🌡️ Celsius/Fahrenheit Converter
Convert between Celsius (°C) and Fahrenheit (°F) temperatures.
How the Temperature Scales Differ
Celsius and Fahrenheit are both linear scales, but they place zero differently and use different step sizes. Celsius sets 0 at the freezing point of water and 100 at boiling; Fahrenheit sets 32 and 212. One Celsius degree is therefore 1.8 Fahrenheit degrees, which is why the conversion needs a multiplier and an offset rather than a simple ratio.
Conversion Formula
Fahrenheit = Celsius × 9/5 + 32, and Celsius = (Fahrenheit − 32) × 5/9. Kelvin = Celsius + 273.15. The offset is applied after scaling, which is why 0 °C is 32 °F rather than 0.
Worked Examples
20 °C → 20 × 9/5 + 32 = 68 °F
98.6 °F → (98.6 − 32) × 5/9 = 37 °C, normal body temperature
Key Temperatures
| Description | °C | °F |
|---|---|---|
| Water boiling point | 100°C | 212°F |
| Body temperature | 36.5°C | 97.7°F |
| Water freezing point | 0°C | 32°F |
| Absolute zero | −273.15°C | −459.67°F |
Where People Get It Wrong
A difference of 1 °C is a difference of 1.8 °F, but a temperature of 1 °C is 33.8 °F — never convert a difference with the formula for absolute temperatures. Doubling °C does not double °F either, because of the offset. Kelvin uses the same step as Celsius but starts at absolute zero, so it is the right unit for physical calculations where ratios matter.
Frequently Asked Questions
- What is the formula to convert Celsius to Fahrenheit?
- Multiply by 9/5 and add 32: 20 °C → 20 × 1.8 + 32 = 68 °F. To go back, subtract 32 and multiply by 5/9.
- Is 37 °C exactly 98.6 °F?
- By the formula yes, and that is the conventional normal body temperature. Real body temperature varies between about 36.1 °C and 37.2 °C (97–99 °F) through the day.
- At what temperature are Celsius and Fahrenheit equal?
- At −40: −40 °C = −40 °F. It is the only point where the two scales read the same number.