Convert Fahrenheit to Kelvin

About converting Fahrenheit to Kelvin

Fahrenheit (°F) and Kelvin (K) are different temperature scales, so they convert with a formula rather than a simple ratio: K = (°F − 32) × 5/9 + 273.15. That is why 100 Fahrenheit is 310.9278 Kelvin but 1 Fahrenheit is 255.9278 Kelvin — the scales have different zero points, so you cannot just multiply.

What is a Fahrenheit?

Daniel Gabriel Fahrenheit published his scale in 1724, building it around fixed points he could actually reproduce in a workshop: zero was set by a freezing brine of ice, water and salt — about the coldest he could reliably make — and the upper anchor sat near human body temperature. Officially it survives today essentially only in the United States and a handful of territories. Its one genuine advantage is granularity: its degrees are smaller, so ordinary weather spreads across a wider span of whole numbers, and 0 to 100 maps roughly onto the range of human comfort.

What is a Kelvin?

Unlike the other temperature scales, the kelvin starts at the true bottom of the range: absolute zero, the point at which thermal motion is minimal. Because nothing can be colder there are no negative kelvins, and by convention no degree symbol either — it is "300 kelvin", never "300 degrees Kelvin". It is the SI base unit of thermodynamic temperature, named for William Thomson, Lord Kelvin, who took his title from the river running through Glasgow, and it was redefined in 2019 in terms of the Boltzmann constant. Most people meet it unknowingly when buying light bulbs, where colour temperature is quoted in kelvin.

To put both in perspective: water freezes at 32 degrees Fahrenheit, while room temperature is about 293 kelvin.

The converter above updates as you type, and the table lists common values for quick reference. Need the opposite direction? Use the Kelvin to Fahrenheit converter, or browse all Temperature converters.