Sunset Calculator
Calculate the exact sunset time for any location worldwide using date, latitude, longitude, and timezone. Includes atmospheric refraction correction, twilight times, solar noon, and day length.
About This Calculator
The Sunset Calculator computes the exact time of sunset for any location on Earth based on date, latitude, longitude, and timezone. Whether you are a photographer planning golden hour shots, an astronomer scheduling observations, or simply curious about when the Sun will set at your location, this tool provides accurate results using the standard NOAA Solar Calculator algorithm.
The calculation works by first determining the Sun's position in the sky — its declination and right ascension — based on the day of the year and Earth's orbital parameters. Using the observer's latitude and the Sun's declination, the hour angle at sunset is computed. The result is converted to local time by accounting for the observer's longitude and timezone offset. The calculator also provides a corrected sunset time that accounts for atmospheric refraction (which bends sunlight and makes the Sun appear higher than it is, giving us about 6 extra minutes of daylight) and the Sun's apparent diameter.
Four types of dusk are supported: Sunset (Sun at the horizon, 90° from zenith), Civil Twilight (Sun 6° below — enough light for most outdoor activities), Nautical Twilight (Sun 12° below — horizon still visible at sea), and Astronomical Twilight (Sun 18° below — sky fully dark for stargazing).
The calculator correctly handles polar regions: locations above the Arctic Circle or below the Antarctic Circle experience polar day (midnight sun with no sunset) during summer and polar night (no sunrise) during winter.
Frequently Asked Questions
How is the sunset time calculated?
Sunset time is calculated using the Sun's position in the sky based on the Earth's orbit and rotation. The calculator uses the day number, latitude, longitude, and timezone to compute the Sun's declination, right ascension, and hour angle, then converts the result to local time.
What is the difference between uncorrected and corrected sunset times?
The uncorrected sunset time assumes the Sun sets when its center reaches the geometric horizon at 90 degrees from the zenith. The corrected time accounts for atmospheric refraction (which bends sunlight) and the Sun's apparent diameter, using a zenith angle of 90.833 degrees. Refraction gives us approximately 6 extra minutes of visible daylight.
What is the difference between sunset, civil twilight, nautical twilight, and astronomical twilight?
Sunset is when the Sun's upper edge touches the horizon (0 degrees below). Civil twilight ends when the Sun is 6 degrees below the horizon (bright enough for outdoor activities without artificial light). Nautical twilight ends at 12 degrees below (horizon still visible at sea). Astronomical twilight ends at 18 degrees below (sky fully dark for astronomical observations).
Why does sunset time change throughout the year?
Sunset time changes because the Earth's axis is tilted 23.45 degrees relative to its orbital plane. As Earth orbits the Sun, the declination of the Sun varies between +23.45 and -23.45 degrees, causing the Sun's apparent path across the sky to shift. This results in earlier sunsets in winter and later sunsets in summer.
Can there be no sunset at some locations?
Yes, locations near the poles experience polar day (midnight sun) where the Sun never sets for several weeks during summer, and polar night where it never rises during winter. This occurs when the Sun's declination exceeds 90 degrees minus the latitude, making the hour angle calculation impossible.
How accurate is this sunset calculator?
This calculator uses the standard astronomical algorithm with the NOAA Solar Calculator formula. Results are typically accurate to within 1-2 minutes for most locations. Accuracy depends on correct latitude, longitude, and timezone input. The atmospheric refraction correction improves accuracy near the horizon.
What is the solar noon and why does it matter?
Solar noon is the moment when the Sun reaches its highest point in the sky, crossing the local meridian. It is the midpoint between sunrise and sunset. Knowing solar noon helps in calculating day length and understanding the Sun's daily arc. It rarely coincides with 12:00 PM on clocks due to timezone and daylight saving adjustments.