Blue hour calculator
Enter a date and location to see the morning and evening blue hour windows, the start of civil twilight, and sunrise and sunset. Everything runs in your browser with the same NOAA-style solar maths as the golden hour tool.
Date & location
North positive (e.g. New Delhi 28.6°N).
East positive (e.g. New Delhi 77.2°E).
Location permission is only requested after you click the button. Times are shown in your device’s time zone.
Blue hour windows
How it works
Blue hour is defined here as the window when the sun sits between -8° and -4° of elevation - the accepted “deep-blue” band. At -8° the last direct sunlight has faded and the sky is noticeably dark; at -4° the glow at the horizon builds toward the warmer pre-sunrise (or post-sunset) light that photographers call golden hour. In the morning blue hour ends where golden hour begins; in the evening the reverse happens.
Times are computed with the standard NOAA solar-position equations, so they shift naturally with your date, latitude and longitude. The displayed clock is whatever time zone your device is set to.
What blue hour is good for
- Cityscapes and architecture - windows light up against a blue sky still holding colour.
- Seascapes, lakes and rivers, where the cool even light makes long water silky without hard shadows.
- Long exposures with streetlights or headlight trails - the sky is dark enough for them to read clearly.
- A moodier, cooler alternative to golden hour for portraits and cars.
Example
For New Delhi (28.6°N, 77.2°E) on 15 June the calculator reports a morning blue hour from about 04:46 to 05:06 (sun -8° to -4°), with civil twilight beginning around 04:56 and sunrise at 05:22. In the evening blue hour runs from roughly 19:37 to 19:57, just after sunset at 19:20. Times are local Delhi time and good to about ±2 minutes.
Related sky planning
Want the warm side of the same window? Use the golden hour calculator. Need the full civil, nautical and astronomical twilight times? See the sunrise & sunset calculator. Shooting at night under a dark sky? Check the moon phase calculator first.
Frequently asked questions
What is blue hour?
Blue hour is the cool, soft period before sunrise and after sunset when the sun is just below the horizon. This calculator uses the common definition of a solar elevation between -8° and -4°: dark enough for deep-blue tones, bright enough that the sky still carries colour.
How is blue hour different from golden hour?
Golden hour happens when the sun is low above the horizon (about -4° to +6°) and the light is warm. Blue hour happens earlier in the morning and later in the evening (about -8° to -4°), when the sky is a deep, even blue with cool shadows and no direct sunlight.
How long is blue hour?
Usually about 20–40 minutes, split into a short morning window and an evening window of similar length. Duration depends on latitude and season - near the equator it is brief, while at high latitudes in summer it can stretch for a long time or disappear entirely around midnight sun.
Are the times exact?
They are accurate to roughly ±2 minutes, which is plenty for planning a shoot. Actual terrain, clouds, haze and air pollution all shift what you actually see, so treat the windows as a guide and arrive with a margin.