-9°C in Fahrenheit
The exact conversion, the formula, and a mental shortcut that is close enough for weather.
The formula
Multiply by 9/5 and add 32.
(-9 × 9 ÷ 5) + 32 = -16.2 + 32 = 15.8 °F
For weather, a shortcut that needs no calculator is to double the Celsius and add 30: -9 × 2 + 30 = 12, against an exact 15.8. It drifts by about 2 °F per 10 °C, which is fine for deciding what to wear and useless for cooking.
What this temperature feels like
Severely cold — well below freezing, with a real risk of ice underfoot and frozen pipes.
Nearby temperatures
| Celsius | Fahrenheit | Kelvin |
|---|---|---|
| -10 °C | 14 °F | 263.15 K |
| -8 °C | 17.6 °F | 265.15 K |
| -7 °C | 19.4 °F | 266.15 K |
| -6 °C | 21.2 °F | 267.15 K |
| -5 °C | 23 °F | 268.15 K |
| -4 °C | 24.8 °F | 269.15 K |
Frequently asked questions
What is -9°C in Fahrenheit?
15.8°F. Multiply the Celsius figure by 9/5 and add 32.
What is the formula?
°F = (°C × 9/5) + 32. To go the other way, °C = (°F − 32) × 5/9.
At what temperature are the two scales equal?
−40. That is the single point where Celsius and Fahrenheit give the same number, which makes it a handy check on any conversion you do by hand.
Nearby values
Last reviewed September 5, 2026.