Celsius to Fahrenheit Converter

Convert between Celsius and Fahrenheit — formula and step-by-step included

Enter a temperature in °C or °F and get the converted value instantly, with the complete formula and step-by-step calculation.

Try: −40 · 0 · 20 · 37 · 100

Conversion curve

About the Celsius and Fahrenheit scales

Celsius (°C), formerly Centigrade, is the SI temperature scale. It sets 0°C as the freezing point and 100°C as the boiling point of water at standard atmospheric pressure, giving a 100-degree span between the two reference points.

Fahrenheit (°F) is used primarily in the United States and a few Caribbean nations. Its reference points are 32°F (water freezes) and 212°F (water boils) — a span of 180°F for the same interval. One Fahrenheit degree is therefore 5/9 of a Celsius degree.

The two scales intersect at −40°, the only temperature with the same value in both units.

Reference temperatures

Reference point °C °F
Absolute zero −273.15 −459.67
Water freezes 0 32
Room temperature 20 68
Body temperature 37 98.6
Water boils 100 212

Frequently asked questions

40°C = 104°F. Using the formula: 40 × 9/5 + 32 = 72 + 32 = 104.
Normal body temperature is about 37°C, which equals 98.6°F.
−40° is the only temperature equal in both scales: −40°C = −40°F.
Multiply by 9/5 (1.8) then add 32. Example: 100°C → 100 × 1.8 + 32 = 212°F.
Subtract 32 then multiply by 5/9. Example: 98.6°F → (98.6 − 32) × 5/9 = 37°C.
Double the Celsius value and add 30 for a rough estimate. Example: 20°C → 20 × 2 + 30 = 70°F (exact: 68°F).

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