Temperature / °C → °F
Convert Celsius to Fahrenheit
Compare weather forecasts and thermostat settings. Temperature scales have different zero points: multiply Celsius by 9/5, then add 32.
Reverse: Fahrenheit to Celsius →
How to convert Celsius to Fahrenheit
This converter works with temperature readings, not temperature differences. It allows mathematical inputs below absolute zero; those results do not represent physically possible thermodynamic temperatures.
Use x for the value in °C, b for the intermediate value in °C, and y for the result in °F.
°F = (°C × 9/5) + 32
Worked examples
20 °C ≈ 68 °F
Step 1: (20 × 1) ≈ 20 °C.
Step 2: (20 − (-17.7777777778)) ÷ 0.555555555556 ≈ 68 °F.40 °C ≈ 104 °F
Step 1: (40 × 1) ≈ 40 °C.
Step 2: (40 − (-17.7777777778)) ÷ 0.555555555556 ≈ 104 °F.
Results are rounded to 12 significant digits. Converting units does not increase the precision of the original measurement. Very large or small values outside JavaScript’s finite numeric range are rejected.
About Celsius
Celsius describes temperature on a scale with the same interval size as kelvin. A Celsius reading is 273.15 lower than the corresponding kelvin reading.
About Fahrenheit
Fahrenheit uses smaller degree intervals than Celsius: a change of 9 °F is a change of 5 °C. Readings also require a zero-point adjustment.
Definitions and sources
Temperature readings and temperature changes
Converting meters into feet only needs a scale factor. Temperature is different: Celsius and Fahrenheit have both different degree sizes and different zero points.
Celsius to Fahrenheit
Multiply the Celsius reading by 9/5, then add 32:
°F = (°C × 9/5) + 32
For a 20 °C room, the calculation is (20 × 1.8) + 32 = 68 °F. Try it in the Celsius to Fahrenheit converter.
Fahrenheit to Celsius
Reverse those operations in the reverse order. Subtract 32 first, then multiply by 5/9:
°C = (°F − 32) × 5/9
A reading of 68 °F becomes (68 − 32) × 5/9 = 20 °C. Use the Fahrenheit to Celsius converter for other readings.
A reading and a change are different
A reading of 10 °C equals 50 °F. But a rise of 10 °C equals a rise of 18 °F.
The offset disappears when subtracting one temperature from another. For temperature changes, multiply by 9/5 or 5/9 without adding or subtracting 32. ExactUnit’s temperature converter works with readings.
A useful crossing point
At −40 degrees, both scales show the same number. Substituting −40 into either formula gives −40 on the other scale. This is a useful check when testing a conversion formula.
Check whether a formula requires an absolute temperature or a temperature difference when using this result in physics calculations.
Celsius to Fahrenheit reference table
| Celsius (°C) | Fahrenheit (°F) |
|---|---|
| -40 | -40 |
| 0 | 32 |
| 20 | 68 |
| 32 | 89.6 |
| 68 | 154.4 |
| 100 | 212 |
| 212 | 413.6 |
Browse every temperature conversion →