Fahrenheit to Celsius Converter
Convert Fahrenheit to Celsius with °C = (°F − 32) × 5/9. Includes a weather and body-temperature table, a quick estimate you can do in your head, and worked examples.
Fahrenheit to Celsius
Formula
Subtract 32 first, then multiply by 5/9.
The order matters. Subtracting 32 lines the two zeros up on the freezing point of water; multiplying by 5/9 then shrinks Fahrenheit's smaller degrees to Celsius-sized ones. Multiplying before subtracting gives the wrong answer.
Worked example
Convert a 72 °F thermostat setting:
And a 101 °F fever:
Conversion table
| Fahrenheit (°F) | Celsius (°C) |
|---|---|
| -40 | -40 |
| 0 | -17.77778 |
| 20 | -6.666667 |
| 32 | 0 |
| 50 | 10 |
| 68 | 20 |
| 72 | 22.22222 |
| 80 | 26.66667 |
| 98.6 | 37 |
| 100 | 37.77778 |
| 104 | 40 |
| 150 | 65.55556 |
| 212 | 100 |
| 350 | 176.6667 |
Do it in your head
Subtract 30, then halve. For 72 °F that gives 21 °C against a true 22.2 °C — fine for deciding whether you need a coat. The estimate reads a little low in mild weather and a little high in cold weather.
For an exact mental method: subtract 32, halve it, then add a ninth of that half back. For 72 °F: 40 → 20 → 20 + 2.2 = 22.2 °C.
Reference temperatures
- Very cold winter day — 0 °F = −17.8 °C
- Water freezes — 32 °F = 0 °C
- Chilly day — 50 °F = 10 °C
- Mild day — 68 °F = 20 °C
- Room temperature — 72 °F = 22.2 °C
- Warm day — 80 °F = 26.7 °C
- Body temperature — 98.6 °F = 37 °C
- Fever worth watching — 104 °F = 40 °C
- Water boils — 212 °F = 100 °C
- Baking a cake — 350 °F = 176.7 °C
Body temperature and fever
Fahrenheit's finer degrees are why US clinical readings are quoted in it: a single Fahrenheit degree is a smaller step, so a fever reads in whole numbers. The Celsius equivalents are worth memorising — 100 °F is 37.8 °C, 101 °F is 38.3 °C, 102 °F is 38.9 °C and 103 °F is 39.4 °C. Clinical advice thresholds differ by country, so check local guidance rather than converting a rule of thumb.
FAQ
What is 1 °F in Celsius? −17.2 °C. But a difference of 1 °F is a difference of only 0.556 °C — the 32 applies to absolute readings, not to gaps between them.
Why subtract 32 before multiplying? Because the scales have different zero points. The subtraction moves Fahrenheit's zero onto Celsius's zero; only then is the scaling valid.
What is 32 °F in Celsius? Exactly 0 °C, the freezing point of water.
Is there a temperature where both scales agree? Yes, −40. It reads −40 in both.