Date difference & age
Count calendar days or completed years between dates.
How this works
Subtract calendar dates using UTC to avoid daylight-saving errors. Completed years compare the month and day.
Example
Using the example inputs, calendar days is 13,309.
- Start / birth date
- 1990-05-15
- End / as-of date
- 2026-10-22
- Calendar days
- 13,309
Elapsed days exclude the starting date. A February 29 anniversary is treated as March 1 in non-leap years.
Scope and assumptions
Not a legal-age or deadline calculator; leap-day anniversary rules may differ by jurisdiction.
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