Blue Hour Calculator

What is blue hour?

Blue hour is the short window of twilight when the sun is between about 4° and 6° below the horizon — right after golden hour ends in the evening, or just before it begins in the morning. The sky glows a deep, even cobalt while there is still enough light to expose a scene, which is why it pairs so well with the warm artificial lights of a city.

Despite the name it rarely lasts a full hour: 20–40 minutes at mid-latitudes, shorter near the equator, longer toward the poles. The calculator above gives tonight's exact window for your location.

How to shoot blue hour

Use a tripod — exposures run from a fraction of a second to several seconds — keep ISO low for clean files, and shoot RAW so you can fine-tune the intense blue afterward. City skylines, bridges, water reflections and lit interiors all shine now. Set up for golden hour first and simply stay put; blue hour follows for free.

Want the full breakdown? Read Blue hour explained: when it happens and how to shoot it.