What this does
Converts Fahrenheit to Celsius as you type. The formula is °C = (°F − 32) × 5/9 — subtract the 32-degree offset first, then scale down by 1.8.
The fast mental version
Subtract 30 and halve: 70 °F → 40 ÷ 2 = 20 °C (true value 21). It's a couple of degrees high in cold weather and low in hot weather, but it's instant and good enough to decide on a jacket.
US weather and health in Celsius
- 32 °F = 0 °C — freezing
- 70 °F = 21.1 °C — a mild room
- 90 °F = 32.2 °C — a hot summer day
- 98.6 °F = 37 °C — normal body temperature
- 100.4 °F = 38 °C — fever threshold
- 350 °F = 176.7 °C — the default US baking temperature
How do I convert an oven recipe from °F to °C?
Run the temperature through the formula and round to a tidy number ovens actually have: 350 °F ≈ 177 °C, dialed to 180 °C; 400 °F ≈ 204 °C → 200 °C; 425 °F ≈ 218 °C → 220 °C. If the oven is fan-assisted (convection), drop another ~20 °C from these.
Is a 1-degree change the same size in both scales?
No — a Fahrenheit degree is smaller. A change of 1 °C equals 1.8 °F, so a forecast that swings "10 degrees" means very different things depending on the scale. That 5/9 factor is exactly why fevers are tracked in tenths of a degree Celsius.
Where do both scales read the same?
At −40° — minus forty Celsius is minus forty Fahrenheit. Type −40 above to see it. Everywhere else the numbers diverge.
Need Celsius back to Fahrenheit?
Swap the sides above, or open the Celsius to Fahrenheit page. Kelvin is available in the full converter.