Temperature Converter – Celsius, Fahrenheit & Kelvin

Convert Celsius, Fahrenheit and Kelvin

Temperature conversions need both a multiplier and an offset because the scales start at different zero points. Enter a value on either side, choose the source and target scales, and the converter updates the other value. This is useful for weather, cooking, travel, school and science where a result needs to be checked against the right scale.

Common temperature conversion formulas

To convert Celsius to Fahrenheit, multiply by 9/5 and add 32: °F = (°C × 9/5) + 32. To convert Fahrenheit to Celsius, subtract 32 then multiply by 5/9: °C = (°F − 32) × 5/9. Celsius and Kelvin have the same-sized intervals but different starting points: K = °C + 273.15 and °C = K − 273.15.

Useful reference temperatures

Water freezes at 0 °C, 32 °F and 273.15 K. At standard atmospheric pressure, water boils near 100 °C, 212 °F and 373.15 K. The Celsius and Fahrenheit scales meet at −40: −40 °C equals −40 °F. These references help spot an input or unit-selection mistake before you use a converted result.

Kelvin is not written with a degree sign

Kelvin is an absolute temperature scale, so the unit is written K rather than °K. Absolute zero is 0 K, which is −273.15 °C and −459.67 °F. A value below 0 K can be transformed mathematically by a formula but does not represent an ordinary physical temperature, so check which scale your source uses.

Temperature differences are different from temperatures

A change of 1 K is the same size as a change of 1 °C, but a change of 1 °F is smaller. Do not add or multiply Celsius or Fahrenheit readings as though their zero point were absolute. For other everyday conversions, use the related length converter or volume converter.