How to use the day night length change calculator
Copy today's and yesterday's sunrise and sunset from your local table and the page returns today's daylight length, the night length, the share of the day that is daylight, the day-over-day change in daylight and how far the sunrise and sunset have each moved. When you want to feel how fast the days are stretching, or to shift outdoor work and training to match the sunset, the per-day change in minutes is the number to watch.
How the numbers are produced
Daylight length is sunset minus sunrise, and night length is 1,440 minutes in a day minus the daylight length. The change is the difference in minutes between today and yesterday, and a difference of zero prints as no change so that a negative zero never appears. As of October 2026 the page uses clock arithmetic only.
Limits and what is not covered
Estimating sunrise and sunset from a latitude and a date is not covered. The page also ignores twilight brightness by phase, atmospheric refraction corrections and any correction for site elevation. Midnight-sun and polar-night tables, where sunset is not later than sunrise, stop the calculation and show a message instead.
Frequently asked questions
It is 1,440 minutes in a day minus the daylight length for today. The page splits one 24-hour day into two parts rather than counting from sunset to the next sunrise, so you never have to enter a time that belongs to the following date.
Sunrise and sunset depend on the latitude, longitude and elevation of the site, so a single estimate does not fit. This page takes the real times from the table you are reading and only measures lengths and changes from them.
They show how many minutes the daylight is gaining or losing per day and how far the sunrise and sunset have each moved. The change is smallest around the solstices and largest around the equinoxes.