How to convert Fahrenheit to Celsius
To convert Fahrenheit to Celsius, subtract 32 first, then multiply by 5/9. The order matters: subtracting removes the 32-degree offset between the two scales, and multiplying by 5/9 rescales the remaining difference, because a Fahrenheit degree is smaller than a Celsius degree.
For example, (98.6°F − 32) × 5/9 = 37°C. Room temperature of 68°F is 20°C. A rough shortcut for weather is to subtract 30 and halve — 70°F → about 20°C — close but not exact.
Where you’ll use Fahrenheit to Celsius
People converting Fahrenheit to Celsius are usually taking a US figure into the metric scale the rest of the world uses. Common situations:
- Travel and weather: a visitor to the US, or someone reading a US forecast, translating it into familiar Celsius.
- Fever and health: converting a US thermometer reading to check it against the 37°C normal and 38°C fever thresholds used in metric countries.
- Recipes: a US recipe listing the oven at, say, 375°F when your oven is marked in Celsius.
- Appliances and thermostats: setting equipment brought over from the US.
- School and science: converting textbook values into SI units.
The Fahrenheit and Celsius scales
The Fahrenheit scale, from the early 1700s, fixes water’s freezing point at 32° and boiling at 212°, a span of 180 degrees. The Celsius scale places those same points at 0° and 100°, a span of 100 degrees. Since 100 ÷ 180 = 5/9, each Fahrenheit degree is only 5/9 of a Celsius degree — that fraction, plus the 32° offset, is the whole conversion.
Fahrenheit to Celsius conversion table
| Fahrenheit | Celsius |
|---|
Everyday temperatures in both scales
| What it is | Fahrenheit | Celsius |
|---|---|---|
| Freezing water | 32 °F | 0 °C |
| Cold day | 41 °F | 5 °C |
| Room temperature | 68 °F | 20 °C |
| Warm day | 86 °F | 30 °C |
| Body temperature | 98.6 °F | 37 °C |
| Fever threshold | 100.4 °F | 38 °C |
| Boiling water | 212 °F | 100 °C |
Worked examples
Convert 100°F to Celsius
(100 − 32) × 5/9 = 37.8°C — a warm day or a slight fever.
Convert 212°F to Celsius
(212 − 32) × 5/9 = 100°C, the boiling point of water.
Convert 350°F (a common oven setting) to Celsius
(350 − 32) × 5/9 = 176.7°C, usually rounded to 180°C in recipes.
Frequently asked questions
100°F is about 37.8°C.
32°F equals 0°C, the freezing point of water.
Because the Fahrenheit scale starts its freezing point at 32 rather than 0, you remove that offset before applying the 5/9 scaling.
98.6°F (37°C) is the traditional average, but normal healthy temperature actually ranges from roughly 97°F to 99°F (36.1°C to 37.2°C) and varies by time of day and person.