Convert Fahrenheit to Celsius
To convert degrees Fahrenheit to degrees Celsius, use °C = °F × 0.5555555556 − 17.77777778: 68 °F = 20 °C, and 0 °F = -17.77777778 °C.
1 °F = -17.22222222 °C
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk Fahrenheit to Celsius converter to paste a column from Excel.
How to Convert Fahrenheit to Celsius
- 1 °F = -17.22222222 °C
- 1 °C = 33.8 °F
- Example: convert 68 °F to °C: 68 °F = (68 × 0.5555555556 − 17.77777778) °C = 20 °C
Formula
°C = °F × 0.5555555555556 − 17.77777777778
Derivation from SI units:
- T(K) = (t(°F) + 459.67) × 5/9; t(°F) = t(°C) × 9/5 + 32
- T(K) = t(°C) + 273.15 (exact, by definition)
- Solving for °C: °C = °F × 0.5555555555556 − 17.77777777778
Both units are defined exactly, so the factor is exact. Fahrenheit definition: degree Fahrenheit; Celsius definition: degree Celsius.
Worked examples
- A recipe oven setting of 350 °F is 176.6666667 °C.
350 × 0.5555555556 − 17.77777778 = 176.6666667 °C - The traditional normal body temperature of 98.6 °F is 37 °C.
98.6 × 0.5555555556 − 17.77777778 = 37 °C
Fahrenheit to Celsius conversion table
| Fahrenheit (°F) | Celsius (°C) |
|---|---|
| -459.67 °F | -273.15 °C |
| -40 °F | -40 °C |
| -20 °F | -28.88888889 °C |
| 0 °F | -17.77777778 °C |
| 10 °F | -12.22222222 °C |
| 20 °F | -6.666666667 °C |
| 32 °F | 0 °C |
| 40 °F | 4.444444444 °C |
| 50 °F | 10 °C |
| 60 °F | 15.55555556 °C |
| 65 °F | 18.33333333 °C |
| 68 °F | 20 °C |
| 70 °F | 21.11111111 °C |
| 72 °F | 22.22222222 °C |
| 75 °F | 23.88888889 °C |
| 80 °F | 26.66666667 °C |
| 90 °F | 32.22222222 °C |
| 98.6 °F | 37 °C |
| 100 °F | 37.77777778 °C |
| 120 °F | 48.88888889 °C |
| 150 °F | 65.55555556 °C |
| 180 °F | 82.22222222 °C |
| 212 °F | 100 °C |
| 250 °F | 121.1111111 °C |
| 300 °F | 148.8888889 °C |
| 350 °F | 176.6666667 °C |
| 400 °F | 204.4444444 °C |
| 450 °F | 232.2222222 °C |
| 500 °F | 260 °C |
Where it's used
US recipes, weather reports and thermostats use Fahrenheit. Subtracting 32 and multiplying by 5/9 gives Celsius, the scale used in science and in most other countries.
Fahrenheit to other temperature units
| Conversion | 1 °F equals |
|---|---|
| Fahrenheit to Celsius | -17.22222222 °C |
| Fahrenheit to Kelvin | 255.9277778 K |
| Fahrenheit to Rankine | 460.67 °R |
Frequently asked questions
What is the formula for °F to °C?
°C = (°F − 32) × 5/9. For example, 72 °F = 22.22 °C.
Is 100 °F a fever?
100 °F is 37.78 °C, slightly above normal; a common fever threshold is 100.4 °F (38 °C).
What is the formula for degrees Fahrenheit to degrees Celsius?
°C = °F × 0.5555555556 − 17.77777778. For example, 68 °F = 20 °C.
What is 0 °F in °C?
0 °F = -17.77777778 °C, and 100 °F = 37.77777778 °C.
How do I convert a temperature difference from °F to °C?
For a difference (an interval), ignore the offset and multiply by 0.5555555556 only: a change of 10 °F is a change of 5.555555556 °C.
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "degree Fahrenheit (°F)".
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Section 2.3.1 and Table 4, degree Celsius.
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert Fahrenheit to Celsius. Retrieved October 17, 2026, from https://scientificconverters.com/temperature/fahrenheit-to-celsius/
IEEE
Scientific Converters, "Convert Fahrenheit to Celsius," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/temperature/fahrenheit-to-celsius/