Unit Conversions
How to Convert Fahrenheit to Celsius
July 10, 2025·3 min read
The formula for converting Fahrenheit to Celsius, quick mental math shortcuts, and a reference table of important temperatures in both scales.
If you've ever looked at an American weather forecast and wondered what 95°F feels like, or tried to follow a US recipe calling for a 350°F oven, you need the Fahrenheit-to-Celsius conversion. Here it is.
The Formula
°C = (°F − 32) × 5/9. Or equivalently: °C = (°F − 32) ÷ 1.8.
Worked Examples
- 98.6°F (body temperature): (98.6 − 32) × 5/9 = 66.6 × 0.556 = 37°C
- 350°F (moderate oven): (350 − 32) × 5/9 = 318 × 0.556 = 176.7°C (≈ 177°C)
- 72°F (comfortable room): (72 − 32) × 5/9 = 40 × 0.556 = 22.2°C
- 32°F (freezing): (32 − 32) × 5/9 = 0°C
Mental Math Shortcut
Subtract 30, then halve the result. For 80°F: 80 − 30 = 50, halved = 25°C (actual: 26.7°C). Rough but fast — good enough for weather estimates.
Important Temperature Reference Points
- 0°F = −17.8°C (dangerously cold)
- 32°F = 0°C (water freezes)
- 98.6°F = 37°C (normal body temperature)
- 212°F = 100°C (water boils at sea level)
- 451°F = 233°C (paper burns — yes, the Bradbury reference)