Free online age calculator. Enter your date of birth to calculate the exact age in years, months, and days. Also find out the total days lived, weeks, next birthday countdown, day of birth, and zodiac sign.
The exact age is:
Age in years:
Age in months:
Age in weeks:
Age in days:
Day of birth:
Next birthday:
Zodiac sign:
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This calculator's main result —years, months, and days— is not obtained by dividing the total number of days by 365. It subtracts the civil calendar: first it counts the full years up to the last birthday, then the full months from that date to the same day of the as-of month and, finally, the days that remain. The year count only increases on the birthday, not on January 1.
An example: if the date of birth is May 7, 2000 and the as-of date is August 17, 2026, from May 7, 2000 to May 7, 2026 26 years have already been completed. From that birthday to August 7 there are 3 full months. Finally, from August 7 to August 17, 10 days remain. The exact age is therefore 26 years, 3 months, and 10 days.
Chronological age is the time elapsed from the date of birth to today, or to another as-of date. It is expressed in calendar years, months, and days: the usual way to say how old a person is. This calculator returns that age, not an estimate of physical condition or biological aging.
In Excel you can get the same breakdown as this calculator by putting years, months, and days in separate cells. Put the date of birth in A2 and the as-of date in B2. If you are measuring as of today, replace B2 with TODAY().
Completed years run from birth to the last birthday before the as-of date. In Excel they are calculated by the DATEDIF function with the unit "Y": =DATEDIF(A2, B2, "Y"). The number only increases on the birthday, just as on this page.
Remaining months are those after that birthday and before the as-of date: a value between 0 and 11. DATEDIF returns them with the unit "YM", which ignores the years and leaves only those months: =DATEDIF(A2, B2, "YM"). In the May 7 to August 17 example, this result is 3.
Remaining days run from the same day of the month as the birthday to the as-of date. If that day has not yet arrived, Excel has to borrow the days of the previous month — the same rule as this calculator. One way to write it is: =IF(DAY(B2)>=DAY(A2), DAY(B2)-DAY(A2), DAY(DATE(YEAR(B2), MONTH(B2), 0))+DAY(B2)-DAY(A2)).
DATEDIF also accepts the unit "MD" for this same figure, but Microsoft documents that it can return an incorrect result. That is why we do not use it here.
Chronological age is the same for everyone with the same date of birth: it counts calendar time. Biological age tries to describe wear on the body and can vary with genetics and habits, so two people with the same chronological age need not “look” equally old. This tool does not calculate biological age; it only measures the time between the two dates.