Meat Thermometer Calibration If you’re unsure your digital meat thermometer is accurate, there are ways to calibrate it. In the first method, fill a glass with iced water, let it stand for 30 seconds, and insert the probe into it, the thermometer should read 0 – 1ºC or 32 – 33.8ºF. The second method is, to boil a pot of water with the water boiling insert the probe, the thermometer should read 99 – 100ºC or 210 – 212ºF. Make sure the tip of the probe doesn’t touch the bottom of the pot, this will give a false reading. Be mindful - this method will not work at high altitudes as the water boils at a lower temperature.