Temperature and temperature differences

Temperature scales do not share the same zero. Ordinary temperature conversion needs both a scale factor and an offset.

Absolute readings

°F = °C × 9/5 + 32
K = °C + 273.15

0 °C equals 32 °F and 273.15 K. The absolute-zero boundary is 0 K, −273.15 °C or −459.67 °F. UnitTidy rejects absolute values below that boundary.

Changes and intervals

For a rise or fall in temperature, select the Δ option. The offset disappears: a change of 1 °C equals a change of 1 K or 1.8 °F. Negative differences are allowed, so a fall of 10 °C becomes −18 °F. A negative difference is not an absolute temperature below zero kelvin.

Read the result in context

Converting a thermometer reading does not improve its calibration or resolution. Batch conversions use the same Δ selection for every row. Switch off Δ before converting a weather forecast or a thermostat reading.

Celsius to Fahrenheit reference table · NIST conversion factors