Kelvin is the SI absolute temperature scale.
Kelvins to Fahrenheit Converter — K to F
Convert Kelvin (K) to Fahrenheit (F) using the exact temperature formula. See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Kelvins to Fahrenheit converter
Converter
Temperature Converter
Convert Celsius, Fahrenheit, Kelvin, Rankine, Delisle, Newton, Reaumur, and Romer.
Context values
Some unit families need one extra value for a physically accurate result.
Fahrenheit is a temperature scale with water freezing at 32 F and boiling at 212 F.
Convert the source temperature to Kelvin, then convert Kelvin to the target scale.
Temperature conversion uses Kelvin as the intermediate absolute scale.
Reserved above the conversion cards and below the converter.
About Converting Kelvins to Fahrenheit
Kelvin and Fahrenheit are the two everyday temperature scales, and converting between them matters for reading weather forecasts, following recipes, and understanding scientific data across regions. Kelvin is typically associated with standard scientific temperature unit worldwide, while Fahrenheit is typically associated with united States (primary everyday temperature scale).
Formula
Convert the source temperature to Kelvin, then convert Kelvin to the target scale.
Both scales are converted through Kelvin as a common absolute reference point.
Simple example
(0 − 32) × 5/9 = -459.67 °C
0 kelvins = -459.67 fahrenheit.
Real-world example
(0 − 32) × 5/9 = -459.67 °C
0 kelvins = -459.67 fahrenheit.
Conversion table
| Kelvin (K) | Fahrenheit (F) |
|---|---|
| -40 K | -531.67 F |
| -20 K | -495.67 F |
| 0 K | -459.67 F |
| 20 K | -423.67 F |
| 37 K | -393.07 F |
| 100 K | -279.67 F |
Reverse conversion: Fahrenheit to Kelvin
(-457.87 − 32) × 5/9 = 1 °C
-457.87 fahrenheit = 1 kelvin.
Convert the source temperature to Kelvin, then convert Kelvin to the target scale.
For a page dedicated to this direction, see Fahrenheit to Kelvin.
Kelvin vs. Fahrenheit
| Aspect | Kelvin | Fahrenheit |
|---|---|---|
| Family | SI base unit | Non-SI temperature scale |
| Typical use | Scientific and engineering temperature measurement (physics, chemistry) | Everyday weather reporting and thermostats in the US |
| Where it's used | Standard scientific temperature unit worldwide | United States (primary everyday temperature scale) |
Understanding the Kelvin
Kelvin (K) measures temperature. The kelvin is the SI base unit of thermodynamic temperature; 0 K (absolute zero) is the theoretical absence of thermal energy. It is classified as a SI base unit.
Where it's used: Standard scientific temperature unit worldwide
Uses of the Kelvin today
- Scientific and engineering temperature measurement (physics, chemistry)
- Color temperature specifications (lighting, displays)
- Cryogenics and low-temperature physics
History of the Kelvin
The kelvin scale was proposed by William Thomson (Lord Kelvin) in 1848, building on Sadi Carnot's thermodynamic work to define an absolute temperature scale independent of any particular substance's properties, with zero set at absolute zero.
Since 2019, the kelvin has been defined by fixing the Boltzmann constant at an exact value, tying it to a fundamental physical constant rather than the triple point of water used previously.
Historical origin. Kelvin was not the invention of a single named person; it developed through the process described above.
Understanding the Fahrenheit
Fahrenheit (F) measures temperature. Fahrenheit sets water's freezing point at 32 °F and boiling point at 212 °F at standard atmospheric pressure. It is classified as a Non-SI temperature scale.
Where it's used: United States (primary everyday temperature scale) A small number of other territories, e.g. the Bahamas, Belize, Cayman Islands, Liberia, Palau
Uses of the Fahrenheit today
- Everyday weather reporting and thermostats in the US
- Cooking temperatures in US recipes
- Some US industrial and HVAC contexts
History of the Fahrenheit
German physicist Daniel Gabriel Fahrenheit developed the scale around 1724, originally basing 0° on the coldest temperature he could reliably reproduce with an ice-salt mixture, and calibrating other points using human body temperature and the freezing point of water.
The modern Fahrenheit scale was later standardized so that water freezes at exactly 32 °F and boils at exactly 212 °F at one standard atmosphere, giving 180 degrees between the two reference points.
Historical origin. Fahrenheit was not the invention of a single named person; it developed through the process described above.
Kelvin — sources
- BIPM — The kelvin (SI base unit) — Current definition and history of the kelvin.
Fahrenheit — sources
- NIST — Temperature scales overview — History and modern definitions of Fahrenheit and Celsius.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many fahrenheit are in 1 kelvin?
1 kelvin equals -457.87 fahrenheit, using the offset temperature formula rather than an estimate.
How do I convert kelvin to fahrenheit?
Use the formula shown above: it involves both a multiplication and an addition/subtraction because the two scales don't share a common zero point.
How do I convert fahrenheit back to kelvin?
Use the reverse factor: 1 fahrenheit equals 255.9277778 kelvins. You can also use the swap control in the converter above to flip the direction instantly.
What is a kelvin?
Kelvin (K) measures temperature. The kelvin is the SI base unit of thermodynamic temperature; 0 K (absolute zero) is the theoretical absence of thermal energy. It is classified as a SI base unit.
What is a fahrenheit?
Fahrenheit (F) measures temperature. Fahrenheit sets water's freezing point at 32 °F and boiling point at 212 °F at standard atmospheric pressure. It is classified as a Non-SI temperature scale.
Is the Kelvin to Fahrenheit conversion exact?
Yes. Both scales are formally defined relative to the Kelvin scale, so the conversion formula is exact — the only rounding involved is in how many decimal places you choose to display.
Where is the kelvin still used today?
Standard scientific temperature unit worldwide