Temperature Converter
Convert between Celsius, Fahrenheit and Kelvin — with the formula worked out step by step.
About this tool
Enter a temperature and pick the scale you have and the scale you want. You get the converted value, the formula with your numbers filled in, and the same temperature in °C, °F and K at once. Values below absolute zero are flagged.
Frequently asked questions
Multiply by 9/5 (1.8) and add 32: °F = °C × 9/5 + 32. For example 20 °C × 1.8 + 32 = 68 °F, and 100 °C (boiling water at sea level) is 212 °F.
Subtract 32 and multiply by 5/9: °C = (°F − 32) × 5/9. For example (98.6 °F − 32) × 5/9 = 37 °C, and 32 °F is 0 °C, the freezing point of water.
Kelvin is the SI unit of temperature. It starts at absolute zero, so K = °C + 273.15 and there are no negative values. A one-degree step is the same size in kelvin and Celsius: 20 °C is 293.15 K.
At −40. Solving x = x × 9/5 + 32 gives x = −40, so −40 °C is exactly −40 °F. Absolute zero is −273.15 °C = −459.67 °F = 0 K, the lowest possible temperature.
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