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Fahrenheit to Celsius (°F to °C)
Convert fahrenheits to celsiuss instantly. The formula is °c = (°f − 32) × 5⁄9 — subtract 32 first, then multiply by 5/9 — 98.6 °F is 37 °C, 212 °F is 100 °C. Everything is computed locally in your browser; nothing is uploaded.
How to convert °F to °C
The exact conversion factor between fahrenheits and celsiuss gives the formula °C = (°F − 32) × 5⁄9. Subtract 32 first, then multiply by 5/9 — 98.6 °F is 37 °C, 212 °F is 100 °C.
For a rough mental estimate, remember that 1 °F = -17.22 °C. To go the other way, see the celsius to fahrenheit converter — it uses the reciprocal factor.
Worked examples
Example: convert 68 °F to °C. Apply the formula — °c = (°f − 32) × 5⁄9 — and you get 20 °C. Reverse-check it by using the celsius to fahrenheit to come back to 68 °F; if you do not land on the original number, a factor was inverted.
Example: convert 212 °F to °C. Apply the formula — °c = (°f − 32) × 5⁄9 — and you get 100 °C. Reverse-check it by using the celsius to fahrenheit to come back to 212 °F; if you do not land on the original number, a factor was inverted.
Where the factor comes from
Celsius and Fahrenheit are not related by a simple factor because their zero points differ: 0 °C is the freezing point of water, while 0 °F was set to the freezing point of a salt solution. The scales meet at −40 degrees (−40 °C = −40 °F), which makes −40 the fastest sanity check in temperature conversion. The Fahrenheit degree is also smaller — exactly 5⁄9 of a Celsius degree — which is why the formula multiplies by 9⁄5 before adding 32.Common mistakes
Adding 32 before multiplying. Order matters: multiply by 9⁄5 first, then add 32. Doing it backwards inflates the result by nearly a factor of two at room temperatures.
Treating °C and K with the same formula. Kelvin has no offset: K = °C + 273.15, no 9⁄5 factor. The formulas on this page apply only to the Celsius–Fahrenheit pair.
Trusting body-temperature folklore. 98.6 °F is a rounded 19th-century average; modern references put normal body temperature closer to 97.5–99 °F depending on the person and the time of day.
Quick mental shortcuts
Mental shortcuts: °C → °F ≈ double and add 30 (20 °C → 70 °F, true value 68); °F → °C ≈ subtract 30 and halve (70 °F → 20 °C). Exact only at −40°, but useful within ±2° for weather.
Common °F to °C conversions
| Fahrenheit (°F) | Celsius (°C) |
|---|---|
| 32 | 0 |
| 68 | 20 |
| 98.6 | 37 |
| 104 | 40 |
| 212 | 100 |
FAQ
How do I convert °F to °C?
°C = (°F − 32) × 5⁄9. Subtract 32 first, then multiply by 5/9 — 98.6 °F is 37 °C, 212 °F is 100 °C.
What is 68 °F in °C?
68 °F equals 20 °C. Use the converter above for any value.
How do I convert °C back to °F?
Use the reverse conversion — see our celsius to fahrenheit converter. The calculator above also shows the reciprocal rate.
Is the °F-to-°C conversion exact?
The formulas are exact mathematical definitions of the scales; everyday readings are rounded to one or two decimals.
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