UnitSnapTemperature converter
Temperature measures how hot or cold something is, reflecting the average kinetic energy of its particles. The SI base unit is the kelvin (K), an absolute scale that starts at absolute zero. Since 2019, the kelvin has been defined by fixing the value of the Boltzmann constant. Kelvin values are written without a degree sign.
Convert between 5 temperature units. Pick any two units below; results update as you type.
Popular temperature conversions
About temperature units
Celsius is used for weather and cooking in nearly every country, while the United States uses Fahrenheit for everyday temperatures. Celsius is offset from kelvin by exactly 273.15, so 0 °C equals 273.15 K. Fahrenheit uses a smaller degree: °F = °C × 9/5 + 32. The two scales read the same at −40.
Rankine is an absolute scale with Fahrenheit-sized degrees, used in some US engineering work. Réaumur, once common in parts of Europe, divides the interval between the freezing and boiling points of water into 80 degrees instead of 100.
Tips
- Temperature conversions involve an offset, not just a multiplier, so doubling a Celsius value does not double the Fahrenheit value.
- A temperature difference converts without the offset: a change of 1 °C equals a change of 1.8 °F and exactly 1 K.
- Use kelvin or Rankine for gas-law and other physics calculations that require an absolute temperature.
All temperature units
| Unit | Symbol |
|---|---|
| Celsius | °C |
| Fahrenheit | °F |
| Kelvin | K |
| Rankine | °R |
| Réaumur | °Ré |
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Factors: NIST SP 811 · SI Brochure · NIST Handbook 44 — Updated