K = (°F − 32) × 5 ÷ 9 + 273.15
Temperature scales require both a scale and an offset.Conversion lab / temperature
Fahrenheit to Kelvin Converter
Convert degrees Fahrenheit to kelvins with a tested affine conversion.
Fahrenheit to Kelvin Converter: Convert a Fahrenheit measurement directly into the absolute kelvin scale for a calculation or technical comparison. This combines the Fahrenheit-to-Celsius change with the Celsius-to-kelvin offset. You can check the intermediate Celsius value without rounding it before the final step. Runs 100% locally in your browser with zero server file uploads.
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Kkelvins
-459.67 °F-2.842171e-14 K
-40 °F233.15 K
32 °F273.15 K
68 °F293.15 K
212 °F373.15 K
Degrees Fahrenheit to kelvins conversion table
| degrees Fahrenheit (°F) | kelvins (K) |
|---|---|
| -459.67 °F | -2.842171e-14 K |
| -450 °F | 5.372222 K |
| -400 °F | 33.15 K |
| -350 °F | 60.92778 K |
| -300 °F | 88.70556 K |
| -250 °F | 116.4833 K |
| -200 °F | 144.2611 K |
| -150 °F | 172.0389 K |
| -100 °F | 199.8167 K |
| -50 °F | 227.5944 K |
| degrees Fahrenheit (°F) | kelvins (K) |
|---|---|
| -40 °F | 233.15 K |
| 0 °F | 255.3722 K |
| 32 °F | 273.15 K |
| 50 °F | 283.15 K |
| 68 °F | 293.15 K |
| 100 °F | 310.9278 K |
| 150 °F | 338.7056 K |
| 200 °F | 366.4833 K |
| 212 °F | 373.15 K |
Rounded to seven significant digits; the converter above uses the full factor.
Two steps without premature rounding
Let F be the Fahrenheit reading and T the temperature in kelvin. T = (F − 32) × 5/9 + 273.15. For F = 68, calculate 68 − 32 = 36, then 36 × 5/9 = 20, then 20 + 273.15 = 293.15 K. This affine formula includes both a scale change and an offset; it cannot be replaced by multiplying F by a universal ratio.
The NIST exact conversions (https://www.nist.gov/pml/owm/si-units-temperature) provide the two relationships used here. Kelvin values use capital K with no degree sign.
Checking a cold reference point
At −40 °F, the intermediate Celsius value is (−40 − 32) × 5/9 = −40 °C. The coincidence arises from setting C = F in F = 9C/5 + 32 and solving for −40. It is a convenient cross-check for arithmetic, but does not turn the scales into proportional ones. Convert readings first if comparing absolute-temperature ratios in a physics problem.
How to use it
- Enter the temperature in degrees Fahrenheit.
- Read the converted kelvins value as it updates.
- Use the common values or open the reverse conversion to cross-check.
Privacy & limitations
Your value never leaves this browser. JavaScript floating-point arithmetic can round the last displayed digit; this general utility is not a substitute for calibrated or regulated measurement systems.
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Frequently asked questions
Can I get kelvin by adding 273.15 to Fahrenheit?
That addition works only after the reading is in Celsius. Start by subtracting 32 from Fahrenheit and multiplying by 5/9. At 68 °F the intermediate value is 20 °C, so adding 273.15 gives 293.15 K, not 341.15 K.
What Fahrenheit input reaches absolute zero?
−459.67 °F converts to 0 K. The input field rejects lower readings. A Fahrenheit number below zero can still be above absolute zero: −40 °F converts to 233.15 K.
Does an 18 °F warming become 283.15 K?
No. An 18 °F change is a 10 K change, found by multiplying 18 by 5/9. Offsets cancel when subtracting two temperatures. For the same reason, a 10 °C difference = 18 °F, even though an actual 10 °C reading is 50 °F.
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