Temperature Converter
Celsius, Fahrenheit & Kelvin
Celsius
°C
Fahrenheit
°F
Kelvin
K
Common reference points
How it works
Type a value in any field and the other two update instantly.
The three scales
Celsius was defined in 1742 by Anders Celsius with 0° at water's freezing point and 100° at its boiling point (at standard atmospheric pressure). It is the everyday standard in most of the world.
Fahrenheit predates Celsius, proposed by Daniel Gabriel Fahrenheit in 1724. He anchored 0° to a freezing brine mixture and 96° to human body temperature - which is why the scale feels arbitrary. Water freezes at 32°F and boils at 212°F.
Kelvin is the SI thermodynamic scale, introduced by Lord Kelvin in 1848. It uses the same degree size as Celsius but starts at absolute zero (-273.15 °C), the theoretical point where all molecular motion stops. There are no negative Kelvin values.
Fahrenheit predates Celsius, proposed by Daniel Gabriel Fahrenheit in 1724. He anchored 0° to a freezing brine mixture and 96° to human body temperature - which is why the scale feels arbitrary. Water freezes at 32°F and boils at 212°F.
Kelvin is the SI thermodynamic scale, introduced by Lord Kelvin in 1848. It uses the same degree size as Celsius but starts at absolute zero (-273.15 °C), the theoretical point where all molecular motion stops. There are no negative Kelvin values.
Conversion formulas
°F = (°C × 9/5) + 32
°C = (°F - 32) × 5/9
K = °C + 273.15
°C = K - 273.15
Reference points
- Absolute zero: -273.15 °C = -459.67 °F = 0 K
- Water freezes: 0 °C = 32 °F = 273.15 K
- Body temperature: 37 °C = 98.6 °F = 310.15 K
- Water boils: 100 °C = 212 °F = 373.15 K