The conversion
15°C = 59°F
°F = (°C × 9/5) + 32, so (15 × 9/5) + 32 = 59.
As an outdoor air temperature, 15 °C sits in the cool band. The other scale is on the dial beside it in the app, so a reading like this needs no conversion at all.
Convert something else
68°F
The range either side
Neighbouring values, for when the number you actually wanted was a degree or two away.
| Celsius | Fahrenheit |
|---|---|
| 10 °C | 50 °F |
| 11 °C | 51.8 °F |
| 12 °C | 53.6 °F |
| 13 °C | 55.4 °F |
| 14 °C | 57.2 °F |
| 15 °C | 59 °F |
| 16 °C | 60.8 °F |
| 17 °C | 62.6 °F |
| 18 °C | 64.4 °F |
| 19 °C | 66.2 °F |
| 20 °C | 68 °F |
The other direction
59 °F converts back to 15 °C, which is the same relationship read the other way. Going from Fahrenheit to Celsius, subtract 32 first and then multiply by 5/9 — doing it in the other order is the usual mistake and produces a plausible-looking wrong answer.
The full converter handles any value, in either direction, including kelvin, and shows the formula as it works.