Temperature conversion: Celsius, Fahrenheit and kelvin

3 units, with K as the base. For a change in temperature rather than a reading, see the temperature difference table, where a change of 1 °C equals a change of 1 K.

These scales need an offset

Temperature does not convert by multiplication alone. Each scale starts at a different zero, so a conversion is a factor and then an addition, and treating it as a factor is the most common error with this quantity. There is no factor table below for that reason.

Common conversions

Celsius to Fahrenheit

°F = °C × 9/5 + 32
°C = (°F − 32) × 5/9

Celsius to kelvin

K = °C + 273.15
°C = K − 273.15

Fahrenheit to kelvin

K = (°F − 32) × 5/9 + 273.15
°F = (K − 273.15) × 9/5 + 32

Common temperatures

Common temperatures, in °C, °F, K
°C	°F	K
−40	−40	233.15
0	32	273.15
20	68	293.15
25	77	298.15
37	98.6	310.15
100	212	373.15

Worked examples

25 °C in °F
= 25 × 9/5 + 32
= 77 °F

98.6 °F in °C
= (98.6 − 32) × 5/9
= 37 °C

Convert a number

The formulas give the method; the unit converter does the arithmetic, remembers the units you picked, and turns any conversion into a link you can share.