Fahrenheit to Kelvin
Type a temperature in °F to get kelvins. The converter uses K = (°F − 32) × 5/9 + 273.15, so 32 °F is 273.15 K.
Formula: K = (°F − 32) × 5/9 + 273.15
In short
- 1Subtract 32, multiply by 5/9, then add 273.15.
- 232 °F, the freezing point of water, is 273.15 K.
- 30 K, absolute zero, sits at −459.67 °F.
- 4A step of 1 °F is 5/9 of a kelvin.
Fahrenheit to kelvin table
| Degrees Fahrenheit (°F) | Kelvins (K) |
|---|---|
| -40 | 233.15 |
| 0 | 255.3722 |
| 32 | 273.15 |
| 40 | 277.5944 |
| 50 | 283.15 |
| 60 | 288.7056 |
| 68 | 293.15 |
| 70 | 294.2611 |
| Degrees Fahrenheit (°F) | Kelvins (K) |
|---|---|
| 77 | 298.15 |
| 86 | 303.15 |
| 98.6 | 310.15 |
| 100 | 310.9278 |
| 150 | 338.7056 |
| 212 | 373.15 |
| 350 | 449.8167 |
A worked example
Take a 68 °F room. Subtract 32 to get 36, multiply by 5/9 to get 20, which is the temperature in Celsius, then add 273.15 for 293.15 K. Going through Celsius is the safest route, because each step is easy to check.
The one-line version is K = (°F + 459.67) × 5/9, and it gives the same answer: (68 + 459.67) × 5/9 = 293.15.
The table above follows the same route, so any row can be checked by hand, and the converter flags inputs below −459.67 °F, which would be colder than absolute zero.
- Rankine
- Also called °R · °Ra
- An absolute scale with Fahrenheit-sized degrees. 0 °R is absolute zero and 491.67 °R is the freezing point of water. Some US engineering tables still use it; dividing by 1.8 turns rankine into kelvin.
Where you need this
US engineering and HVAC work often starts in Fahrenheit, while thermodynamics formulas expect absolute temperatures. Gas law problems, for example, give wrong answers if you plug in °F directly. NIST gives the exact conversion in SP 811.
For everyday temperatures, celsius to fahrenheit is usually all you need, and kelvin to celsius covers lab values.
US HVAC specifications often give temperature differences in °F, for example a 20 °F rise across a heat exchanger. A difference converts with the 5/9 factor alone and no offset, so a 20 °F rise is 11.1 K. Adding 273.15 to a difference is a common mistake that gives nonsense results.
Fahrenheit to kelvin questions
How many kelvins is 0 °F?
0 °F is 255.37 K, which is −17.78 °C.
What is 212 °F in kelvin?
212 °F, the boiling point of water at sea level, is 373.15 K.
Where does absolute zero sit on the Fahrenheit scale?
−459.67 °F, the same point as 0 K.
Is there a one-step formula for °F to K?
Yes: K = (°F + 459.67) × 5/9. It gives the same result as going through Celsius.