Temperature conversion between Celsius and Fahrenheit is something most people need at some point — whether checking a weather forecast from another country, adjusting an oven temperature, or understanding a medical reading.
The Formula: Celsius to Fahrenheit
Or equivalently: °F = (°C × 1.8) + 32
The Formula: Fahrenheit to Celsius
Or equivalently: °C = (°F − 32) ÷ 1.8
Key Reference Temperatures
| Celsius (°C) | Fahrenheit (°F) | What it means |
|---|---|---|
| −40°C | −40°F | The point where both scales are equal |
| 0°C | 32°F | Freezing point of water |
| 20°C | 68°F | Comfortable room temperature |
| 37°C | 98.6°F | Normal human body temperature |
| 100°C | 212°F | Boiling point of water |
Mental Math Shortcut
The exact formula is a bit complex for mental arithmetic. Here are two shortcuts:
Quick Celsius to Fahrenheit
Double the Celsius temperature and add 30. This gives a rough estimate:
- 20°C → 20 × 2 + 30 = 70°F (exact: 68°F)
- 30°C → 30 × 2 + 30 = 90°F (exact: 86°F)
Quick Fahrenheit to Celsius
Subtract 30 from the Fahrenheit temperature and halve it:
- 70°F → (70 − 30) ÷ 2 = 20°C (exact: 21.1°C)
- 90°F → (90 − 30) ÷ 2 = 30°C (exact: 32.2°C)
Oven Temperature Guide
| °C | °F | Gas Mark | Description |
|---|---|---|---|
| 150°C | 300°F | 2 | Low/Slow |
| 180°C | 350°F | 4 | Moderate |
| 200°C | 400°F | 6 | Hot |
| 220°C | 425°F | 7 | Very Hot |
Which countries use Celsius vs Fahrenheit?
Almost every country in the world uses Celsius for everyday temperature measurement. The United States is the primary exception, using Fahrenheit for weather, cooking, and body temperature. The Bahamas, Belize, and the Cayman Islands also use Fahrenheit.
Scientists worldwide use Celsius (or Kelvin for absolute temperatures), regardless of country.