Degrees Fahrenheit to kelvin (°F to K)

K = °F × 0.5555555556 + 255.3722222. So 0 °F = 255.3722222 K and 100 °F = 310.9277778 K.

The formula

K = °F × 0.5555555556 + 255.3722222

Where the factor comes from — each unit by its definition, then its size in SI:

  • T(K) = (T(°F) + 459.67) × 0.5555555556
  • 1 K is the SI unit of temperature.

Gas laws and radiation formulas need absolute temperature in kelvin. Celsius and kelvin differ by an offset only; Fahrenheit differs in both offset and step size, so it is a formula, not a single factor.

Worked examples

  • Water freezing (0 °C): 32 °F = 273.15 K — 32 × 0.5555555556 + 255.3722222 = 273.15
  • Human body temperature (37 °C): 98.6 °F = 310.15 K — 98.6 × 0.5555555556 + 255.3722222 = 310.15
  • A baking oven: 350 °F = 449.817 K — 350 × 0.5555555556 + 255.3722222 = 449.817
  • A warm room: 68 °F = 293.15 K — 68 × 0.5555555556 + 255.3722222 = 293.15

Frequently asked questions

How many kelvin is 1 °F?

1 °F = 255.9277778 K. The rule is K = °F × 0.5555555556 + 255.3722222.

How do I convert kelvin back to degrees Fahrenheit?

Invert the rule: °F = (K − 255.3722222) / 0.5555555556.

°F to K conversion table

Degrees Fahrenheit (°F)Kelvin (K)
-40233.15
-20244.26111
0255.37222
10260.92778
20266.48333
32273.15
40277.59444
50283.15
60288.70556
68293.15
70294.26111
80299.81667
90305.37222
98.6310.15
100310.92778
150338.70556
200366.48333
212373.15
250394.26111
300422.03889
350449.81667
400477.59444
450505.37222
500533.15

Definitions: NIST Special Publication 811 (2008), Guide for the Use of the International System of Units, Appendix B — https://www.nist.gov/pml/special-publication-811 · BIPM, The International System of Units (SI Brochure), 9th edition (2019), Tables 2, 4 and 8 — https://www.bipm.org/en/publications/si-brochure. Machine value of the factor: 0.555555555556, offset 255.372222222.