What this does
Converts Celsius to Fahrenheit as you type. The formula is °F = °C × 9/5 + 32 — scale by 1.8, then shift by 32 because the two scales put their zero points in different places.
The fast mental version
Double the Celsius and add 30 for a rough answer: 20 °C → 40 + 30 = 70 °F (true value 68). It drifts by a few degrees at the extremes because the real multiplier is 1.8, not 2, but for "what should I wear?" it's close enough.
Reference points worth memorizing
- 0 °C = 32 °F — water freezes
- 20 °C = 68 °F — comfortable room temperature
- 37 °C = 98.6 °F — normal body temperature
- 38 °C = 100.4 °F — the usual fever threshold
- 100 °C = 212 °F — water boils (at sea level)
- 180 °C = 356 °F — a moderate oven; 200 °C = 392 °F
Is there a temperature where both scales agree?
Yes — −40 °C = −40 °F. It's the one point where the lines cross, which is why "forty below" needs no unit. You can verify it above: type −40 on either side.
Why does Fahrenheit start at 32 for freezing?
Fahrenheit built his scale around a freezing brine mixture (0 °F) and body temperature, which left water's freezing point at the awkward-looking 32. Celsius later pegged 0 and 100 to water's freezing and boiling points, giving the cleaner scale most of the world uses. The 32 offset is the fossil of that history.
Going the other way?
Use the swap button, or the Fahrenheit to Celsius page with the US-weather references. Kelvin is in the full converter's temperature category.