Approximate hours of daylight for a latitude and day of the year.
Using the solar declination for the day and the observer's latitude, the formula estimates how many hours the Sun stays above the horizon. Daylight availability drives energy use, outdoor activities and health-related planning throughout the seasons.
Daylight Hours
Daylight = 2 x acos(-tan(latitude) x tan(declination)) x 24 / 360 degrees
Daylight = 2 x acos(-tan(latitude) x tan(declination)) x 24 / 360 degrees Using the solar declination for the day and the observer's latitude, the formula estimates how many hours the Sun stays above the horizon.
Daylight availability drives energy use, outdoor activities and health-related planning throughout the seasons.
This calculator takes 2 inputs: Latitude, Day of year. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.