An age calculator answers “how old is this person on this date” in years, months, and days. That is calendar arithmetic, not “days ÷ 365.” A child born 15 March 2020 is 4 years, 0 months, 0 days on 15 March 2024, even though 2020 was a leap year and the raw day count is not 4 × 365. Approximations are fine for back-of-the-envelope work. They are the wrong main result on an age page.
Enter a date of birth and a comparison date. The comparison date defaults to today. The result lists years, months, days, and a short phrase. If the comparison date is before the birth date, the status says so. This age calculator does not estimate life expectancy, BMI, or school grade. It is not a legal age for driving, drinking, or contracts.
Leap-day convention: a birth date of 29 February is treated as 28 February in a year that has no 29 February. So 29 February 2000 to 28 February 2001 is one year on this page. Other sites use 1 March. There is no universal civil rule; the convention is written next to the form.
Date fields use the browser date control. Invalid calendar dates (31 April) are rejected. The result is not a total-days counter; for that span between two arbitrary dates, use the Date Difference Calculator.
Let the comparison date be Y2-M2-D2 and the (possibly leap-clamped) birth date be Y1-M1-D1. Subtract years, months, and days. If days go negative, borrow one month and add that previous month’s length. If months go negative, borrow one year and add 12 months. That is the usual civil breakdown. It is not “elapsed seconds ÷ 31536000.”
Born 1 January 2000, age on 1 January 2010: 10 years, 0 months, 0 days. Born 31 January 2000, age on 1 March 2000: 0 years, 1 month, 1 day after the borrow from February. Born 29 February 2000, age on 28 February 2001: 1 year, 0 months, 0 days under the documented leap-day rule.
2000-01-01 → 2010-01-01 = 10y 0m 0d
2000-02-29 → 2001-02-28 = 1y 0m 0d (convention)People sometimes want “age in total days” or “age in decimal years.” Those are different readouts. Total days is a date difference from the birth date to the comparison date (exclusive or inclusive, depending on whether you count the birthday itself). Decimal years (days ÷ 365.25) reintroduce the approximation this page refuses as the main result. If you need total days, use the date-difference page with the same two dates.
If you need how many nights sit between two project dates, or inclusive versus exclusive day counts, that is the Date Difference Calculator, not this page. The two tools share calendar borrow math and keep different labels so you do not call a project span an age.
Uses calendar months and days, not 365-day years. A 29 February birthday in a common year is treated as 28 February. This is not a legal or medical determination.
No. Jurisdictions define age differently. This is a calendar count for everyday use, not a court or medical determination.
In a common year the anniversary is treated as 28 February. That is stated on the page.
Yes, when the field is empty on load. You can change it.
Age is oriented from a birth date and reports years/months/days of age. Date Difference reports exclusive and inclusive day counts between any two dates.
