Convert any temperature between Celsius, Fahrenheit and Kelvin at once — with the formulas shown and absolute zero respected.
How the three scales relate
Celsius and Fahrenheit are offset and scaled versions of each other; Kelvin is Celsius shifted so that zero sits at absolute zero, the coldest anything can be. Enter a value in any scale and this converter shows all three simultaneously — and flags anything below absolute zero as impossible rather than printing a meaningless number.
How to use it
- Enter the temperature value.
- Choose which scale it’s in.
- Read the same temperature in °C, °F and K.
The formulas
A worked example
100°C — boiling water at sea level — is 212°F and 373.15 K. The everyday anchors are worth memorising: 0°C/32°F freezing, 37°C/98.6°F body temperature, and −40 the curiosity where both scales read the same number. For a rough °C→°F in your head: double it and add 30 — close enough for weather, and this converter for everything that has to be exact.