Use this free Fahrenheit to Kelvin converter to change a temperature from degrees Fahrenheit to kelvin. Type a number in the Fahrenheit box and the kelvin answer appears as you type, with the working shown straight to kelvin and also through Celsius. You can also type in the Kelvin box to go the other way. Pick how many decimals to round to and copy a link to your conversion. Tables list a chart from absolute zero to 1,000 °F, popular Fahrenheit values, room temperature in kelvin, key temperatures such as absolute zero and the boiling point of water, and how the two scales compare. It is free and instant, and your numbers stay in your browser.
How to convert Fahrenheit to Kelvin
Kelvin starts at absolute zero, which is −459.67 °F, and a kelvin is 1.8 times a Fahrenheit degree. So you add 459.67 and then scale by 5/9 (or divide by 1.8).
K = (°F + 459.67) × 5/9For 77 °F: 77 + 459.67 = 536.67, and 536.67 × 5 ÷ 9 = 298.15 K. For 32 °F, the freezing point of water: 32 + 459.67 = 491.67, and 491.67 × 5 ÷ 9 = 273.15 K. For 212 °F, the boiling point at sea level: 212 + 459.67 = 671.67, and 671.67 × 5 ÷ 9 = 373.15 K.
Two ways, the same answer
You can also change to Celsius first and then add 273.15: K = (°F − 32) × 5/9 + 273.15. For 77 °F: 77 − 32 = 45, 45 × 5 ÷ 9 = 25 °C, and 25 + 273.15 = 298.15 K. Both ways give exactly the same number. The direct way is one step less, and the Celsius way helps if you already know the Celsius value.
Why kelvin has no degree sign
Kelvin is the SI unit of temperature, so it is written with just the letter K: 298.15 K, not 298.15 °K. It used to be called "degree Kelvin", and many people still say degrees kelvin, but the unit is simply the kelvin. Fahrenheit keeps the degree sign: 77 °F.
Common conversions
32 °F is 273.15 K, 50 °F is 283.15 K, 60 °F is 288.71 K, 69 °F is 293.71 K, 70 °F is 294.26 K, 77 °F is 298.15 K, 98.6 °F is 310.15 K, 100 °F is 310.93 K and 212 °F is 373.15 K. The chart above lists more, from absolute zero to 1,000 °F, and the table of popular values shows the ones people look up most.
Room temperature in kelvin
Room temperature is often quoted as about 68 to 72 °F, which is 293.15 to 295.37 K. There is no single official figure, so use the value that your book, lab or instructions give.
Absolute zero
Absolute zero is the lowest temperature possible: 0 K, which is −459.67 °F and −273.15 °C. Kelvin starts there, so it has no negative values, and the converter does not accept anything below it.
When Fahrenheit and kelvin show the same number
The Fahrenheit number and the kelvin number are the same at about 574.59: 574.59 °F is 574.59 K. Below that, the kelvin number is smaller, and above it, the Fahrenheit number is larger. It is only a curiosity, because the scales have different zeros and different sized degrees.
Kelvin to Fahrenheit
To go the other way, multiply by 9/5 and subtract 459.67: 300 K is 300 × 9 ÷ 5 − 459.67 = 80.33 °F. You can do it here by typing in the Kelvin box, or use the Kelvin to Fahrenheit converter, which has its own chart. For other pairs, use the Fahrenheit to Celsius converter, the Celsius to Kelvin converter or the Kelvin to Celsius converter, and for all four scales use the Temperature Converter.
Spelling
The correct spellings are Fahrenheit and kelvin. Many people type "farenheit" or "kalvin", and this page is for them too.
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