Celsius to Fahrenheit Converter

Multiply by 9/5 and add 32.

The 9/5 is there because a Fahrenheit degree is smaller: 100 Celsius degrees cover the same span as 180 Fahrenheit degrees. The 32 is there because the two scales put zero in different places — Celsius at the freezing point of water, Fahrenheit 32 degrees below it.

Convert a 21 °C room:

And a 180 °C oven:

Double the Celsius figure and add 30. For 21 °C that gives 72 °F against a true 69.8 °F — close enough to decide what to wear. The shortcut works because doubling is near enough to 1.8× over everyday temperatures, and the extra 2 degrees of error from the multiplier roughly offsets using 30 instead of 32.

For a cleaner version: double, subtract a tenth of the result, then add 32. For 21 °C: 42 − 4.2 + 32 = 69.8 °F, which is exact.

• Water freezes — 0 °C = 32 °F
• Cold winter day — −10 °C = 14 °F
• Fridge — 4 °C = 39.2 °F
• Mild spring day — 15 °C = 59 °F
• Comfortable room — 21 °C = 69.8 °F
• Human body — 37 °C = 98.6 °F
• Hot summer day — 35 °C = 95 °F
• Water boils — 100 °C = 212 °F
• Moderate oven — 180 °C = 356 °F

At −40, both scales read the same number: −40 °C = −40 °F. It is the one point where the formula returns its own input, and it is a useful sanity check on any conversion you write yourself.

What is 1 °C in Fahrenheit? 33.8 °F. Note that a change of 1 °C is a change of 1.8 °F — the 32 only applies to absolute temperatures, not to differences.

What is a normal body temperature in Fahrenheit? 37 °C converts to 98.6 °F.

Which countries use Fahrenheit? The United States and its territories, plus the Cayman Islands and Liberia. Everywhere else reports weather in Celsius.

Why is the freezing point of water 32 °F? Fahrenheit set his zero using a freezing brine mixture, not pure water, so the freezing point of water landed at an arbitrary-looking 32.