There are several ways to check your infrared thermometer’s accuracy. One is by mixing water and crushed ice until the consistency is slurry. Then measure it to see if your thermometer gives a zero-degree Celsius reading. The closer it is to zero degrees, the more accurate your thermometer is. Another is using a device with a solid non-glossy matte base, and high emissivity called an infrared comparator cup. Compare the temperatures between your infrared thermometer and the calibrated reference thermometer with the aid of the cup.