Convert Fahrenheit to Celsius
Fahrenheit to Celsius with the subtraction shown in full, a slider covering weather through oven range, and Kelvin alongside.
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Thermostats, weather forecasts, US recipes and thermometers.
°C = (°F − 32) × 5/9 °C = (98.6 − 32) × 5/9 °C = (98.6 − 32) ÷ 1.8 = 37.00 °C
| degrees Fahrenheit | degrees Celsius |
|---|---|
| −40 °F | −40.00 °C |
| 0 °F | −17.78 °C |
| 20 °F | −6.67 °C |
| 32 °F | 0.00 °C |
| 40 °F | 4.44 °C |
| 50 °F | 10.00 °C |
| 60 °F | 15.56 °C |
| 68 °F | 20.00 °C |
| 72 °F | 22.22 °C |
| 80 °F | 26.67 °C |
| 90 °F | 32.22 °C |
| 98.6 °F | 37.00 °C |
| 100.4 °F | 38.00 °C |
| 104 °F | 40.00 °C |
| 212 °F | 100.00 °C |
| 350 °F | 176.67 °C |
| 400 °F | 204.44 °C |
| 425 °F | 218.33 °C |
Subtract first, then scale
Going from Fahrenheit to Celsius reverses both steps of the other direction, and the order matters:
°C = (°F − 32) × 5/9
Take off the 32 to line up the zero points, then shrink by 5/9 because a Fahrenheit degree is smaller. Dividing by 1.8 is the same operation and easier on a calculator. Scaling before subtracting is the classic error and produces an answer 14.2 degrees too low, every time.
Thermostats, weather and comfort
| °F | °C | Feels like |
|---|---|---|
| 0 | -17.8 | Severe cold |
| 32 | 0 | Freezing |
| 50 | 10 | Coat weather |
| 60 | 15.6 | Cool spring day |
| 68 | 20 | Standard room temperature |
| 72 | 22.2 | The default US thermostat setting |
| 80 | 26.7 | Warm |
| 90 | 32.2 | Hot |
| 100 | 37.8 | Very hot; above body temperature |
The Fahrenheit scale is arguably better tuned to human weather: 0 to 100 °F covers "unbearably cold" to "unbearably hot" in most inhabited places, while the same span in Celsius is a cramped −18 to 38.
The mental shortcut
Subtract 30 and halve. 70 → 20 (true 21.1). 90 → 30 (true 32.2). 50 → 10 (true 10). It is a degree or two low in the middle of the range and exact at 50, which is more than enough to decide what to wear.
Cooking with a US recipe
American oven temperatures come in 25 °F steps that convert to untidy Celsius numbers, which is why every European edition rounds them:
- 325 °F = 162.8 °C, written as 160 °C (gas 3)
- 350 °F = 176.7 °C, written as 180 °C (gas 4)
- 375 °F = 190.6 °C, written as 190 °C (gas 5)
- 400 °F = 204.4 °C, written as 200 °C (gas 6)
- 425 °F = 218.3 °C, written as 220 °C (gas 7)
If you have a fan oven, subtract a further 20 °C from those figures. Our oven temperature converter does the whole chain including gas marks.
Fahrenheit's odd zero
Daniel Fahrenheit set his zero at the temperature of an ice, water and ammonium chloride brine — the coldest thing he could reliably reproduce in 1724 — and 96 at approximately human body temperature. Neither landmark survives in the modern definition, which is now fixed by reference to the Celsius scale, and that history is precisely why none of the numbers line up neatly.
Questions
What is the Fahrenheit to Celsius formula?
°C = (°F − 32) × 5/9. Subtract first, then scale — doing it the other way round is the classic error and gives an answer roughly 18 degrees out.
What is 98.6 °F in Celsius?
Exactly 37 °C. The 98.6 figure is a conversion of a round 37, not an independent measurement, which is why it looks suspiciously precise.
What is a comfortable thermostat setting in Celsius?
68 °F is 20 °C and 72 °F is 22.2 °C. Most European heating advice lands on 19–21 °C for living rooms, which is 66–70 °F.
How cold is 0 °F?
−17.8 °C. Fahrenheit's zero was set by a brine freezing mixture, not by water, which is why neither of that scale's landmarks lines up with anything obvious in Celsius.