What does this calculator do?
It counts how many days are between two dates — and it gets leap years and different month lengths right automatically, so you do not have to count on a calendar.
// physics › Clock & Calendar
Days Between Dates
Count the calendar-accurate number of days between two dates, with an inclusive or exclusive option.
days = end − start
Frequently asked questions
What is the difference between inclusive and exclusive?
Exclusive counts only the gap: from 1 March to 3 March is 2 days. Inclusive counts both end days as well, giving 3 days. Use inclusive when you are counting the length of an event (like 'how many days is my holiday').
Can you show an example?
From 1 January 2026 to 31 December 2026, exclusive, is 364 days. The year 2024 is a leap year, so the same span there is 365 days — the calculator counts the extra 29 February for you.
How do I type the dates?
Use the format YYYY-MM-DD — for example 2026-03-01 for the 1st of March 2026. Year first, then month, then day.
Does the order of the dates matter?
No — if you put the later date first, the calculator still gives the size of the gap. It reports the number of days either way.
Where would I use this?
Counting days until a deadline or holiday, working out someone's age in days, or measuring how long a project ran.