Date Difference Calculator
Count the days, weeks, months, and years between two calendar dates.
How to use this calculator
- Enter the start and end dates in either order.
- Choose whether to include the end date — 'count both endpoints' is what most people want for vacation or rental lengths.
How it works
The standard count measures midnight-to-midnight boundaries: from Monday to Tuesday is 1 day. Adding 1 gives the inclusive count used for 'how many nights and days does my trip span'.
The calendar span decomposes the interval into whole years, months, and leftover days — the same convention the age calculator uses.
Leap days are simply days; February 29 counts like any other date.
Worked example
From January 1, 2026 to March 1, 2026.
- 1January has 31 days, February 2026 has 28
- 231 + 28 = 59 (standard count)
- 3Inclusive count = 60
59 days between, or 60 days counting both dates.
When this calculator is useful
- Countdowns to events
- Rental and booking lengths
- Project durations
- Contract notice periods
Frequently asked questions
Is the end date counted?
By default no — that matches how most date arithmetic works. Switch the toggle to 'Yes' to include both endpoints.
Does the order of dates matter?
No. The calculator always reports the absolute difference.