How to convert Celsius to Fahrenheit
Fahrenheit is the everyday temperature scale in the United States, while nearly everyone else — Europe, Latin America, Asia — reports temperatures in Celsius. That mismatch shows up constantly: a weather app abroad says 30 °C and you need to know whether to pack shorts, a British baking recipe asks for a 180 °C oven, or a doctor overseas tells you a child’s temperature is 38 degrees.
The two scales are related by a simple linear formula:
- Celsius to Fahrenheit:
°F = °C × 9/5 + 32 - Fahrenheit to Celsius:
°C = (°F − 32) × 5/9
Multiplying by 9/5 is the same as multiplying by 1.8, which is often faster on a calculator.
How to use the converter
- Type a temperature into either field — Celsius or Fahrenheit, whichever you have.
- The other field updates instantly; the conversion works in both directions.
- Check the result cards below for the Kelvin equivalent and the quick “double it and add 30” estimate.
- Or tap one of the common-temperature buttons (freezing, room, body, boiling, oven) to load a reference point in one click.
Worked example
A European recipe says to bake at 180 °C — what do you set an American oven to? Step by step: 180 × 9 = 1,620; 1,620 ÷ 5 = 324; 324 + 32 = 356 °F. In practice you’d set the dial to 350 °F, the closest standard mark, which is why so many US recipes call for exactly that. Going the other way, a “hot” 400 °F oven works out to (400 − 32) × 5/9 = 368 × 5/9 ≈ 204 °C, so European cookbooks round it to 200 °C.
Quick reference table
| °C | °F | What it feels like |
|---|---|---|
| −40 | −40 | The scales cross — same number |
| −18 | −0.4 | Home freezer (about 0 °F) |
| 0 | 32 | Water freezes |
| 10 | 50 | Chilly day, light jacket |
| 15 | 59 | Mild spring day |
| 20 | 68 | Room temperature |
| 25 | 77 | Warm and pleasant |
| 30 | 86 | Hot summer day |
| 37 | 98.6 | Normal body temperature |
| 37.8 | 100 | Equals 100 °F |
| 100 | 212 | Water boils (at sea level) |
| 180 | 356 | Moderate oven (US recipes: 350 °F) |
| 200 | 392 | Hot oven (US recipes: 400 °F) |
For fever checks, the common threshold of 38 °C converts to 100.4 °F. This tool translates units only — it is not medical advice, so see a doctor for a persistent fever or any worrying symptoms.
Frequently asked questions
Is there a quick mental trick for Celsius to Fahrenheit?
Yes: double the Celsius number and add 30. For 22 °C: 22 × 2 + 30 = 74, close to the exact 71.6 °F. It works well for weather temperatures roughly between 0 and 35 °C, but drifts as numbers grow — at oven temperatures it’s far off (180 °C would give 390 instead of 356). Use the full formula, or this converter, when precision matters.
What is 98.6 °F in Celsius?
Exactly 37 °C: (98.6 − 32) × 5/9 = 66.6 × 5/9 = 37. That’s the classic “normal” body temperature printed on American thermometers, though normal readings vary somewhat by person, time of day and measurement site.
Why does the US still use Fahrenheit?
Daniel Gabriel Fahrenheit proposed his scale in 1724, and it became the standard across the British Empire, including the American colonies. Most countries later switched to Celsius as part of metrication, but the United States never completed that shift, so Fahrenheit remains its everyday scale for weather, cooking and medicine. A few neighbors with strong US ties — such as Belize, the Bahamas and the Cayman Islands — still use it in daily life too.
What is absolute zero on each scale?
Absolute zero, the coldest temperature physically possible, is −273.15 °C, which equals −459.67 °F and 0 K on the Kelvin scale. No real temperature can go below it — if the converter warns you about that, double-check the number you entered.
At what temperature do Celsius and Fahrenheit match?
At −40 degrees: −40 °C = −40 °F. It’s the only point where both scales read the same, and the formula confirms it: −40 × 9/5 + 32 = −72 + 32 = −40.