What the Sunrise and Sunset Calculator does
Enter a latitude, longitude and date and this calculator gives sunrise, sunset, solar noon, day length, the morning and evening golden hours and all three twilights - civil, nautical and astronomical - in the local time zone you choose, plus a table for every day of the month and a chart of day length through the year.
It uses the solar equations published by NOAA's Global Monitoring Laboratory (after Jean Meeus), computed in your browser. Nothing is looked up online, so it works for any place and any date, including places with midnight sun or polar night.
How to use it
- Paste the place's coordinates. The easiest source is a map app: long-press or right-click a point and copy its latitude and longitude. Decimal degrees, DMS, UTM and MGRS are all accepted.
- Pick the date and the time zone of the place. The zone matters because daylight saving shifts clock times by an hour on the dates that zone changes.
- Read sunrise and sunset in the headline, then the twilight table for first light and last light. Golden hour appears as a morning and an evening window.
- Scroll to the month table for planning a trip or a shoot, and download it as CSV. The chart shows how day length changes through the year at that latitude.
Reading the results
Sunrise and sunset are the moments the top edge of the Sun's disc touches a flat, clear horizon. The calculation puts the Sun's centre 0.833° below the horizon to allow for atmospheric refraction (about 34 arcminutes) and the Sun's radius (about 16 arcminutes).
Civil twilight (Sun down to 6° below the horizon) is when there is still enough light for most outdoor work without lamps. Nautical twilight (to 12°) is when sailors could still see the horizon to take star sights. Astronomical twilight (to 18°) ends when the sky is fully dark for faint objects.
Golden hour has no official definition. Here it is the time the Sun is between 4° below and 6° above the horizon - a photographers' convention, not a standard. Near the equator it is short; at high latitudes in summer it can last for hours.
When the table says an event does not happen, the Sun simply never reaches that angle that day - for example no astronomical darkness in London around midsummer, or no sunrise at all during polar night.
Worked example: the June solstice at the Royal Observatory, Greenwich
At 51.4779° N, 0.0015° W on 21 June 2025, the Sun's declination is about +23.44°. Solar noon comes at about 13:02 BST (12:02 UTC): the equation of time is about -1.9 minutes that day, so the Sun crosses the meridian a couple of minutes after 12:00 UTC.
The noon Sun stands 90 - 51.48 + 23.44 = 61.96° above the horizon. Sunrise works out at 04:43 BST and sunset at 21:21 BST, a day length of about 16 hours 38 minutes - the same figures the UK almanac tables publish.
Civil dusk follows at about 22:09 BST, and astronomical twilight never ends: the Sun only reaches about 15° below the horizon at midnight, so London has no truly dark sky around midsummer.
Formulas and scoring rules
- Hour angle at an event
cos H = cos z / (cos lat x cos dec) - tan lat x tan decz = 90.833° for sunrise and sunset, 96° civil, 102° nautical, 108° astronomical; 84° and 94° bound golden hour. No solution means the event does not happen that day.- Solar noon (UTC minutes)
720 - 4 x longitude - equation of timeLongitude in degrees, east positive; the equation of time is in minutes.- Sunrise and sunset
solar noon -/+ 4 x H (minutes)Each event is refined with the Sun's position at that moment rather than at noon.- Day length
sunset - sunrise24 h in midnight sun, 0 in polar night.
Limitations: what the result does not prove
- Times assume a flat, sea-level horizon. Hills or buildings to the east make the sun appear later; standing on a mountain makes it appear earlier and set later.
- Refraction varies with temperature and pressure. Near the horizon it can move the real sunrise by a minute or two, and by much more in the polar regions where the Sun skims the horizon.
- Accuracy is about one minute between latitudes 72° north and south, the limit NOAA states for these equations. Beyond that, treat times as approximate.
- The tool does not look up addresses or time zones. Choose the zone yourself; a wrong zone shifts every time by the offset difference.
Privacy: where your data goes
Everything you paste, type or drop is processed in this browser tab. It is not uploaded, logged, stored or sent to analytics. Session recording and tag-manager scripts are switched off on this page.
Standards and sources
- NOAA Global Monitoring Laboratory - solar calculation details - checked 19 Sep 2026
- NOAA - General solar position calculations
- US Naval Observatory - Rise, set and twilight definitions
Frequently asked questions
Why is the earliest sunrise not on the longest day of the year?
Because solar noon itself drifts through the year with the equation of time. Around the June solstice solar noon is getting later each day, so in the UK the earliest sunrise comes a few days before the solstice and the latest sunset a few days after it. The month table shows this clearly.
What is the difference between civil, nautical and astronomical twilight?
They are defined by how far the Sun is below the horizon: 6° for civil, 12° for nautical and 18° for astronomical. Civil twilight is bright enough to read outside, nautical twilight still shows the horizon at sea, and after astronomical twilight the sky is as dark as it gets.
When is golden hour for photography?
It is conventionally the time the Sun is low - here between 4° below and 6° above the horizon - so the light is warm and soft. There is no official standard, and clouds or terrain matter more than the exact minute, but the windows shown are a reliable planning guide.
Why does the calculator say the sun never sets?
North of the Arctic Circle around the June solstice (and south of the Antarctic Circle in December), the Sun stays above the horizon for the whole day. The opposite happens in winter: polar night, with no sunrise at all. The tool reports both instead of inventing a time.
Does sunrise time depend on altitude?
Yes. From higher ground you see past the curve of the Earth: the horizon dips by about 1.76 arcminutes times the square root of your height in metres, so at 300 m it is half a degree lower and, at mid-latitudes, the Sun rises roughly 3 minutes earlier and sets 3 minutes later. This calculator uses a sea-level horizon, so a hilltop observer will see slightly longer days.
How accurate are these sunrise and sunset times?
The astronomy is good to about a minute at mid-latitudes. The bigger uncertainty is the atmosphere and your horizon: unusual refraction, haze, hills or tall buildings can shift what you actually see by a few minutes. Treat times as planning figures, not stopwatch readings.
Last reviewed by the A2Z.Tools team against the sources listed above.
