To convert Fahrenheit to Kelvin: subtract 32, multiply by 5/9, then add 273.15. Formula: K = (°F − 32) × 5/9 + 273.15. Key values: 32°F = 273.15 K (water freezes), 212°F = 373.15 K (water boils), −459.67°F = 0 K (absolute zero).
- Formula: K = (°F − 32) × 5/9 + 273.15 - convert to Celsius first, then add 273.15.
- 32°F = 273.15 K - water freezes.
- 212°F = 373.15 K - water boils at sea level.
- −459.67°F = 0 K - absolute zero (the minimum possible temperature).
How to Use This Converter
Type any Fahrenheit value in the °F field and the Kelvin result appears instantly. You can also type in the K field to convert back to Fahrenheit - it works in both directions without pressing a button.
How Do You Convert Fahrenheit to Kelvin?
The conversion requires two adjustments: first convert Fahrenheit to Celsius (subtract 32, multiply by 5/9), then convert Celsius to Kelvin (add 273.15). These two steps are combined into one formula:
$$K = (°F - 32) \times \frac{5}{9} + 273.15$$
Worked step-by-step for 98.6°F: (98.6 − 32) = 66.6, × 5/9 = 37, + 273.15 = 310.15 K.
Other examples: 32°F = 273.15 K. 72°F = 295.37 K. 212°F = 373.15 K. −40°F = 233.15 K.
How Do You Convert Kelvin to Fahrenheit?
Subtract 273.15, multiply by 9/5, then add 32. See the dedicated Kelvin to Fahrenheit converter for a Kelvin-first reference table.
$$°F = (K - 273.15) \times \frac{9}{5} + 32$$
Worked examples: 273.15 K = 32°F. 298.15 K = 68.3°F. 373.15 K = 212°F.
Fahrenheit to Kelvin Reference Table
Common temperatures converted using K = (°F − 32) × 5/9 + 273.15:
| Fahrenheit (°F) | Kelvin (K) | Context |
|---|---|---|
| −459.67°F | 0 K | Absolute zero |
| −40°F | 233.15 K | °C = °F crossover point |
| 0°F | 255.37 K | Fahrenheit zero |
| 32°F | 273.15 K | Water freezes |
| 68°F | 293.15 K | Room temperature |
| 72°F | 295.37 K | Typical US indoor thermostat |
| 98.6°F | 310.15 K | Normal body temperature |
| 100.4°F | 311.15 K | Fever threshold (adults) |
| 212°F | 373.15 K | Water boils at sea level |
| 350°F | 449.82 K | Moderate oven (US baking) |
When Do You Need to Convert Fahrenheit to Kelvin?
This conversion is needed when working with US-based temperature data in scientific contexts that require absolute temperatures:
- Thermodynamics - US engineering problems often give temperatures in °F, but gas laws and efficiency equations require Kelvin.
- Chemical engineering - US-originated process temperatures in °F must be converted to K for thermodynamic property lookups.
- Physics courses - textbooks that use Fahrenheit examples (common in older US editions) require converting to Kelvin for ideal gas and blackbody radiation problems.
- HVAC engineering - US HVAC uses °F; international standards and heat transfer equations use Kelvin.
Frequently Asked Questions
How do you convert Fahrenheit to Kelvin?
Subtract 32, multiply by 5/9, then add 273.15. The intermediate result after the first two steps is the Celsius equivalent. Formula: K = (°F − 32) × 5/9 + 273.15. Example: 212°F → (212 − 32) × 5/9 + 273.15 = 100 + 273.15 = 373.15 K.
What is 32°F in Kelvin?
32°F = 273.15 K. This is the freezing point of water. Calculation: (32 − 32) × 5/9 + 273.15 = 0 + 273.15 = 273.15 K.
What is 212°F in Kelvin?
212°F = 373.15 K. This is the boiling point of water at sea level. Calculation: (212 − 32) × 5/9 + 273.15 = 180 × 5/9 + 273.15 = 100 + 273.15 = 373.15 K.
What is absolute zero in Fahrenheit?
Absolute zero is −459.67°F (= 0 K = −273.15°C). It is the lowest possible temperature. Calculation using the reverse formula: (0 − 273.15) × 9/5 + 32 = −491.67 + 32 = −459.67°F.