To convert Fahrenheit to Celsius, subtract 32 and divide by 1.8: °C = (°F − 32) / 1.8. To go the other way, °F = °C × 1.8 + 32. Kelvin is Celsius plus 273.15, and Rankine is Kelvin × 1.8. These are the exact conversions NIST publishes. So 350 °F is 176.67 °C (an oven at "180 °C" in a European recipe), and 20 °C is 68 °F.
Enter a temperature in any scale and this converter shows all four at once, and flags values below absolute zero.
How to use the temperature converter
- Enter the temperature. Negative values are allowed.
- Pick the scale it is in.
- Read Celsius, Fahrenheit, Kelvin and Rankine. Results are rounded to 0.01 degree.
Formula
One Celsius degree is the same size as one kelvin, and 1.8 times the size of a Fahrenheit degree. A change of 10 °C is therefore a change of 18 °F; don't add 32 when converting a difference.
Worked example
Convert 350 °F (a common oven setting) and 37 °C.
- 350 − 32 = 318; 318 / 1.8 = 176.67 °C; + 273.15 = 449.82 K.
- 37 × 1.8 = 66.6; + 32 = 98.6 °F.
- −40 °C = −40 °F, the one point where both scales agree.
Oven temperatures
| °F | °C (exact) | Typical recipe °C |
|---|---|---|
| 300 | 148.9 | 150 |
| 325 | 162.8 | 160–165 |
| 350 | 176.7 | 175–180 |
| 375 | 190.6 | 190 |
| 400 | 204.4 | 200–205 |
| 425 | 218.3 | 220 |
| 450 | 232.2 | 230 |
The "typical" column is the rounded value you will see in recipes, not a standard. Fan (convection) ovens are often set lower than conventional ones; follow the recipe. For cups, spoons and grams, use the cooking measurement converter.
Reference points
| Point | °C | °F | K |
|---|---|---|---|
| Absolute zero | −273.15 | −459.67 | 0 |
| Water freezes (1 atm) | 0 | 32 | 273.15 |
| Room temperature (approx.) | 20 | 68 | 293.15 |
| Body temperature (approx.) | 37 | 98.6 | 310.15 |
| Water boils (1 atm) | 100 | 212 | 373.15 |
Quick mental estimates
For weather-type temperatures you can estimate quickly:
- °C → °F: double it and add 30. 20 °C ≈ 70 °F (exact: 68 °F). The error grows as you move away from about 10 °C.
- °F → °C: subtract 30 and halve it. 80 °F ≈ 25 °C (exact: 26.7 °C).
For cooking, medicine or science, use the exact formula; the shortcut can be several degrees off at oven temperatures (350 °F estimates to 160 °C, but the exact value is 176.7 °C).
Converting a temperature change
A temperature difference converts without the 32-degree offset, because the offset cancels out. A rise of 5 °C is a rise of 9 °F (5 × 1.8), not 41 °F. Likewise, a thermostat setback of 8 °F is 4.4 °C. Kelvin and Celsius differences are identical (a change of 1 °C = a change of 1 K), and a Rankine difference equals a Fahrenheit difference.
This matters when reading forecasts ("10 degrees colder tomorrow") or scaling a recipe's "reduce the temperature by 25 °F" for a convection oven: that is a reduction of about 14 °C.
Caveats and assumptions
- Results are rounded to two decimals.
- To convert a temperature difference (not a reading), multiply or divide by 1.8 without the 32 offset.
Frequently asked questions
How do I convert Fahrenheit to Celsius?
Subtract 32, then divide by 1.8 (or multiply by 5/9). 72 °F = 22.22 °C.
How do I convert Celsius to Fahrenheit?
Multiply by 1.8 (9/5), then add 32. 25 °C = 77 °F.
What is 350 °F in Celsius?
176.67 °C; recipes usually round it to 175 or 180 °C.
At what temperature are Fahrenheit and Celsius equal?
−40 degrees.
How do I convert Celsius to Kelvin?
Add 273.15. 25 °C = 298.15 K. Kelvin is written without a degree sign.
What is 0 °F in Celsius?
−17.78 °C.
What is 100 °F in Celsius?
37.78 °C.
What is 20 °C in Fahrenheit?
68 °F (20 × 1.8 + 32).
Sources
- NIST — SI Units: Temperature — exact Fahrenheit, Celsius and Kelvin conversion formulas
- NIST SP 811 Appendix B.9 — Conversion factors — degree Rankine and Fahrenheit relationships
This calculator gives estimates for planning and education. Check measurements, local codes, supplier specs and your school's official policy before relying on a result. See our disclaimer and how we build and check calculators.