Degrees Fahrenheit to kelvin converter

Read a quantity in °F, then express the same temperature in K. The units are defined below to avoid mixing similarly named standards.

Direct example

20 °F ≈ 266.483333333 K.

Formula and calculation

K = (°F × 0.555555555556 + -17.7777777778 − (-273.15)) ÷ 1

Substituting 20 °F gives approximately 266.483333333 K. Definitions use the constants above; arithmetic uses browser floating point and displays at most 12 significant digits. The rounded table is not an instrument calibration or certified measurement.

Which units does this page use?

degrees Fahrenheit: Fahrenheit temperature scale; 32 °F equals 0 °C.

kelvin: absolute thermodynamic scale; kelvin is written without a degree sign.

When this direction is useful

Start here when your source record uses °F for US temperature displays and recipe temperatures, but the receiving specification is expressed in K for scientific temperature specifications. Enter the original quantity rather than reusing a previously rounded result. If your source uses K, use the reverse converter instead.

Conversion table

Approximate displayed values, with the same definitions as the converter
degrees Fahrenheit (°F)	kelvin (K)
-40	233.15
0	255.372222222
20	266.483333333
37	275.927777778
100	310.927777778

Limits and interpretation

This converts a temperature reading, not a temperature difference. The scale offsets matter. Values below absolute zero are rejected. Use a decimal dot; grouping commas are not accepted. No external rates, live data or account are involved.

Frequently asked questions

Can I convert the other way?

Yes. Convert kelvin to degrees Fahrenheit with the inverse equation. Rounding a result before converting it back can introduce a small difference.

Are these the same as every similarly named unit?

No. Check the two definitions above. International length, avoirdupois mass, US customary liquid measures and temperature readings are explicitly distinguished; an ambiguous label on a source document must be resolved first.

Where do the conversion definitions come from?

They use SI and defined customary conversion relationships. See the NIST Guide for the Use of SI. Output formatting is this tool's display policy, not extra measurement accuracy.