Sunrise and Sunset Calculator: A Guide for Photographers, Travelers, and Planners
A sunrise/sunset calculator gives you precise timing for golden hour, blue hour, and full daylight in any city. Here is how it works, what to use it for, and why the calculation is more interesting than you might think.
What a Sunrise/Sunset Calculator Tells You
A sunrise/sunset calculator gives you the precise local time of three things: when the sun rises (its top edge crosses the horizon at dawn), when it sets (its top edge crosses the horizon at dusk), and the total daylight duration for that day. A good calculator also includes twilight times — civil, nautical, and astronomical — which mark the gradual transition between day and night. For any city, on any date, you can know these times to within about a minute. The calculation is based on the sun's position in the sky relative to your specific latitude and longitude, with a small correction for atmospheric refraction.
Why Photographers Need One
For photographers, light matters more than equipment. The two most important moments of the day for photography are golden hour (the hour after sunrise and before sunset, when the light is warm and low-angle) and blue hour (the hour before sunrise and after sunset, when the sky is deep blue). These windows are short and they shift by a few minutes every day. A sunrise/sunset calculator tells you exactly when they begin and end for your location, so you can plan your shoot. Showing up 15 minutes late to golden hour can cost you the shot entirely.
Golden Hour and Blue Hour Defined
Golden hour starts roughly when the sun is between 6 degrees above and 6 degrees below the horizon. Light during this window is soft, warm, low-angle, and creates long shadows that flatter most subjects. Blue hour is the period when the sun is between 4 and 8 degrees below the horizon — the sky takes on a deep, saturated blue, and city lights have come on but ambient light is still bright enough to capture detail. Most landscape and architectural photographers structure entire shoots around these two windows. A good calculator gives you the start and end of each, not just sunrise and sunset.
Civil, Nautical, and Astronomical Twilight
Twilight is the gradual transition between full daylight and full darkness, and it has three official phases. Civil twilight (sun 0–6 degrees below horizon) is when there is enough light for outdoor activities without artificial illumination. Nautical twilight (6–12 degrees below) is when the horizon is still distinguishable for navigation. Astronomical twilight (12–18 degrees below) is when the sky is dark enough for sensitive astronomy. After astronomical twilight ends, you have full night. A good calculator shows all three phases for both dawn and dusk, useful for astronomers, sailors, and anyone planning night activities.
Travelers: Plan Your Days Around the Sun
When you travel to a new city, knowing local sunrise and sunset is more useful than you might think. It helps you plan outdoor sightseeing (beaches, scenic viewpoints, hiking trails are all daylight-dependent). It tells you whether a planned outdoor activity will end in light or darkness. It helps with jet lag adjustment — getting morning sunlight is the fastest way to reset your circadian rhythm to the new zone. For high-latitude destinations in summer or winter, the sunrise and sunset times can be radically different from what you are used to (Tromsø, Norway: 24-hour daylight in June, 24-hour darkness in December).
Astronomers and Stargazers: Plan for Darkness
For amateur astronomers, the relevant question is "when is the sky dark enough?" A standard sunrise/sunset answer is not enough; you want astronomical twilight end (after which the sky is full-dark) and astronomical twilight start (after which it begins to brighten). For deep-sky observation, plan to be at your viewing site after astronomical twilight ends. For meteor showers, the best viewing is usually after midnight in any case, but the duration of usable darkness varies by latitude and season — at high latitudes in summer, full astronomical darkness may not occur at all.
Religious and Cultural Observances
Many religious observances depend on sunrise and sunset times: Islamic prayer times, Jewish Shabbat start and end, Hindu auspicious moments, Bahá'í fasting hours during Ridvan. A sunrise/sunset calculator gives the precise local timing needed for these observances. Some major religious calendars include the relevant times directly, but a calculator is useful for travelers, expats, or for any unusual location where the calendar is not provided.
Outdoor Sports and Activities
If you play outdoor sports — golf, tennis, soccer — knowing exactly when sunset is helps you plan whether a game can finish in daylight. The same applies to hikers, runners, cyclists, and anyone whose activity becomes dangerous after dark. Trail runners commonly use sunrise/sunset times to plan turnaround points; a 4-hour out-and-back hike that starts at 3 PM in winter is a recipe for finishing in the dark, which is much riskier than finishing in daylight.
Energy and Solar Panel Owners
For solar panel owners, the most productive hours are within ~2 hours of solar noon, when the sun is highest. Solar generation begins shortly after sunrise and ends shortly before sunset. Knowing the daylight window for the current season helps you plan electricity usage — running heavy loads (laundry, dishwasher, EV charging) during solar production hours maximizes self-consumption. Sunrise/sunset shifts dramatically through the year, so summer and winter strategies differ.
How the Calculation Actually Works
The calculation uses spherical astronomy. Inputs: your latitude, longitude, and the current date. The algorithm computes the sun's declination (its angle north or south of the celestial equator) for that date. From declination and your latitude, it computes the hour angle at which the sun crosses the horizon. Atmospheric refraction is approximated using a standard atmosphere model (the sun's position is bent by about 34 arcminutes near the horizon, so it appears to set about 2 minutes after it geometrically does). The result is accurate to about a minute under typical atmospheric conditions. Major variations in atmospheric pressure or temperature can shift the time by another minute or so, but for most purposes the calculator is plenty accurate.
Why Times Shift Throughout the Year
Sunrise and sunset times shift continuously throughout the year because of the Earth's axial tilt. As the Earth orbits the sun, the angle of sunlight relative to your latitude changes. In summer, the sun rises earlier and sets later, giving long days; in winter, it rises later and sets earlier, giving short days. The change is smooth — usually about 1–3 minutes per day in most temperate latitudes — but it adds up. A photographer in New York who is used to a 5:30 AM sunrise in June will have a 7:15 AM sunrise in December, an hour and 45 minutes different.
Use Clockzilla's Sunrise/Sunset Tool
Clockzilla calculates sunrise, sunset, and twilight times for any of 150,000+ cities worldwide using the NOAA Solar Calculator algorithm. Open any city page (e.g., clockzilla.io/time/london) and you will see today's sunrise time, sunset time, and total daylight duration alongside the current local time. The values update automatically as you cross dates, accounting for the seasonal shift. Free, no signup, accurate to within about a minute under typical conditions — accurate enough for everything we have discussed in this article.
About this article
This article was written and edited by the Clockzilla editorial team. We review every published article at least once per year and update facts when underlying data changes. The most recent review was April 2026.
Read about our editorial and measurement methodology, or contact us if you spot an error.
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