Blue Hour Calculator
When the sky turns deep blue — exact times for the week ahead.
Blue hours for
What is blue hour?
Blue hour is the stretch of civil twilight when the sun sits between about 4° and 6° below the horizon. Direct sunlight is gone, but the upper atmosphere still scatters short blue wavelengths across the sky — deep, even, saturated light that city lights and architecture love. It is brief: this calculator computes the true solar altitude for your coordinates so you know the exact window rather than a rule of thumb.
FAQ
- How is blue hour different from twilight?
- Blue hour is a slice of civil twilight. Twilight spans everything from sunset to full darkness; the blue-hour window is the narrow band where the sky reads as rich blue rather than pale dusk or black night.
- Why is the window so short?
- The sun only spends a few minutes crossing two degrees of altitude at mid latitudes. Closer to the poles it lingers — and around the solstices it can last an hour or more, or never end at all.
- What should I shoot during blue hour?
- Skylines and architecture (window light balances the sky), reflections on water, neon and street scenes — anywhere artificial light and ambient light reach the same level for a few minutes.