How to convert fahrenheit to celsius
Useful for weather, cooking, health context, and converting US readings to metric conventions. Temperature requires both a scale ratio and a zero-point offset, applied in the correct order.
°C = (°F − 32) × 5/9
Worked example: 77 °F = 25 °C.
Fahrenheit to Celsius reference table
| °F | °C |
|---|---|
| -40 | -40 |
| 32 | 0 |
| 68 | 20 |
| 98.6 | 37 |
| 212 | 100 |
Absolute zero
CalcOS rejects thermodynamic temperatures below 0 K: −273.15 °C or −459.67 °F. This physical boundary is enforced regardless of the selected display scale.
Temperature versus temperature difference
The offsets in the formulas above apply to absolute readings. For intervals, a change of 1 °C equals 1 K, and a change of 1 °F equals 5/9 K; the +32 offset is not applied.
Related temperature conversion
Sources: BIPM SI Brochure and NIST Handbook 44, Appendix C. See the complete Temperature Converter guide.