How to convert Celsius to Fahrenheit
Example: 25 °C × 1.8 + 32 = 77 °F — a pleasant summer day. The shortcut double and add 30 gives 80 °F: about 3° high here, exact at 10 °C, and good enough for conversation anywhere between freezing and body heat.
°C to °F conversion chart
| °C | °F | What it feels like |
|---|---|---|
| -40 | -40 | The crossover point — same in both scales |
| -18 | -0.4 | Home freezer |
| 0 | 32 | Water freezes |
| 10 | 50 | Chilly day — jacket weather |
| 20 | 68 | Comfortable room |
| 25 | 77 | Warm day |
| 30 | 86 | Hot day |
| 37 | 98.6 | Body temperature |
| 40 | 104 | Heatwave / high fever |
| 100 | 212 | Water boils (at sea level) |
| 180 | 356 | Moderate oven |
| 220 | 428 | Hot oven — pizza territory |
Why 9/5 and 32?
Fahrenheit set his zero at the coldest brine mixture he could reproduce and put body temperature near 96; water then froze at 32° and boiled at 212° — 180 degrees apart. Celsius simply defined freezing as 0 and boiling as 100 — 100 degrees apart. The ratio 180/100 = 9/5 converts the step size, and +32 aligns the freezing points. The scales cross at −40°, the only temperature identical in both.
Oven translation
Recipes crossing the Atlantic need the oven row above most: 160 °C = 320 °F, 180 °C = 356 °F (usually printed as 350), 200 °C = 392 °F (≈ 400), 220 °C = 428 °F (≈ 425). Cookbooks round to the nearest 25 °F — your cake won't notice.
Frequently asked questions
What is the formula for Celsius to Fahrenheit?
Multiply by 9/5 (that is, 1.8) and add 32. So 20 °C → 20 × 1.8 + 32 = 68 °F. The reverse subtracts 32 first, then divides by 1.8.
What is 37 °C in Fahrenheit?
37 °C = 98.6 °F — the textbook body temperature. A fever threshold of 38 °C corresponds to 100.4 °F, the number US pediatricians quote.
What temperature is the same in both scales?
−40°. Below the crossover, Fahrenheit readings are lower than Celsius; above it, higher. It's also a handy sanity check for any converter.
What's the fastest mental conversion?
Double the Celsius and add 30. It's exact at 10 °C (50 °F), reads ~2–4° high through warm weather, and always lands close enough to pick clothing by.
Why does the US use Fahrenheit?
It was the established scale of the British Empire when the US formed, and the US never completed metrication. Fahrenheit fans note its 0–100 span neatly covers 'very cold to very hot' for weather; the rest of the world shrugs in Celsius.