Enter a temperature in Celsius, Fahrenheit or Kelvin and see it in the other two scales straight away — for recipes, weather forecasts, travel or science homework.
Formula
°F = °C × 9/5 + 32 · °C = (°F − 32) × 5/9 · K = °C + 273.15
Celsius and Kelvin use the same size of degree; Fahrenheit degrees are 5/9 the size and the scale is offset by 32.
Reference points
Water freezes at 0 °C (32 °F, 273.15 K) and boils at 100 °C (212 °F, 373.15 K) at sea level. Normal body temperature is about 37 °C (98.6 °F). −40 is the same in Celsius and Fahrenheit.
Frequently asked questions
How do I convert Celsius to Fahrenheit in my head?
Double the Celsius value and add 30 for a rough answer. 20 °C → 70 °F (exact: 68 °F).
Can Kelvin be negative?
No. 0 K is absolute zero, the lowest possible temperature, so Kelvin values are never negative.
Last updated · Calculations checked by automated tests· Editorial policy