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(Version 4 of this Technical Guide includes a description of the uncertainties in the calibration corrections.)

The advent of low-cost handheld infrared thermometers, which make non-contact measurements in the range –50 °C to 500 °C, has led to a proliferation of the thermometers in the food, building, and low-temperature processing industries. However, these instruments are not as simple to use as they first appear due to systematic effects related to emissivity, reflections, and the temperature of the thermometer itself. This guide explains how to calibrate low-temperature infrared thermometers and gives methods for correcting for the systematic effects.