The conversion

77°F = 25°C

°C = (°F − 32) × 5/9, so (77 − 32) × 5/9 = 25.

As an outdoor air temperature, 77 °F sits in the warm 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 to Celsius either side of 77 °F.
FahrenheitCelsius
72 °F22.22 °C
73 °F22.78 °C
74 °F23.33 °C
75 °F23.89 °C
76 °F24.44 °C
77 °F25 °C
78 °F25.56 °C
79 °F26.11 °C
80 °F26.67 °C
81 °F27.22 °C
82 °F27.78 °C

The other direction

25 °C converts back to 77 °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.