Golden Hour Calculator

Outdoor light can change more in the half hour around sunrise or sunset than it does across several midday hours. A low sun travels through more atmosphere and reaches a subject from the side, often producing warmer color, longer shadows, and stronger texture. After the sun drops below the horizon, indirect sky light can keep a scene usable while buildings and street lights become more prominent.

Golden hour and blue hour are practical photography terms rather than fixed astronomical standards. Their appearance depends on cloud, haze, terrain, buildings, and camera choices. Solar altitude gives the terms a repeatable planning definition, but it cannot promise a particular color or exposure.

The window length changes with the angle at which the sun crosses the horizon. Near the equator that crossing is often steep and brief. At higher latitudes it may be much slower, and near the polar circles a chosen altitude can remain above or below the horizon all day.

• Location and date determine the sun's seasonal path.
• UTC offset converts solar time to the local clock and must reflect daylight saving time where it applies.
• Altitude boundaries define which part of twilight counts as golden or blue light.
• Terrain and skyline can hide the geometric horizon and shift the useful field window.

How to Use This Tool:

Start with the exact place and local date of the shoot, then adjust the light definition only when it needs to match another planning method.

1. Choose IP Geolocation, City Search, Browser GPS, or Manual Coordinates. Refine a city result when the viewpoint is far from the mapped centre.
2. Enter the Shoot date and the UTC offset in force at that location on that date. A wrong daylight-saving offset moves every displayed time by an hour.
3. Select the morning, evening, or both windows and set an Arrival buffer that covers access, setup, and exposure checks.
4. Review the Window plan and Shoot brief. Check the ready-by time, the low-sun direction, and any missing-crossing or high-latitude warning before committing to the schedule.

Interpreting Results:

The start and end times mark crossings of the configured solar-altitude boundaries. The ready-by time is the focused golden-window start minus the arrival buffer. Direction is azimuth measured clockwise from true north, so 90 degrees is east, 180 degrees is south, and 270 degrees is west.

Treat every clock value as a planning estimate. Confirm the UTC offset, then check a local forecast, horizon obstructions, access, and safety conditions. A missing crossing means the sun never reaches that configured boundary on the selected date; it does not mean that no usable light exists.

Technical Details:

The calculation uses a NOAA-style fractional-year approximation. Latitude, longitude, day of year, and UTC offset locate solar noon on the local clock. The hour angle for each requested solar altitude then gives its morning and evening crossing.

Formula Core:

For day number d in a year containing N days, the fractional-year angle is evaluated at local noon:

The equation of time E, in minutes, and solar declination δ, in radians, follow these approximations:

With east-positive longitude λ and UTC offset z in hours, local solar noon is:

For latitude φ and requested altitude a, the crossing hour angle H is converted to minutes at four minutes per degree. Morning uses subtraction and evening uses addition.

Rule Core:

The default boundaries are planning choices. Their allowed ranges make the band definitions explicit and prevent the blue outer edge from crossing the blue-to-golden handoff.

Internal calculations retain fractional minutes and degrees. Clock times and durations are displayed to the nearest minute, while direction is displayed to the nearest degree. Dates are accepted from 1901 through 2099, latitude from −90° to +90°, longitude from −180° to +180°, and UTC offset from −12 to +14 hours.

Limitations, Privacy, and Accuracy Notes:

Solar geometry describes an unobstructed mathematical horizon. It does not model elevation, mountains, buildings, cloud, haze, refraction changes, or the exact look of a scene.

• IP location can point to an internet provider, VPN, proxy, or carrier gateway rather than the camera position.
• City searches send the search text to OpenStreetMap's Nominatim service. IP lookup contacts an external geolocation provider, and Browser GPS uses the browser's permission-controlled location service.
• Manual coordinates avoid those optional location lookups and are the best choice when the viewpoint is already known.
• At high latitudes, a configured altitude may not be crossed. Review the warning rather than substituting a fabricated time.

Worked Examples:

References:

• General Solar Position Calculations, NOAA Global Monitoring Laboratory.
• Nominatim Usage Policy, OpenStreetMap Foundation.
• Geolocation API, MDN Web Docs.