The formula, and a shortcut you can do in your head
Multiply Celsius by 1.8 (that is 9/5), then add 32. Do it in that order: scale first, add 32 last. For a fast estimate, double it and add 30: 20 C → 40 + 30 = 70 F, close to the exact 68. The trick is spot-on at 10 C and drifts by a couple of degrees at the extremes.
Weather, in 5-degree steps
| °C | °F | Feels like |
|---|---|---|
| −10° | 14° | Cold winter day |
| 0° | 32° | Freezing point |
| 10° | 50° | Light jacket |
| 20° | 68° | Room temperature |
| 25° | 77° | Warm |
| 30° | 86° | Hot summer day |
| 40° | 104° | Extreme heat |
Body temperature and oven settings
| What | °C | °F |
|---|---|---|
| Normal body temperature | 37° | 98.6° |
| Fever threshold | 38° | 100.4° |
| Water boils | 100° | 212° |
| Oven – moderate (cakes) | 180° | 356° (≈350) |
| Oven – hot (roasting) | 220° | 428° (≈425) |
| Oven – pizza | 232° | 450° |
Oven dials in Fahrenheit tend to sit on round numbers (325, 350, 375, 400, 425, 450), so Celsius settings get rounded to the nearest one rather than converted exactly.
Two things people get wrong
- A change is not a reading. A rise of 5 C is a rise of 9 F, but a temperature of 5 C is 41 F. Converting a difference (times 1.8 only) is not the same as converting a reading (times 1.8, plus 32).
- Below −40, the order flips. Above −40° the Fahrenheit number is larger; below it, smaller. At exactly −40° the two scales meet: −40 C = −40 F.
Common questions
What is the formula for Celsius to Fahrenheit?
Fahrenheit equals Celsius times 1.8, plus 32 (the same as times 9/5, plus 32). Multiply first, then add. For example, 25 C times 1.8 is 45, plus 32 gives 77 F.
What is 37 C in Fahrenheit?
37 C is 98.6 F, the traditional figure for normal body temperature. A fever starts at 38 C, which is 100.4 F.
What is 180 C in Fahrenheit for an oven?
180 C is 356 F, which recipes usually round to 350 F. It is the standard moderate setting for cakes and baking.
