Are infrared thermometers accurate? Can you use them on people? Let’s go over how to check a temperature with an IR thermometer; but first, let’s discuss how infrared thermometers work.
Electromagnetic radiation is a type of energy that exists all around us. It is measured by wavelengths on a spectrum, with visible light falling somewhere in the center. The human eye can only detect wavelengths from about 380 to 700 nanometers, which is why we can only see part of the spectrum. The rest of the light is invisible to us, but it still exists.
All surfaces emit an invisible spectrum of light. Warm things emit infrared light. Infrared thermometers measure temperature by measuring the infrared radiation emitted by a certain surface. But to do this accurately, the emissivity of a surface must be determined. Emissivity measures how effectively a surface can emit energy as infrared radiation on a scale ranging from 0 to 1, with 0 being a perfect reflector and 1 being an object that absorbs all incoming radiation without reflecting any. More reflective objects tend to have lower emissivity values.
Infrared thermometers are typically set at a default emissivity setting of 0.95.
Are IR Thermometers Accurate?
As mentioned above, you must first set the emissivity of a surface to determine an accurate temperature. If you are looking to use an infrared thermometer as a tool, this is particularly important depending on the job you are trying to accomplish. Infrared thermometers are commonly used for safety purposes to measure the surface temperature of objects—especially objects that are just out of reach, moving, or delicate electronics. With help from the chart below, you can ensure you are using your IR thermometer for the most accurate measurement.
| Material | Emissivity |
|---|---|
| Polished aluminum | 0.05 |
| Typical foods | 0.8-0.95 |
| White paper | 0.09 |
| Glass/Frosted glass | 0.94 |
| Clear plastic | 0.94 |
| Black paper | 0.94 |
| Black plastic | 0.95 |
| Black electrical tape | 0.95 |
| Concrete | 0.95 |
| Asbestos board | 0.96 |
| Ice | 0.97 |
| Water | 0.98 |
| Skin | 0.98 |
Can You Use IR Thermometers on Humans?
You can use IR thermometers on people and they can be particularly useful in highly infectious situations since they don’t require contact in order to get a temperature. According to the Food and Drug Administration (FDA), infrared thermometers can reduce cross-contamination risk and minimize the risk of spreading disease.
How to Check Temperature of Other Surfaces with an IR Thermometer
IR thermometers that are intended for more work-oriented purposes are not accurate for use on humans, although they work in a similar way. This type of infrared thermometer is useful for checking temperatures during car maintenance, monitoring the temperature of an oven or air conditioner, food preparation, and fire prevention. They typically include options for adjusting emissivity levels and can measure temperatures that range anywhere from -58°F to more than 2,800°F. Once your settings have been adjusted, you can usually just point at your selected item and press a button to retrieve the temperature.
The science of measuring the electromagnetic radiation of an object or even the surface of the human forehead is a fascinating thing to consider. Understanding how to accurately use infrared thermometers to obtain a temperature can be useful in a variety of settings, especially when you’re trying to gather a temperature without making contact.
Product Compliance and Suitability
The product statements contained in this guide are intended for general informational purposes only. Such product statements do not constitute a product recommendation or representation as to the appropriateness, accuracy, completeness, correctness or currentness of the information provided. Information provided in this guide does not replace the use by you of any manufacturer instructions, technical product manual, or other professional resource or adviser available to you. Always read, understand and follow all manufacturer instructions.