Golden Hour Calculator

In short Golden hour is defined by the sun altitude, not by the clock, and it is almost never an hour. It runs from the horizon up to about 6 degrees, and how long the sun takes to cross that band depends entirely on how steeply it climbs — which depends on your latitude and the date. At the equator on an equinox it is about 25 minutes. In London on the June solstice it is roughly 50 minutes. At high latitude in midsummer the sun crawls along near the horizon instead of climbing away from it, and the window can run for hours. The light changes because of how much atmosphere it is travelling through. With the sun low, sunlight takes a long slanting path through the air, which scatters the blue end out and leaves the warm reds and oranges — the same reason a sunset is red rather than white. It also arrives almost horizontally, so subjects are lit and shadowed along their length rather than from above, which is what gives the long shadows and the modelled faces. Blue hour is the other side of the same effect: from about 6 to 4 degrees BELOW the horizon, when the sun itself is gone but the upper atmosphere is still lit, the sky glows a deep even blue that balances well against artificial light. That is the window for cityscapes and lit interiors shot from outside. One practical warning: all of this assumes a flat sea-level horizon, and every degree of hills, trees or buildings takes several minutes off the end of your evening window.