The Fahrenheit to Kelvin formula
To convert Fahrenheit to Kelvin, first convert to Celsius and add 273.15: K = (°F − 32) × 5/9 + 273.15. For example, 32 °F gives (32 − 32) × 5/9 + 273.15 = 273.15 K, where water freezes. For a Celsius step, see the Celsius to Kelvin calculator.
Worked example: 68 °F, a typical room temperature, gives (68 − 32) × 5/9 = 20 °C, and 20 + 273.15 = 293.15 K. Because one kelvin is exactly the same size as one Celsius degree, every answer ends in .15 whenever the Celsius value is a whole number.
How to convert °F to K
Enter a temperature in Fahrenheit. The calculator subtracts 32, multiplies by 5/9 to get Celsius, then adds 273.15 for Kelvin. Kelvin never goes negative because it starts at absolute zero, so very cold Fahrenheit values still give positive Kelvin.
The most common mistake is applying the steps out of order. Subtract 32 first, scale by 5/9, then add 273.15. Folding the 273.15 in early — (212 − 32 + 273.15) × 5/9 — returns 251.75 K instead of the correct 373.15 K for boiling water.
People working on this usually reach for the kelvin to celsius calculator too.
Fahrenheit to Kelvin reference table
| Fahrenheit | Kelvin |
|---|---|
| −459.67 °F | 0 K |
| 32 °F | 273.15 K |
| 98.6 °F | 310.15 K |
| 212 °F | 373.15 K |
The fixed points in the table are worth remembering: absolute zero at −459.67 °F, water freezing at 273.15 K and boiling at 373.15 K. Between those two there are exactly 100 kelvin against 180 Fahrenheit degrees, and that ratio is where the 5/9 factor comes from.
Pair this with the fahrenheit to celsius calculator when you need the fuller picture.
Frequently asked questions
- What is 32 Fahrenheit in Kelvin?
- 32 °F equals 273.15 K, the freezing point of water.
- What is the Fahrenheit to Kelvin formula?
- K = (°F − 32) × 5/9 + 273.15.
- What is absolute zero in Fahrenheit?
- 0 K equals −459.67 °F.
- Can I convert through Celsius first?
- Yes — convert °F to °C, then add 273.15. The Celsius to Kelvin calculator handles the second step.
- Should I write degrees Kelvin or just Kelvin?
- Just kelvin. It is an absolute scale, so temperatures are written 300 K, never 300 °K or 300 degrees Kelvin. The degree sign belongs to the relative scales, Fahrenheit and Celsius.