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How Accurate are Non-Contact Thermometers?

How Accurate are Non-Contact Thermometers?

How Accurate are Non-Contact Thermometers?

It seems really simple: you point a laser at someone’s forehead and press a button. In a split second, you have a temperature reading. The simplicity of non-contact thermometers has got some people wondering how accurate they really are? 

Find out about non-contact thermometer accuracy in this article.

How accurate are non-thermometers?

Are Non-Contact Thermometers Accurate

For those wondering ‘are contactless thermometers accurate?’ the answer starts with how they work.

Contactless thermometers use infrared radiation to determine temperature. Temperature directly correlates with temperature: the hotter something is, the more infrared radiation it will emit. For a contactless thermometer to read a temperature, infrared radiation is focused through a lens in the device onto a detector called a thermophile, which converts infrared radiation/heat into an electrical charge that can be translated into a numerical temperature that we read.

Although it’s a bit more complicated, infrared thermometers are still experiencing the heat of a temperature and translating this into a format we can read. So, Infrared thermometer accuracy for body temperature is much the same as any other method of measuring temperature This also means contactless thermometers are completely safe to use. They do not emit any harmful energy. They only read infrared radiation, something that is emitted by all things on earth.

Read more about exactly how a contactless thermometer works and what happens inside them in our blog.

Infection control check with staff member using infrared

How Accurate is a Laser Thermometer

So, how accurate are laser thermometers? Non-Contact Digital Thermometer Accuracy has been proven to be better than other types of thermometers in some cases.

In a study conducted on the clinical accuracy of a non-contact infrared skin thermometer in paediatric practice, contactless thermometer accuracy was tested against a rectal thermometer (known to be the most accurate type of thermometer) and a temporal artery thermometer (one that makes contact with the skin of the forehead).

The results of the study found the difference between the rectal thermometer reading and the contactless thermometer reading was 0.01°C, whereas the difference between the rectal thermometer reading and the temporal artery thermometer reading was 0.27°C. The study concludes that a “non-contact infrared thermometer is a reliable, comfortable and accurate option for measurement of temperature and is very useful for the screening of fever”.

Applications and Accuracy

Thermometers are calibrated to detect temperatures within a specific range. The further outside of a thermometer’s measurement range a temperature is, the less accurate it will be. And considering the difference between a normal, healthy human temperature of 37°C and a fever of 38°C is only 1 degree there’s not lots of room for error. This is why it’s important to only use a contactless thermometer (or any thermometer) for its intended purpose. 

When looking for the right product, it’s important to remember that no infrared forehead thermometer accuracy will ever be absolute. All contactless thermometers will have a minute discrepancy in temperature measurement. It is simply not possible to have an absolutely accurate measurement, even when using a rectal thermometer. The Berrcom Contactless Thermometer is a high accuracy infrared thermometer, having a tested accuracy of:

  • 32.0°C - 34.9°C: ±0.3°C
  • 35.0°C - 42.0°C: ±0.2°C
  • 42.1°C - 43.0°C: ±0.3°C

When we consider that the difference between a normal temperature and a fever is 1°C, a discrepancy of 0.2°C at the maximum is nowhere near enough to produce an incorrect reading.

Close up of using a non-contact thermometer

What can Affect Contactless Thermometer Accuracy?

While no contact thermometer accuracy has been proven, this is only valuable when the device is being used correctly. There are multiple variables that could lead to an inaccurate reading, such as:

  • Aiming the device as a body part other than the forehead such as the chest or arm.
  • Aiming the device at an incorrect angle (the thermometer should be aimed at 90° to the surface or subject’s forehead.
  • Moving the thermometer before a result is displayed.
  • Taking a reading near a draft such as that from an air conditioning unit or an open window.
  • Taking a reading when the subject is not at their normal body temperature, for example after having performed exercise.
  • Taking a reading immediately after the device has entered a new environment with a drastically different temperature, for example, by taking it outdoors (allow 30 minutes for adjustment).

Using a contactless thermometer correctly is critical to getting an accurate reading. In our blog, we cover how to use a contactless thermometer in steps.

Unregulated Products

Another variable that can affect infrared thermometer body temperature accuracy is the quality of the device being used. 

In July 2021 the Medicines and Healthcare products Regulatory Agency commented that it had “become increasingly aware of infrared thermometers being sold in the UK that do not comply with the regulations” and released guidance on how to identify infrared thermometers that have passed regulations to be sold on the UK market.

Digital infrared thermometer accuracy and safety are taken into consideration when products are reviewed for release to the UK market, so having a product up to this standard of quality is important. Look for the following signifiers to tell that the product you are buying is approved for use by UK consumers.

Find these on the product or packaging:

1. Address and name of the manufacturer.

2. The address and name of the European representative or Responsible person if not made in the UK.

3. The CE mark and a four-digit number identify the notified body responsible for assessing the device.

4. The model number and name of the product.

5. The lot or batch number.

Some companies will try to trick consumers by making their products seem legitimate. Look closely at the information on the product or packaging to determine whether it is genuine. You should be suspicious of:

1. A CE mark without a four-digit number.

2. A CE mark that is not in the right format.

3. Lack of details about an EU or UK representative. For example, the product might just say ‘Made in China’ with no other information. 

Check that the CE mark is correctly formatted:

CE mark


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