Temperature reference
Celsius Temperature Scale (°C)
Celsius, historically called centigrade, is a temperature scale on which water freezes at 0°C and boils at 100°C at standard atmospheric pressure.
What is Celsius?
Celsius, historically called centigrade, is a temperature scale on which water freezes at 0°C and boils at 100°C at standard atmospheric pressure.
Swedish astronomer Anders Celsius proposed the scale in 1742. Its direction was later reversed into the familiar form, and the degree Celsius is now defined using the same interval size as the kelvin.
Celsius is the principal everyday temperature scale in most countries and is widely used in science, medicine, weather reporting, cooking, and engineering. Kelvin remains the SI base unit for thermodynamic temperature.
Celsius conversion formula
Convert Celsius to Fahrenheit with:
°F = (°C × 9/5) + 32
Common Celsius reference points
| Celsius | Fahrenheit | Reference |
|---|---|---|
| −40°C | −40°F | Both scales are equal |
| 0°C | 32°F | Water freezing point |
| 20°C | 68°F | Room-temperature reference |
| 37°C | 98.6°F | Body-temperature reference |
| 100°C | 212°F | Water boiling point |
Standards and review
Reviewed by the All Unit Conversions Editorial Team. Updated .
Reference sources: BIPM SI Brochure and NIST SP 811.