Why 273.15 for Kelvin?

Absolute zero is defined as 0 K, which equals −273.15 °C.

When did the US adopt Fahrenheit?

The US still uses Fahrenheit widely; most of the world uses Celsius.

Fahrenheit's absolute scale: R = F + 459.67.

Not physically possible — the calculator still shows the math.

Convert any temperature between the three most common scales instantly.

Reviewed & updated: January 1970

ValueFrom unit

Where it sits (°C)

−40 °C freeze100 °C boil

°C

100.00

°F

212.00

373.15

Celsius100.0000 °C

Fahrenheit212.0000 °F

Kelvin373.1500 K

Results are estimates for general information only and are not professional financial, medical, tax, or legal advice. Read the full disclaimer.

F = C·9/5 + 32. K = C + 273.15.

Example

100 °C = 212 °F = 373.15 K.

Why 273.15 for Kelvin?: Absolute zero is defined as 0 K, which equals −273.15 °C.
When did the US adopt Fahrenheit?: The US still uses Fahrenheit widely; most of the world uses Celsius.
Rankine?: Fahrenheit's absolute scale: R = F + 459.67.
Below absolute zero?: Not physically possible — the calculator still shows the math.