Date difference calculator
A calendar difference borrows from real month lengths rather than dividing by an average. From 1 January 2000 to 23 August 2026 is 26 years, 7 months and 22 days, not 26.64 years, which would be a different and less useful statement.
How to find a date difference
The awkward case is a month-end date. From 31 January to 1 March is one month and one day, because 31 January plus one month lands on 28 February and there is a day left over. Some tools answer two days, some answer −2, and some quietly give up. Anchoring the calculation on adding whole months, which clamps a short month properly; is the only approach that gets every pair right.
Questions
By adding whole calendar months to the earlier date until adding one more would overshoot, then counting the remaining days.
Because that gives a decimal, not a calendar answer. Nobody describes an age as 26.64 years.
One month and one day. 31 January plus a month is 28 February, leaving one day.
No: real month lengths are used, which is exactly why the breakdown differs from a simple division.
Yes, including 29 February as a start or end date.