Unit Converter · Practical guide
How to Convert Celsius to Fahrenheit
Multiply by 9/5 and add 32 — the exact formula, worked examples, and a quick reference table.
At a glance
The Formula
To convert Celsius to Fahrenheit, use °F = °C × 9/5 + 32. Multiplying by 9/5 (that is, 1.8) handles the different degree sizes, and adding 32 handles the different zero points. Worked example: 37 °C × 9/5 + 32 = 66.6 + 32 = 98.6 °F, normal body temperature.
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Why Not Just Multiply?
The two scales start at different places: 0 °C is already 32 °F. A plain multiplier would send 0 °C to 0 °F, which is wrong by 32 degrees. The converter above applies the full formula automatically — select Temperature, enter the value, and choose C and F.
Common Temperature Reference
| Celsius | Fahrenheit | Reference |
|---|---|---|
| -40 °C | -40 °F | Where the scales meet |
| 0 °C | 32 °F | Water freezes |
| 20 °C | 68 °F | Room temperature |
| 37 °C | 98.6 °F | Body temperature |
| 100 °C | 212 °F | Water boils |
| 180 °C | 356 °F | Common oven setting |
A Mental-Math Shortcut
For a fast estimate, double the Celsius value and add 30. For 20 °C that gives 70 °F — close to the exact 68 °F. The shortcut drifts about 2 °F at room temperature and more at extremes, so use the exact formula (or the converter) for cooking, science, or weather records.
Converting a Temperature Difference
A difference skips the offset: multiply by 9/5 only. A 10 °C warming trend is an 18 °F rise, and a recipe asking for a 5 °C adjustment means 9 °F.
Frequently Asked Questions
What is 180 Celsius in Fahrenheit?
180 °C × 9/5 + 32 = 356 °F. It is one of the most common moderate-oven settings in recipes.
How do I convert Fahrenheit back to Celsius?
Use the inverse formula: °C = (°F − 32) × 5/9. For example, 68 °F is (68 − 32) × 5/9 = 20 °C.
At what temperature are Celsius and Fahrenheit equal?
At −40 degrees. Solving C = C × 9/5 + 32 gives −40, so −40 °C and −40 °F are the same temperature.
How does Kelvin fit in?
Kelvin uses Celsius-sized degrees with a different zero: K = °C + 273.15. So 0 °C is 273.15 K and 100 °C is 373.15 K.