How we calculate sunrise and sunset times

Updated October 6, 2026

Every time on Sunrise-Sunset.org is calculated for the coordinates of each place and for the exact date, and shown to the second. This page explains what each time means, how we work it out, and the conventions behind our tables, so you know exactly what you are looking at.

Sunrise and sunset

Sunrise is the moment the top edge of the Sun appears above the horizon, and sunset the moment it disappears. Not the center of the Sun: the very first and very last glimpse of it.

Because the atmosphere bends sunlight, the Sun is still visible for a few minutes after it has geometrically gone below the horizon. We use the international standard: at sunrise and sunset the Sun's center is 0.833 degrees below the horizon (0.567 degrees for refraction plus 0.266 degrees for the Sun's radius).

This is the same definition used by the U.S. Naval Observatory, NOAA and national almanacs, so our times can be compared with theirs directly.

Twilight, first light and last light

Twilight is the time when the Sun is below the horizon but the sky is still lit. It is measured by how far below the horizon the Sun's center is, and comes in three stages:

• Civil twilight (0.833° to 6°)Bright enough for most outdoor activities without artificial light. Its start and end are what our tables call first light and last light.
• Nautical twilight (6° to 12°)The horizon at sea is still visible and the brightest stars appear. Sailors used it to take star sightings.
• Astronomical twilight (12° to 18°)The sky looks dark to the eye, but faint stars and galaxies are still washed out. Below 18° it is fully night.

Twilight generally lasts longer the further you are from the equator, especially in summer. In Quito, on the equator, civil twilight is over in about 20 minutes and it is fully dark a little over an hour after sunset; in Reykjavík civil twilight alone can last for hours, and in summer it may never get fully dark.

Everything else in the table

• Solar noon is the moment the Sun crosses your local meridian, the north-south line over your head, which is usually its highest point of the day. It is rarely exactly 12:00, because of the place's longitude within its time zone, daylight saving time and the equation of time.
• Day length is the time from sunrise to sunset. Day length variation is how much longer or shorter the day is than the day before: in autumn in the Northern Hemisphere it shrinks by a couple of minutes a day.
• Max sun altitude is the Sun's height above the horizon at solar noon, in degrees: low in winter, high in summer.
• Night length is the time from sunset to the next sunrise.
• Moon phase shows the phase and the illuminated share of the Moon's disk for that day.

Choose which columns to show with the Customize table button above any monthly table, for example New York in November 2026. For a printable month, use the sunrise and sunset calendar.

How the times are computed

We compute the position of the Sun with the solar position algorithm published by NOAA (the U.S. National Oceanic and Atmospheric Administration), which is based on Jean Meeus's Astronomical Algorithms. For every place and every date, we search for the exact moments when the Sun crosses each altitude: the horizon for sunrise and sunset, and 6, 12 and 18 degrees below it for the three twilights. Solar noon is the moment of the Sun's highest point.

We check our results against the high-precision ephemerides of NASA's Jet Propulsion Laboratory, for places from the equator to the Arctic and for dates all through the year.

The same engine powers our free sunrise and sunset API, so for the same place and date the website and the API give the same times.

Time zones and daylight saving time

All times are shown in the local time of the place, not in your own time zone: if you look up London from Denver, you get London time. We use the IANA time zone database (also called the tz or Olson database), the same one used by computers and phones, which records every time zone and daylight saving rule, past and future.

Days when the clocks change are marked in our tables, so a sudden one-hour jump in sunrise or sunset is never a surprise. See the first Sunday of November 2026 in New York.

Countries change their clock rules more often than you might think, sometimes with only a few weeks' notice. We put a lot of care into keeping every time zone in the world up to date, and when a rule changes we update our data as soon as it is official. Our readers are part of this too: every message about a clock change or a time that looks off is checked against the official rules, and if something needs fixing, we fix it.

Conventions we follow

• Each event belongs to the local calendar date on which it happens, in the time zone in force in that place on that day.
• Times are shown to the second, and durations in hours, minutes and seconds.
• Times use the 12-hour clock, as in 7:44:05 pm, the format usual for readers of this site.

Places and coordinates

Each place has a single representative point, usually its town center. Its latitude, longitude and time zone are shown on the place's page. Every page also links to nearby places, so you can check the one closest to you.

In big cities the distance from that point matters. At mid-latitudes, sunrise and sunset shift by about a minute for every 20 km you move east or west, so across a metropolitan area like London the two ends can be two or three minutes apart, and in a sprawling one like Los Angeles even more. If you are far from the center, look up your own neighborhood or town, or search your coordinates.

When a place is in the wrong spot or has the wrong name, it is usually one of our users who spots it first, and we fix it.

Searching by coordinates works too: type 40.7128, -74.0060 (or degrees, minutes and seconds) in the search box and we calculate the times for that exact point.

Your local view

Our times are for a flat horizon at sea level, the standard reference used by every almanac. What you see on a given evening can differ by a minute or two, and by much more where hills or buildings block the horizon:

• Mountains, hills or buildings on the horizon hide the Sun earlier at sunset and reveal it later at sunrise. In a valley like Kathmandu, the Sun can disappear behind the hills well before the official sunset.
• From high up, on a mountain or a tall building, you see a little further over the horizon, so sunrise comes slightly earlier and sunset slightly later.
• Unusual air temperature near the ground changes how much the light bends, which can move the moment by a minute or so.

Sources

• NOAA Global Monitoring Laboratory, Solar Calculation Details.
• Jean Meeus, Astronomical Algorithms, 2nd edition, Willmann-Bell, 1998.
• U.S. Naval Observatory, definitions of sunrise, sunset and twilight.
• NASA Jet Propulsion Laboratory, planetary and lunar ephemerides (for testing).
• IANA Time Zone Database.