Degrees Fahrenheit to kelvin Converter

How many kelvin are in a degree Fahrenheit?

Temperature is the one conversion on this site that is not a simple multiplication. degree Fahrenheit and kelvin have different zero points as well as different degree sizes, so you must apply an offset as well as a scale factor. The formula is K = (°F − 32) × 5/9 + 273.15.

This is why "twice as many degrees" never means "twice as hot", and why you cannot convert a temperature difference the same way you convert a temperature. A rise of 10 °C is a rise of 18 °F, not 50 °F.

The reference table under the converter lists the values people look up most often, so for a common figure you can read the answer off directly rather than typing anything.

Worked examples

Three worked examples, using K = (°F − 32) × 5/9 + 273.15:

32 °F converts to 273.15 K. 72 °F converts to 295.37 K. 98.6 °F converts to 310.15 K.

Notice that the gaps between the converted values are not proportional to the gaps between the originals in the way they would be for a simple multiplication — that is the offset at work, and it is why temperature needs its own formula rather than a factor.

Doing this conversion in your head

Kelvin conversions are the easiest of the three, because the degree size is identical to Celsius — only the zero point moves. Add 273.15 to go from Celsius to kelvin, subtract it to come back, and round to 273 for anything that is not laboratory work.

Because the scales share a degree size, a temperature *change* is numerically identical in Celsius and kelvin. A rise of 5 °C is a rise of 5 K.

When you need to convert degrees Fahrenheit to kelvin

There are a handful of recurring contexts where a degree Fahrenheit figure has to be restated in kelvin.

On the source side, Fahrenheit is the weather forecast, oven dial and thermostat setting in the United States. On the target side, kelvin appears in physics, colour temperature for lighting and photography, and scientific data. The conversion is essentially a translation between those two worlds — most often because a figure produced in one context has to be understood, submitted or acted on in the other.

Precision matters unevenly here. An oven is forgiving to within about five degrees; a medical threshold or a materials specification is not.

Whatever the reason, the arithmetic runs in your browser. Nothing you type is transmitted, logged or stored, and the converter keeps working if you go offline after the page has loaded.

What a degree Fahrenheit and a kelvin actually are

The degree Fahrenheit (°F). Daniel Fahrenheit's 1724 scale, now used officially only in the United States and a few territories.

The kelvin (K). The SI base unit of temperature, starting at absolute zero with no negative values.

Since degrees Fahrenheit and kelvin both quantify temperature against a common defined standard, nothing is lost in translating between them. The only imprecision anywhere in this page is deliberate rounding for readability.

Common mistakes when converting degrees Fahrenheit to kelvin

The classic error is converting a difference as though it were a value. Adding the 32 offset is correct for a temperature; it is wrong for a change in temperature. If a forecast says it will be 10 °C warmer tomorrow, that is 18 °F warmer, not 50 °F warmer.

A second trap is kelvin notation: it is written "300 K", never "300 °K" and never "degrees kelvin". Kelvin is an absolute scale with no degree symbol, and it never goes negative — −273.15 °C is absolute zero, the floor of the scale.

For a batch of figures, set the units once and work down the list rather than converting via a third unit — each intermediate step introduces its own rounding.