Food Thermometer Calibration Calculator

Ice water sits at a fixed 32 degF everywhere, since it's governed by water's freezing point, which atmospheric pressure barely affects. Boiling water's temperature, by contrast, is set by the point where vapor pressure matches atmospheric pressure -- and atmospheric pressure drops steadily with elevation, so the true boiling point drops too. This calculator adjusts the boiling-point target down by roughly 1 degF for every 500-550 feet of elevation to account for that, while the ice-point target never changes.

FDA Food Code §4-203.11(B) sets the benchmark at accuracy within +/-2 degF of the true temperature for thermometers scaled only in Fahrenheit. This calculator flags "Within +/-2°F Tolerance" as No whenever the absolute error between the reading and the known ice-point or elevation-adjusted boiling-point target exceeds that 2-degree window, signaling the thermometer needs recalibration or replacement before it's trusted for food safety checks.

Apply the Correction Offset this calculator reports to every future field reading until the thermometer is fixed, and recalibrate or replace it as soon as practical. Many dial (bimetallic) thermometers have a calibration nut under the dial face that can be adjusted to zero out the error directly; most digital instant-read thermometers cannot be field-adjusted this way and should simply be replaced once they drift outside tolerance.

No -- the target temperature (32 degF for Ice Point, or the elevation-adjusted figure for Boiling Point) is a property of the calibration medium and elevation only, not of what the thermometer happens to display. The reading is compared against that independently-determined target to compute the error; it never feeds back into the target itself.