Celsius to Fahrenheit formula
To convert Celsius to Fahrenheit: multiply by 9/5 and add 32.
Common conversions:
- 0°C = 32°F (freezing point of water)
- 20°C = 68°F (comfortable room temperature)
- 37°C = 98.6°F (normal body temperature)
- 100°C = 212°F (boiling point of water at sea level)
Fahrenheit to Celsius formula
To convert Fahrenheit to Celsius: subtract 32 and multiply by 5/9.
A quick mental shortcut: subtract 30 and halve the result. This gives an approximate answer fast — for example 70°F → (70 − 30) / 2 = 20°C (exact answer: 21.1°C).
Temperature reference table
| Description | °C | °F | K |
|---|---|---|---|
| Absolute zero | -273.15 | -459.67 | 0 |
| Liquid nitrogen (boiling) | -195.79 | -320.42 | 77.36 |
| Dry ice (sublimation) | -78.5 | -109.3 | 194.65 |
| Water freezing | 0 | 32 | 273.15 |
| Room temperature (typical) | 20–22 | 68–72 | 293–295 |
| Human body temperature | 37 | 98.6 | 310.15 |
| Water boiling (sea level) | 100 | 212 | 373.15 |
| Oven (moderate) | 180 | 356 | 453.15 |
| Surface of the Sun | 5,505 | 9,941 | 5,778 |
Celsius vs Fahrenheit — why two scales?
Celsius (°C) is used by most of the world and is part of the metric system. It sets 0° at water's freezing point and 100° at its boiling point — a logical scale for science and everyday use.
Fahrenheit (°F) is primarily used in the United States. It was defined in 1724 by Daniel Gabriel Fahrenheit, originally calibrated to the freezing point of a salt-water solution (0°F) and human body temperature (96°F in the original scale, later adjusted to 98.6°F).
Kelvin (K) is the SI unit of temperature used in science and physics. It starts at absolute zero — the point at which all molecular motion ceases — and uses the same degree size as Celsius. There is no negative temperature in Kelvin.