Length of Daylight Calculator

Latitude

Date

Result

Daylight17 h 34 min
Night6 h 26 min
Gain or loss+0 min a day
Longest day of the year17 h 34 min
Shortest day of the year7 h 0 min
Share of daylight, %73.2

The day does not lengthen evenly

Calculates the length of daylight for a latitude and date, how fast it is changing and the longest and shortest days of that year.

Around the solstices the length of the day barely moves — a few seconds a day, which is where the word solstice comes from. Around the equinoxes it changes fastest, by four or five minutes a day in mid latitudes.

How dramatic all this is depends entirely on latitude. At the equator the day sits near twelve hours all year; at sixty degrees it swings between six and nineteen.

What this calculator shows

The length of the day and of the night
The change from today to tomorrow
The longest and shortest days of the year at that latitude

What to keep in mind

Daylight is measured between sunrise and sunset at a zenith of 90.833°, refraction included.
The solstices are taken as 21 June and 21 December, which is within a day of the real dates and within seconds of the real length.

FAQs

How much does the day lengthen in spring?

Around four to five minutes a day near the equinox in mid latitudes, slowing to seconds as the solstice approaches.

Why is the day twelve hours at the equinox rather than exactly?

Because sunrise counts the upper edge of the disc and refraction lifts the image. Equal day and night actually falls a few days before the spring equinox.

Why does the earliest sunset not fall on the shortest day?

Because solar noon itself drifts through the year by up to a quarter of an hour. The earliest sunset comes about two weeks before the winter solstice and the latest sunrise about two weeks after it.

What happens beyond the polar circle?

The day reaches twenty-four hours or zero. The tool reports those as a full day or a full night rather than a time.

Worked example

Moscow on the longest day

Input: 55.75° N, 21 June 2026

Output: 17 hours 34 minutes

Note: That is 73 percent of the twenty-four hours. The shortest day at the same latitude is 7 hours exactly, so the swing across the year is more than ten hours.

Useful links

All tools in Nature and weather calculators

Length of Daylight Calculator

Result

Related tools

Sunrise and Sunset Calculator

Moon Phase Calculator

Day of the Week Calculator

Useful links