The development of forehead thermometers changed that. These thermometers are also infrared thermometers, but they can measure body temperature on the forehead, or more accurately in the temporal artery. This is a completely comfortable process, which makes it very easy to take a child’s temperature. Because it’s such a kid-friendly technique, it’s becoming popular as an in-home thermometer.

How Infrared Thermometers Work

To understand infrared thermometers, you need to understand black body radiation. Everything warmer than absolute zero (read: pretty much everything) has molecules vibrating. Heat is the result of these vibrating molecules. They also generate infrared radiation, which is a spectrum of light that isn’t visible to the human eye.

Infrared light is perhaps most famous from technology like night-vision goggles, which sense infrared radiation and allow the wearer to see at night. Everything generates infrared radiation, and the hotter an object is, the more infrared radiation it will emit.

An infrared thermometer works by measuring the amount of infrared radiation being generated. Infrared thermometers use a lens to concentrate the infrared light onto a sensor called a thermopile, which converts the light into heat. That heat is turned into electricity, and the amount of electricity generated is used to measure the temperature of the object.

Ear drum thermometers work because the ear drum is about the same temperature as the inside of the body, but the ear drum itself is very sensitive and touching it would be painful. The infrared thermometer can instead measure the temperature of the eardrum from a short distance (less than an inch) away. Other infrared thermometers measure the infrared radiation coming off your body- specifically the temporal artery- to determine body temperature.

In the case of industrial or culinary thermometers, infrared thermometers measure the infrared light generated by a cooking surface or a fire. It’s a common misconception that the laser on these thermometers is what’s measuring the temperature, but actually these are only used to help aim the thermometer accurately.

Advantages of Infrared Thermometers

While they still aren’t as widespread as digital thermometers, infrared thermometers are very popular and becoming more common. Here are the biggest advantages of infrared thermometers:

  • No physical contact needed; very comfortable and very safe
  • Temperature readings are instant
  • Can be used with newborns, infants, children and adults
  • Very accurate readings

Disadvantages of Infrared Thermometers

Despite their impressive benefits, infrared thermometers are not perfect. Here are the biggest drawbacks of infrared thermometers:

  • They tend to be very expensive
  • Ear thermometers can be uncomfortable

Infrared thermometers are, generally, just as accurate as their digital counterparts and even easier to use, but the cost can make them impractical.

Is Infrared Better?

The short answer is: maybe. It really depends on how you’re using your thermometer. If you need to measure the temperature of a thick steak, infrared is not helpful. It can only tell you the temperature of the outside of the steak. You need a digital thermometer for this job.

For body temperature, an infrared thermometer is usually better. Both the ear drum and the blood flowing through the temporal artery will give an accurate reading of internal body temperature. Most importantly, you’ll get that reading quickly and with minimal discomfort. In fact, the “forehead” thermometers are so easy to use and reliable that, if they were cheaper, it would be difficult to recommend anything else.

There’s no doubt that infrared has its advantages, especially if you need to take a child’s temperature. In fact, for children, it’s probably worth the added expense to buy an infrared thermometer that can measure from the temporal artery. These thermometers are very sanitary, cause no discomfort at all, and give an accurate reading each time.

A good way to understand it is this: in any situation in which you want to record a temperature from a distance, you want an infrared thermometer. At times when you need to check the internal temperature of something or don’t need to measure from a distance, digital is better.

Is Price the only Advantage For Digital Thermometers?

Not at all, but it is a big advantage. You can walk into any nearby pharmacy and find a quality, reliable digital thermometer at a price you can afford. The same simply isn’t true of infrared thermometers. The biggest weakness of the digital thermometers is also, at times, it’s biggest advantage.

A digital thermometer has to be in physical contact with whatever it is measuring. This can make them more difficult and uncomfortable to use compared to infrared thermometers, but in some cases it’s a distinct advantage. For one thing, it allows for more precision.

If you’re using it to measure the temperature of food, yo can check the temperature in multiple spots to ensure that the food is cooking evenly. Digital thermometers are best for measuring the temperature in an oven, grill or smoker, especially since the probe can be left in to measure temperature over time.

For personal medical use, a digital thermometer is just as accurate as infrared, but it’s easier to find, cheaper to buy, and smaller. That makes it easier to use and store, without suffering any loss in accuracy. These are all very strong reasons for choosing a digital thermometer.

Conclusion

As you can see, there are both advantages and disadvantages for infrared and digital thermometers. While infrared thermometers are often much easier to use, digital thermometers aren’t exactly complicated to begin with. Infrared thermometers are definitely more comfortable, but for most adults a digital thermometer is that uncomfortable anyway.

If you already have a digital thermometer that you don’t mind using, upgrading to an infrared one is probably not worth the money for you. It won’t take more accurate readings and the advantages that you gain in comfort and ease-of-use are minimal.

That said, if you have a child at home and you need to take their temperature, upgrading to infrared could be worth the money. Children are much more prone to finding digital thermometers unpleasant, and an infrared thermometer is not only a non-contact thermometer, it also takes the reading very quickly, making it much easier to use with kids.

For non-medical uses, infrared thermometers offer the advantage of taking a temperature from a distance, but that’s it. They’re less useful for measuring the temperature of food or the interior of the oven, but they can tell you how hot a frying pan is or how hot the fire in the grill is.

It’s hard to recommend one or the other, since both infrared and digital have their uses. You need to choose the thermometer that’s best for your needs. We hope that now you have all the information you need to make that choice.

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