Day Length Calculator

Day length is calculated using the NOAA solar algorithm, which computes the Sun's position based on your latitude, longitude, and the date. The algorithm accounts for the Earth's axial tilt and orbital position to determine the exact times of sunrise and sunset, and the difference gives you the length of daylight.

Day length changes because Earth's rotational axis is tilted approximately 23.5° relative to its orbit around the Sun. During summer in your hemisphere, your location tilts toward the Sun, producing longer days. In winter, it tilts away, resulting in shorter days. At the equinoxes (around March 20 and September 22), day and night are roughly equal everywhere on Earth.

Solar noon is the moment when the Sun reaches its highest point in the sky and is due south (in the Northern Hemisphere) or due north (in the Southern Hemisphere). It is the midpoint between sunrise and sunset and represents the peak of solar energy for the day. Solar noon does not necessarily coincide with 12:00 PM on your clock.

You can find your latitude and longitude by searching your city name on Google Maps, then right-clicking on your location to see the coordinates. Alternatively, search 'my coordinates' in Google or use your smartphone's location settings. Latitude values range from -90° (South Pole) to +90° (North Pole), and longitude values range from -180° to +180°.

The equation of time describes the difference between apparent solar time (the Sun's actual position) and mean solar time (clock time). It arises because Earth's orbit is elliptical and its axis is tilted. This calculator incorporates the equation of time into its NOAA-based algorithm for more accurate sunrise and sunset calculations.

Yes. This calculator does not automatically detect DST for your location. If your region is currently observing daylight saving time, set the DST toggle to 'Yes (+1 hour)'. The underlying day length calculation is unaffected by DST — only the displayed clock times for sunrise and sunset shift by one hour.

Minor differences can occur because weather apps typically correct for atmospheric refraction (the bending of sunlight as it passes through the atmosphere) and use your exact GPS coordinates. This calculator uses the standard NOAA algorithm with a 0.833° refraction correction at the horizon, which matches most astronomical definitions of sunrise and sunset.

Near the poles, extreme conditions occur during summer and winter. In summer, locations above the Arctic Circle (latitude > 66.5°N) experience midnight sun — the Sun never fully sets. In winter, they experience polar night — the Sun never rises. This calculator handles these edge cases and will indicate when there is no sunrise or no sunset for the selected date and location.