US weather apps and recipes from abroad often list temperatures in Fahrenheit (°F), which can be hard to picture. Here's the exact formula and a quick way to estimate.
The exact formula
Celsius = (Fahrenheit − 32) × 5/9. For example, 100°F is (100−32)×5/9 ≈ 37.8°C.
| Fahrenheit | Celsius | Note |
|---|---|---|
| 32°F | 0°C | Water freezes |
| 68°F | 20°C | Comfortable room temperature |
| 98.6°F | 37°C | Average human body temperature |
| 212°F | 100°C | Water boils |
| 350°F | 177°C | Common oven recipe temperature |
A quick mental-math shortcut
When an exact calculation is inconvenient, subtract 30 and divide by 2. For example, 70°F becomes (70−30)/2 = 20°C, which is close to the real value (21.1°C). If a US weather app says "70 degrees," that's roughly 20°C.
Why the US still uses Fahrenheit
Fahrenheit was devised in the early 18th century by Daniel Gabriel Fahrenheit to fit typical human body temperature and everyday weather swings neatly into a whole-number range. Nearly every other country uses Celsius, based on water's freezing and boiling points, as the standard.
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