-18°C in °F
-18°C is -0.4°F. To convert Celsius to Fahrenheit, multiply by 1.8, then add 32.
Formula from NIST.
Show the workings
| Step | Sum | Answer |
|---|---|---|
| Multiply by 1.8 | -18 × 1.8 | -32.4 |
| Add 32 | -32.4 + 32 | -0.4 °F |
Where the figures come from
- Fahrenheit reading at the freezing point used in the conversion: 32 °F. Source: NIST Guide to the SI, Appendix B.9: factors for units listed by kind of quantity. Checked 14 November 2026.
- Fahrenheit degrees in one Celsius degree: 1.8. Source: NIST Guide to the SI, Appendix B.9: factors for units listed by kind of quantity. Checked 14 November 2026.
Nearby temperatures
How to convert Celsius to Fahrenheit
The US National Institute of Standards and Technology gives the conversion as °C = (°F − 32) ÷ 1.8. So to go from °C to °F, multiply by 1.8, then add 32. For example, -18°C is -04°F.. See NIST's table.
The two scales meet at −40, where −40°C and −40°F are the same temperature.