Fahrenheit to Kelvin
Convert Fahrenheit to Kelvin instantly. Free temperature converter, no signup.
How to use this tool
- Enter degrees fahrenheit in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your degrees kelvin and the full breakdown beneath it.
Convert Fahrenheit to Kelvin instantly. Free temperature converter, no signup.
Formula
Kelvin = (Fahrenheit − 32) × 5/9 + 273.15
K = (°F − 32) × 5/9 + 273.15
The first step converts Fahrenheit to Celsius; the second step shifts Celsius to the Kelvin absolute scale.
How it works
Subtract 32 from the Fahrenheit value to remove the Fahrenheit offset, then multiply by 5/9 to rescale degrees to the Celsius/Kelvin degree size, then add 273.15 to shift the origin to absolute zero. The two-stage process is needed because Fahrenheit and Kelvin differ in both their zero point and their degree size.
Common mistake: People often forget to subtract 32 before multiplying — applying the 5/9 factor to the raw Fahrenheit value produces a result that is too low and incorrect. The subtraction must come first.
Worked example
Convert 32 °F (the freezing point of water) to Kelvin
- Start with 32 °F (the input value).
- Subtract 32: 32 − 32 = 0.
- Multiply by 5/9: 0 × 5/9 = 0.
- Add 273.15: 0 + 273.15 = 273.15 K
273.15 K — identical to the Kelvin equivalent of 0 °C, the freezing point of water.
Common mistakes to avoid
- Forgetting the two-step process and applying only the +273.15 shift without first converting to Celsius, giving a result that is 32 x 5/9 = 17.78 K too high.
- Applying the steps in the wrong order — adding 273.15 before converting Fahrenheit to Celsius.
- Using 273 instead of 273.15 in the final step, introducing a 0.15 K offset in scientific calculations.
Key terms
- Fahrenheit (°F)
- A temperature scale used primarily in the United States where water freezes at 32 °F and boils at 212 °F.
- Kelvin (K)
- The SI absolute temperature scale starting at 0 K (absolute zero); degrees are the same size as Celsius degrees.
- Degree size
- The magnitude of one degree on a temperature scale. Celsius and Kelvin share the same degree size; Fahrenheit degrees are 5/9 as large.
- Two-stage conversion
- A conversion requiring two operations — here, first mapping Fahrenheit to Celsius, then shifting Celsius to Kelvin.
Frequently asked questions
- What is 32 F in Kelvin?
- (32 - 32) x 5/9 + 273.15 = 273.15 K, the freezing point of water.
- What is 212 F in Kelvin?
- (212 - 32) x 5/9 + 273.15 = 100 + 273.15 = 373.15 K, the boiling point of water at sea level.
- Why convert through Celsius instead of directly?
- There is no single-step Fahrenheit-to-Kelvin formula in common use. The two-step path (F to C to K) is clearer and less error-prone.