Convert Fahrenheit to Celsius
A free tool that turns any Fahrenheit (°F) reading into Celsius (°C) — accurate for weather, body temperature, and oven settings.
- Celsius (°C)-17.22222
- Fahrenheit (°F)1
- Kelvin (K)255.9278
🔒 Unit conversions are computed in your browser.
The formula and worked examples
To convert Fahrenheit to Celsius, use °C = (°F − 32) × 5/9: subtract 32 first, then multiply by 5 and divide by 9. Water's freezing point, 32°F, becomes (32−32)×5/9 = 0°C. Normal body temperature of 98.6°F works out to (98.6−32)×5/9 = 37.0°C, and a scorching 100°F summer day is (100−32)×5/9 ≈ 37.8°C. Water boils at 212°F, which is exactly 100°C. Type any value into the converter above and it handles the decimals for you.
When you'll actually need it
The US reports weather, cooking, and body temperature in Fahrenheit, so this conversion comes up constantly for travelers and home cooks. A forecast of 90°F means a hot ~32°C day; a recipe calling for a 350°F oven is about 177°C, and 425°F is roughly 218°C. A thermometer reading of 100.4°F is 38.0°C — the usual threshold for a low-grade fever — while a US thermostat set to 68°F is a comfortable 20°C. For a quick estimate, subtract 30 and halve: 70°F ≈ 20°C (21.1°C exactly), close enough to gauge the weather.
Watch out for these
Temperature isn't a simple ratio like length or weight — the two scales are offset by 32 degrees, so 200°F is not twice the Celsius value of 100°F. In fact 100°F is 37.8°C while 200°F is 93.3°C. Always subtract 32 before multiplying by 5/9, never after. One neat fact: −40°F equals −40°C exactly, the single point where both scales meet. Rounding to a whole number is fine for weather, but keep one decimal for body temperature, where half a degree matters.
Frequently asked questions
What is 98.6°F in Celsius?
98.6°F is (98.6−32)×5/9 = 37.0°C, the standard normal body temperature. A reading of 100.4°F comes to 38.0°C, which is commonly treated as the start of a fever.
Is there a quick way to estimate it in my head?
Subtract 30 and halve. For example, 80°F → (80−30)/2 = 25°C (26.7°C exactly). Because you're multiplying by 1/2 instead of the true 5/9, the estimate runs a little low, but it's plenty accurate for reading a weather forecast.
How do I convert oven temperatures?
Common settings are 325°F ≈ 163°C, 350°F ≈ 177°C, 375°F ≈ 191°C, and 425°F ≈ 218°C. Use (°F−32)×5/9, then round to the nearest 5°C since most ovens only adjust in steps.