Age Calculator

Calendar-accurate: full years, then full remaining months, then leftover days, exactly the way a passport or hospital form computes age.

Yes — the calculation walks calendar months, so February 29 birthdays and leap day arithmetic come out correctly.

Yes — change the 'as of' date to any date after the birth date.

Birth times are rarely entered consistently, so the tool works on whole days and treats both dates in your local timezone.

Because months are not equal in length. The calculation takes whole years first, then whole months, then the remaining days - and when the day-of-month has not yet been reached, it borrows from the previous month, whose length varies between 28 and 31 days. The same number of elapsed days can therefore read as a different number of months and days depending on which months it spans.

In years that have no 29 February, the birthday is treated as falling on 28 February, both for counting a completed year and for the next-birthday countdown, so the two never disagree. Some jurisdictions use 1 March instead, so a legal age cut-off may land one day later. The total days lived is unaffected either way, since that figure counts actual elapsed days rather than calendar anniversaries.

Your device's local calendar date, with no time-of-day component. Dates are compared as dates, so the result does not shift when you cross a time zone, and there is no ambiguity around midnight. If you need an age at a precise instant rather than a calendar day, this is not the right measure.