Fahrenheit ↔ Celsius
Convert between °F and °C
Fahrenheit ↔ Celsius
Quick Facts
- •32°F = 0°C (freezing)
- •212°F = 100°C (boiling)
- •−40°F = −40°C (they intersect!)
Fahrenheit vs Celsius
The Fahrenheit scale is used primarily in the US. Water freezes at 32°F (0°C) and boils at 212°F (100°C). The formula is: °C = (°F − 32) × 5/9. Some easy reference points: 72°F = 22°C (room temperature), 98.6°F = 37°C (body temperature).
History
Daniel Fahrenheit created his scale in 1724. Anders Celsius proposed his scale in 1742. Most of the world adopted Celsius as part of the metric system, while the US retained Fahrenheit for weather and cooking.
Understanding the fahrenheit ↔ celsius
Fahrenheit and Celsius have different zero points as well as different step sizes, so you cannot convert by multiplying alone. The two scales cross at minus 40 degrees, which is the one temperature where both readings are identical.
Worked examples
Converting a 101.5 F fever to Celsius
- 1Subtract 32: 101.5 - 32 = 69.5.
- 2Multiply by 5/9: 69.5 × 5 ÷ 9 = 38.6.
101.5 F is 38.6 C, which is a moderate fever.
Converting 20 C room temperature to Fahrenheit
- 1Multiply by 9/5: 20 × 9 ÷ 5 = 36.
- 2Add 32: 36 + 32 = 68.
20 C is 68 F.
The quick mental estimate
- 1To go from Celsius to Fahrenheit, double the number and add 30.
- 2For 22 C: 22 × 2 = 44, plus 30 gives 74 F.
- 3The exact answer is 71.6 F, so the shortcut runs a few degrees high in mild weather.
Double and add 30 is accurate to about 3 degrees between 0 C and 30 C.
Reference temperatures on both scales
| Celsius | Fahrenheit | What it means |
|---|---|---|
| -40 C | -40 F | The scales cross |
| -18 C | 0 F | Home freezer setting |
| 0 C | 32 F | Water freezes |
| 10 C | 50 F | Cool jacket weather |
| 20 C | 68 F | Comfortable room temperature |
| 25 C | 77 F | Warm summer day |
| 30 C | 86 F | Hot day |
| 37 C | 98.6 F | Normal body temperature |
| 38 C | 100.4 F | Fever threshold |
| 100 C | 212 F | Water boils at sea level |
| 180 C | 356 F | Standard baking temperature |
Frequently asked questions
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This calculator is for educational and reference purposes only. Always verify critical calculations independently.