EpochLab

Day Length Calculator

How long is the day?

Hours of daylight for any place and date, how much it changed since yesterday, and the longest and shortest days of that year at that latitude.

Questions people ask

The things that come up about day length calculators, answered plainly.

How fast does the day get longer?

It depends on latitude and time of year. At 50° north the day gains about four minutes around the equinoxes and almost nothing near the solstices — the change follows a sine curve, which is why late February feels like it is getting light so quickly.

Is the day exactly 12 hours at the equinox?

No — it is about 12 hours and 7 minutes, because sunrise and sunset are defined by the disc's edge rather than its centre, and refraction lifts the image. The date with exactly 12 hours, the equilux, falls a few days either side of the equinox depending on latitude.

Related tools

Sunrise, sunset, the golden hour and the phase of the moon, anywhere on Earth.

Night Length CalculatorDarkness for any place and date — from sunset to sunrise, and separately the true astronomical night, which at high latitudes disappears entirely in summer.
Sunrise CalculatorSunrise for any place and date, with the twilights before it, the bearing the sun comes up on, and how much earlier or later it is than yesterday.
Sunset CalculatorSunset for any place and date, the twilight that follows, the bearing it goes down on, and how long you have before it is properly dark.
Solar Noon CalculatorTrue solar noon for your location — usually nowhere near 12:00 on the clock — with the sun's altitude at that moment and the shadow length it casts.

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