Kelvin to Fahrenheit Converter

Use this free Kelvin to Fahrenheit converter to change a temperature from kelvin to degrees Fahrenheit. Type a number in the Kelvin box and the Fahrenheit answer appears as you type, with the working shown straight to Fahrenheit and also through Celsius. You can also type in the Fahrenheit 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 K, popular kelvin values, room temperature in kelvin, key temperatures such as absolute zero and the boiling point of water, and how the kelvin scale compares with Fahrenheit. It is free and instant, and your numbers stay in your browser.

How to convert Kelvin to Fahrenheit

A kelvin is 1.8 times a Fahrenheit degree, and kelvin starts at absolute zero, which is −459.67 °F. So you multiply by 9/5 (that is 1.8) and then subtract 459.67.

For 300 K: 300 × 9 ÷ 5 = 540, and 540 − 459.67 = 80.33 °F. For 273.15 K, the freezing point of water: 273.15 × 9 ÷ 5 = 491.67, and 491.67 − 459.67 = 32 °F. For 373.15 K, the boiling point at sea level: 373.15 × 9 ÷ 5 = 671.67, and 671.67 − 459.67 = 212 °F.

Two ways, the same answer

You can also change to Celsius first and then to Fahrenheit: °F = (K − 273.15) × 9/5 + 32. For 300 K: 300 − 273.15 = 26.85 °C, 26.85 × 9 ÷ 5 = 48.33, and 48.33 + 32 = 80.33 °F. Both ways give exactly the same number. The direct way is one step less, and the Celsius way helps if you also want the Celsius value. Do not just multiply the kelvin number by 1.8 and add 32, because kelvin does not start at the same place as Celsius.

The kelvin temperature scale

Kelvin is the SI unit of temperature. It starts at absolute zero, 0 K, the lowest temperature possible, so it has no negative values. A change of 1 K is the same as a change of 1 °C, and 1.8 °F. Water freezes at 273.15 K and boils at about 373.15 K, which is 100 steps in kelvin and 180 steps in Fahrenheit.

Common conversions

0 K is −459.67 °F, 1 K is −457.87 °F, 100 K is −279.67 °F, 273.15 K is 32 °F, 293.15 K is 68 °F, 298.15 K is 77 °F, 300 K is 80.33 °F, 310.15 K is 98.6 °F and 373.15 K is 212 °F. The chart above lists more, from absolute zero to 1,000 K, and the table of popular values shows the ones people look up most.

Room temperature in kelvin

Room temperature is often quoted as about 20 to 22 °C, which is 293.15 to 295.15 K, or 68 to 71.6 °F. There is no single official figure, so use the value that your book, lab or instructions give.

Absolute zero

Absolute zero is 0 K, which is −459.67 °F and −273.15 °C. Nothing can be colder, so the converter does not accept anything below it.

Why kelvin has no degree sign

Kelvin is written with just the letter K: 300 K, not 300 °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: 80.33 °F.

Fahrenheit to Kelvin

To go the other way, add 459.67 and multiply by 5/9: 77 °F is (77 + 459.67) × 5 ÷ 9 = 298.15 K. You can do it here by typing in the Fahrenheit box, or use the Fahrenheit to Kelvin converter, which has its own chart. For other pairs, use the Kelvin to Celsius converter or the Celsius to Fahrenheit converter, and for all four scales use the Temperature Converter.

Spelling

The correct spellings are kelvin and Fahrenheit. Many people type "kalvin" or "farenheit", and this page is for them too.