Convert Fahrenheit to Kelvin Instantly
Use this Fahrenheit to Kelvin converter to change temperatures from degrees Fahrenheit (°F) into kelvins (K) in seconds. Enter any valid Fahrenheit temperature at or above absolute zero to get Kelvin, Celsius and Rankine equivalents, or switch to the reverse calculator when your starting value is already in kelvins.
Convert °F to K, reverse Kelvin to Fahrenheit, view Celsius alongside Kelvin, or convert a temperature across Fahrenheit, Celsius, Kelvin and Rankine.
Enter Fahrenheit to calculate Kelvin plus Celsius and Rankine equivalents.
Minimum physically meaningful value: −459.67°F.
Convert kelvins back to degrees Fahrenheit using the reverse formula.
Kelvin cannot be below 0 K.
Enter one Fahrenheit temperature and compare its Celsius and Kelvin equivalents side by side.
Choose a starting temperature unit and convert it to Fahrenheit, Celsius, Kelvin and Rankine.
Enter a Fahrenheit value and receive Kelvin immediately without rearranging the formula by hand.
Switch directions when laboratory, engineering or science data is supplied in kelvins.
The calculators reject values below the physical lower limit of the absolute temperature scale.
Calculator cards, tables, figures and FAQs adapt to smaller screens for quick field use.
Converting Fahrenheit to Kelvin requires both an offset adjustment and a change in scale size. Fahrenheit and Kelvin do not share the same zero point, and a Fahrenheit degree is smaller than a kelvin interval. For that reason, you cannot convert °F to K by multiplying with one constant factor alone.
The standard method is to first convert Fahrenheit to Celsius, then shift the Celsius zero point to the Kelvin scale. Subtract 32 from the Fahrenheit temperature, multiply by 5/9, and then add 273.15.
Use this equation for any physically meaningful Fahrenheit temperature.
Start with 68°F. Subtract 32 to get 36. Multiply 36 by 5/9 to get 20°C. Add 273.15, producing 293.15 K. Therefore, 68°F = 293.15 K.
Water's commonly used freezing reference is 32°F. Subtracting 32 gives 0; multiplying by 5/9 still gives 0; adding 273.15 yields 273.15 K.
If you want to calculate the conversion manually, use this five-step process. Keeping the operations in order is important because changing the sequence produces the wrong answer.
Write the Fahrenheit temperature you want to convert.
Remove the Fahrenheit offset from the temperature.
Begin changing Fahrenheit intervals to Celsius-sized intervals.
This completes the Fahrenheit-to-Celsius scale conversion.
Shift from Celsius to the absolute Kelvin scale.
The table below lists common Fahrenheit temperatures and their Kelvin equivalents. Values are rounded where necessary for readability.
| Fahrenheit (°F) | Kelvin (K) | Celsius (°C) | Typical Reference |
|---|---|---|---|
| −459.67 | 0 | −273.15 | Absolute zero |
| −40 | 233.15 | −40 | Same numeric °F and °C |
| 0 | 255.372 | −17.778 | Cold weather reference |
| 32 | 273.15 | 0 | Water freezing point reference |
| 50 | 283.15 | 10 | Cool air |
| 68 | 293.15 | 20 | Comfortable room reference |
| 77 | 298.15 | 25 | Warm room reference |
| 98.6 | 310.15 | 37 | Common body-temperature reference |
| 100 | 310.928 | 37.778 | Rounded everyday reference |
| 212 | 373.15 | 100 | Water boiling point reference at standard pressure |
| 500 | 533.15 | 260 | High-temperature reference |
Remembering a few exact or familiar points makes Fahrenheit and Kelvin easier to compare mentally.
The interval size is also useful: a change of 1 kelvin equals a change of 1 degree Celsius, while a change of 1°F equals 5/9 of a kelvin. This matters when converting temperature differences as opposed to absolute temperature readings.
Many unit conversions, such as inches to centimeters or kilograms to grams, use a direct multiplication factor because both scales begin at the same conceptual zero. Temperature is different. Fahrenheit and Kelvin use different zero points and different interval sizes, so the conversion needs both scaling and offsetting.
Kelvin begins at absolute zero, the theoretical lower limit of thermodynamic temperature. Fahrenheit's zero is defined differently, and the Fahrenheit scale uses 180 intervals between water's freezing and boiling references, while Celsius and Kelvin use 100 equal intervals across the same span. That is why the fraction 5/9 appears in the Fahrenheit to Kelvin equation.
For a related conversion, you can use our Fahrenheit to Celsius converter. If your starting point is Kelvin, see the Kelvin to Fahrenheit converter or Kelvin to Celsius converter.
Fahrenheit is widely used for everyday weather, indoor temperatures, cooking and household applications in the United States. It uses a degree symbol and has 180 degrees between the common freezing and boiling reference points of water.
A Fahrenheit interval is smaller than a Celsius degree or kelvin. Temperature changes therefore need a 5/9 or 9/5 scaling relationship when moving between the systems.
Kelvin is the SI base unit of thermodynamic temperature and is common in science, engineering, physics, chemistry and technical calculations. The scale begins at absolute zero.
The kelvin has the same interval size as the degree Celsius, so converting Celsius to Kelvin only requires adding 273.15. Unlike Celsius and Fahrenheit, Kelvin is written without the degree symbol.
Kelvin is especially important where equations depend on absolute temperature. Gas-law calculations, thermodynamics, heat transfer, black-body radiation, materials testing and many chemical relationships can require absolute temperature rather than a relative scale. Using Fahrenheit directly in such equations can create serious errors unless the equation is specifically written for Fahrenheit or Rankine.
For example, ratios such as T₂/T₁ must use an absolute temperature scale. Converting a Fahrenheit reading to Kelvin first provides a suitable SI absolute temperature value. In US customary engineering work, Rankine can serve a similar absolute-scale role because Rankine uses Fahrenheit-sized intervals but starts at absolute zero.
For authoritative SI information, see the BIPM SI measurement units guidance and the NIST SI temperature guidance.
Multiplying Fahrenheit directly by 5/9 and adding 273.15 is incorrect. The subtraction must happen first.
The 9/5 factor belongs in the reverse Celsius-to-Fahrenheit direction. For Fahrenheit to Kelvin, use 5/9 after subtracting 32.
The correct symbol is K. The degree sign is not used with kelvin.
A Fahrenheit value below −459.67°F converts to a negative Kelvin value and is not physically meaningful on the thermodynamic temperature scale. This calculator blocks such entries.
For technical work, keep extra decimal places during the calculation and round only the final value to the precision your application requires.
If you are working across several temperature systems, these related converters can reduce manual calculation:
When you publish several related converter pages, natural internal linking helps visitors move directly to the direction or unit system they actually need rather than repeating manual calculations.
A simple visual showing how familiar Fahrenheit temperatures align with the absolute Kelvin scale.
Quick answers about the °F to K formula, Kelvin notation, absolute zero and common conversions.