5 Things to Consider When Selecting an Infrared Thermometer

Infrared ThermometerAn 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 have the right tool for the job before you make that investment.
  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.

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

Terms and Definitions


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.

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.

Learn more about infrared thermometers and the many options available at Grainger.