Many thermometers can be calibrated if you find that it isn't accurate. Check the manufacturer's directions for the specific thermometer that you have for how to calibrate your make and model. Some thermometers, like the integrated probe that comes with some models of the Ninja Foodi Indoor Grill and Ninja Foodi XL oven, cannot be calibrated. If your appliance has an integrated thermometer and it cannot be calibrated by you, then you can make adjustments in cooking temperatures to compensate for the inaccuracy or if it is very inaccurate, I would contact the manufacturer to see about an exchange.