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How to Pick a High Quality Infrared Thermometer

Revised: 9/6/19
Grainger Editorial Staff

How do infrared thermometers work?

An infrared thermometer uses a built-in laser to detect the temperature of an object that is out of reach or at a distance, for example an HVAC system. Here are some specific questions you should ask yourself to ensure you pick a high quality infrared thermometer for the job before you make that investment.

Infrared Thermometer
  1. What temperature range is required?
  2. What distance will the user be from the object(s) being tested (Focus Spot Size and Distance)?
  3. Do application(s) require adjustable emissivity (see definitions)?
  4. Do application(s) require a surface/immersion probe (for user adjustments to emissivity)?
  5. Do you require laser sighting, data hold, data logging, and high/low alarm?

Common Specifications of an Infrared Thermometer

Here are some specifications that can help you narrow down your choices and choose a high quality infrared thermometer:

  • Temperature Range and Resolution
  • Focus Spot Size and Distance
  • Accuracy
  • Emissivity
  • Laser Sighting
  • Data Logging
  • Display Type

Terms and Definitions

What is Emissivity?

The measure of a surface's ability to emit long-wave infrared radiation, relative to a black body (which theoretically emits at 100% or 1.0). The emissivity of an object depends upon its material and surface texture. For example, a given polished metal may have an emissivity value of 0.20 and wood a value of 0.95.

What is Focus Spot Size And Distance?

Indicates the diameter of the focal point at a given distance. For example, 1" @ 12" indicates that a thermometer focuses on a 1" diameter circular area 12" away from the thermometer.

Convergence Feature dual lasers which converge to a single point, a 1" diameter around that point is your measurement area.

Coaxial 3 Dot - Laser sighting shows both center and edge of area being measured regardless of the distance from target.


The information contained in this article is intended for general information purposes only and is based on information available as of the initial date of publication. No representation is made that the information or references are complete or remain current. This article is not a substitute for review of current applicable government regulations, industry standards, or other standards specific to your business and/or activities and should not be construed as legal advice or opinion. Readers with specific questions should refer to the applicable standards or consult with an attorney.


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