Temperature Converter

How this conversion works

Temperature scales differ in both the size of a degree and where zero sits, so they cannot be converted with a single multiplier. The converter first turns your value into degrees Celsius with that scale's own formula, then turns the Celsius value into the target scale.

A Fahrenheit degree is 5/9 the size of a Celsius degree, and water freezes at 32 °F instead of 0 °C. Kelvin uses Celsius-sized degrees but starts at absolute zero (−273.15 °C). Rankine does the same for Fahrenheit-sized degrees.

Formula: °F = °C × 9/5 + 32 · °C = (°F − 32) × 5/9 · K = °C + 273.15 · °R = K × 9/5

Where this conversion is used

• Following recipes and oven settings written for another country.
• Reading weather forecasts and body temperature in °C or °F.
• Science and engineering work that requires kelvins (absolute temperature).
• HVAC and thermostat settings when manuals use a different scale.

Worked example: 98.6 °F to Celsius and kelvins

1. Subtract 32: 98.6 − 32 = 66.6.
2. Multiply by 5/9: 66.6 × 5 ÷ 9 = 37 °C.
3. Add 273.15 for kelvins: 37 + 273.15 = 310.15 K.

Things to watch for

• Values below absolute zero (−273.15 °C, −459.67 °F, 0 K) are rejected because they cannot exist.
• −40 is the one temperature that reads the same in Celsius and Fahrenheit.
• A temperature difference converts without the offset: a rise of 10 °C is a rise of 18 °F, not 50 °F.

Precision and sources

Results are calculated from the definitions above and rounded to 12 significant digits; the converter shows up to eight decimal places and the tables four. Reference: NIST Special Publication 811, Guide for the Use of the International System of Units, Appendix B. Kelvin definition from the SI Brochure, 9th edition.

Frequently asked questions