Convert Celsius to Fahrenheit: Easy Formula & Quick Reference

Converting Celsius to Fahrenheit is one of the most common temperature conversions, especially for travelers between the US and the rest of the world. Here is the exact formula and an easy mental math trick.

The Formula

°F = (°C × 9/5) + 32

To convert Fahrenheit to Celsius:
°C = (°F − 32) × 5/9

Mental Math Shortcut

For a quick estimate: double the Celsius temperature, add 30. This gives you an approximate Fahrenheit value. For example, 20°C → 20×2 = 40 → 40+30 = 70°F (actual is 68°F — close enough for most purposes).

Common Temperature Conversions

0°C = 32°F (freezing point of water)
10°C = 50°F
20°C = 68°F (room temperature)
30°C = 86°F (hot day)
37°C = 98.6°F (normal body temperature)
100°C = 212°F (boiling point of water)
-40°C = -40°F (the point where both scales meet)

When to Use Each Scale

Celsius is used in most countries for weather and cooking. Fahrenheit is standard in the US. Kelvin is used in science. Use our temperature converter above for precise conversions between all three scales.