The conversion
104°F = 40°C
°C = (°F − 32) × 5/9, so (104 − 32) × 5/9 = 40.
As an outdoor air temperature, 104 °F sits in the hot 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.
| Fahrenheit | Celsius |
|---|---|
| 99 °F | 37.22 °C |
| 100 °F | 37.78 °C |
| 101 °F | 38.33 °C |
| 102 °F | 38.89 °C |
| 103 °F | 39.44 °C |
| 104 °F | 40 °C |
| 105 °F | 40.56 °C |
| 106 °F | 41.11 °C |
| 107 °F | 41.67 °C |
| 108 °F | 42.22 °C |
| 109 °F | 42.78 °C |
The other direction
40 °C converts back to 104 °F, which is the same relationship read the other way. Going from Celsius to Fahrenheit, multiply by 9/5 first and then add 32. Adding first is the usual mistake.
The full converter handles any value, in either direction, including kelvin, and shows the formula as it works.