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Celsius and Fahrenheit are two temperature scales with different zero points and different degree sizes, so converting isn't a simple multiplication — there's an offset too. This tool applies the formula for you, turning Celsius into Fahrenheit and back.
How is it calculated?
The conversion factor
Unlike most conversions, temperature has both a scale factor and an offset:
| Direction | Formula |
|---|---|
| °C → °F | (°C × 9/5) + 32 |
| °F → °C | (°F − 32) × 5/9 |
The scales cross at −40°, where °C and °F read the same.
Common values
| Celsius | Fahrenheit |
|---|---|
| 0 °C | 32 °F |
| 20 °C | 68 °F |
| 37 °C | 98.6 °F |
| 100 °C | 212 °F |
Worked example
Body temperature of 37 °C is (37 × 9/5) + 32 = 98.6 °F. A 72 °F room is (72 − 32) × 5/9 = 22.2 °C. Water freezes at 0 °C / 32 °F and boils at 100 °C / 212 °F.
FAQ
How do I convert Celsius to Fahrenheit?+
Multiply by 9/5 (i.e. 1.8) and add 32. So 25 °C = 25 × 1.8 + 32 = 77 °F. A quick estimate is “double and add 30”.
How do I convert Fahrenheit to Celsius?+
Subtract 32, then multiply by 5/9. For example, 100 °F = (100 − 32) × 5/9 = 37.8 °C.
Why isn't it a simple multiplication?+
Because the two scales have different zero points — 0 °C is 32 °F — so you need an offset of 32 as well as the 9/5 scale factor. That's why the formula has both a multiply and an add.
At what temperature are Celsius and Fahrenheit equal?+
At −40°. Minus 40 degrees Celsius is exactly minus 40 degrees Fahrenheit — the one point where the two scales meet.
What is a normal body temperature in Fahrenheit?+
The classic figure is 98.6 °F, which is 37 °C. Normal readings actually range a little either side of that.