Age Calculator
Enter a birth date and get the exact age in years, months and days, along with the total days lived, the weekday you were born on and the countdown to the next birthday. The 'as of' date defaults to today but accepts any date, so you can work out how old somebody was at a particular moment — or will be at a future one. Age here is calendar age, counted the way people actually count it: the years advance on the birthday, not after a fixed number of days. That distinction matters because months have different lengths, so the same span of days produces different month-and-day figures depending on where in the calendar it falls. Everything is computed in your browser from the dates you type; nothing is sent anywhere.
Age
26 yr 7 mo 20 d
- Total days
- 9,729
- Total weeks
- 1,389
- Total hours
- 233,496
- Born on a
- Saturday
Next birthday
2027-01-01(133 days to go)
How to use
- Pick your birth date.
- Leave 'as of' set to today, or change it for any other date.
- Read your age and total days lived.
- See the date and countdown to your next birthday.
Frequently asked questions
- How is age calculated?
- Calendar-accurate: full years, then full remaining months, then leftover days, exactly the way a passport or hospital form computes age.
- Does it handle leap years?
- Yes — the calculation walks calendar months, so February 29 birthdays and leap day arithmetic come out correctly.
- Can I see how old someone was on a past date?
- Yes — change the 'as of' date to any date after the birth date.
- Why no time-of-day?
- Birth times are rarely entered consistently, so the tool works on whole days and treats both dates in your local timezone.
- Why doesn't the months figure match subtracting the dates?
- 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.
- What happens with a 29 February birthday?
- In years that have no 29 February, the birthday is treated as falling on 1 March for the purposes of counting a completed year, which is the common civil convention. The total days lived is unaffected either way, since that figure counts actual elapsed days rather than calendar anniversaries.
- Which time zone is used?
- 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.
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