Fahrenheit to Celsius — °F ↔ °C Converter & Formula
Convert between Fahrenheit, Celsius, and Kelvin — plus common reference points for everyday life and lab work.
The Formula
The two scales share the same degree size in spirit — Celsius anchors 0° at water's freezing point and 100° at boiling. Fahrenheit anchors 32° at freezing and 212° at boiling. The offset (32) and ratio (9/5) account for both the different starting points and different step sizes:
- °F to °C: subtract 32, then multiply by 5/9 — or divide by 1.8
- °C to °F: multiply by 9/5 (or 1.8), then add 32
- °C to K: add 273.15 (exact definition of Kelvin)
Quick mental shortcut when you need a rough answer fast: subtract 30 from °F, then halve it. Example: 80°F → 50 ÷ 2 = 25°C (actual answer: 26.7°C — close enough to know it's a warm day, not to put in a chem report).
Reference Points
| Description | °F | °C | Kelvin |
|---|---|---|---|
| Absolute zero | −459.67°F | −273.15°C | 0 K |
| Water freezes | 32°F | 0°C | 273.15 K |
| Cold room | 59°F | 15°C | 288.15 K |
| Room temperature | 72°F | 22.2°C | 295.35 K |
| Body temperature | 98.6°F | 37°C | 310.15 K |
| Low fever | 100.4°F | 38°C | 311.15 K |
| Standard lab temp | 77°F | 25°C | 298.15 K |
| Water boils (sea level) | 212°F | 100°C | 373.15 K |
Why International Students Use This Most
If you grew up outside the US, Fahrenheit is non-intuitive. A weather report saying "high of 85°F today" means nothing immediately — you need to know that's about 29°C, a warm summer day. Similarly, a US lab protocol might specify incubating samples "at 98°F" and you need to confirm that's 37°C (body temp, not a hot water bath).
If you need to convert weight and volume for lab experiments too, the full unit converter handles all categories on one page.