Sunrise Sunset Calculator

Enter a latitude, a longitude, a date, and a timezone, and you get the local clock times of sunrise, sunset, and solar noon, plus the length of daylight. It also reports the solar declination and the equation of time for that day, the two quantities the sunrise math depends on. Everything runs in your browser, so no location data leaves your device.

It uses the NOAA solar-position algorithm, which follows Jean Meeus's Astronomical Algorithms. The steps compute the Sun's mean longitude and anomaly, the equation of center, the apparent longitude, the obliquity of the ecliptic, the solar declination, and the equation of time. From the declination and your latitude it solves for the sunrise hour angle, then converts that angle into clock times around solar noon at 4 minutes of time per degree.

Two effects push sunrise earlier and sunset later than pure geometry predicts. The Sun is treated as risen when its upper edge touches the horizon, which is about 0.27 degrees before its center arrives, and atmospheric refraction bends the light by roughly another 0.57 degrees near the horizon. The calculator bundles these into the standard 90.833 degree zenith angle, which adds several minutes of daylight, so even on an equinox the day runs to about 12 hours and 7 minutes.

Near the solstices, places above the polar circles can have the Sun stay up all day or never clear the horizon. When that happens the sunrise equation has no solution, and the calculator reports either polar day (24 hours of daylight, the midnight sun) or polar night (zero hours), while still showing solar noon. This is normal behavior at high latitudes, not an error.

The NOAA algorithm is accurate to about a minute for most locations and dates, which is why results are shown to the nearest minute. The model assumes a flat sea-level horizon and average refraction, so real sunrise and sunset can move a minute or two with elevation, nearby mountains or buildings, and unusual weather. Make sure your longitude sign is correct, since east is positive and west is negative.