About the °f to k calculation
Converting fahrenheit to kelvin is not a simple multiplication, because the two scales start from different zero points. One degree Fahrenheit corresponds to 255.928 kelvin, but that ratio does not hold at other values — the formula below is what you actually need. The everyday scale in the United States, where water freezes at 32° and boils at 212°. The SI temperature unit. It starts at absolute zero, so it never goes negative and takes no degree symbol.
Formula
K = (°F − 32) × 5/9 + 273.15Worked example
Converting 98.6 °F through the formula above gives 310.15 K.
Frequently asked questions
How many kelvin are in a degree Fahrenheit?
One degree Fahrenheit equals 255.928 kelvin. Because these are temperature scales with different zero points, this is not a ratio you can multiply by — you have to apply the full formula for any other value.
How do I convert kelvin back to fahrenheit?
Reverse the formula: undo the addition first, then the multiplication. One kelvin works out as -457.87 fahrenheit. Our Kelvin to Fahrenheit page does it for you.
Is this conversion exact?
Yes. The Celsius, Fahrenheit and Kelvin scales are defined in terms of each other exactly, so the conversion carries no rounding error beyond what we display.
Where is each of these units used?
Fahrenheit: the everyday scale in the United States, where water freezes at 32° and boils at 212°. Kelvin: the SI temperature unit. It starts at absolute zero, so it never goes negative and takes no degree symbol.
Sources
- NIST Special Publication 811 — Guide for the Use of the International System of Units