Age Calculator

The age calculation method

The Years / Months / Days result uses calendar-date subtraction with borrowing, exactly the way you would work it out by hand - not a rough "365.25 days" division. It takes the difference in years, months and days between your date of birth and the "as of" date, and if the day or month difference is negative it borrows from the previous month (using that month’s real length) or from the year.

Worked example: born 1 Jan 1990, measured as of 10 Mar 2026 gives 36 years, 2 months, 9 days - because 10 − 1 = 9 days and March (month 3) minus January (month 1) = 2 months, with no borrowing needed.

Total days lived is the whole number of 24-hour days between the two dates. Because it counts real calendar dates, leap years are automatically included. Age is measured in whole days from midnight-to-midnight, so it does not factor in your exact time of birth.

Zodiac sign & birthstone

The star sign uses the standard Western tropical date ranges (for example Aries 21 Mar–19 Apr, Taurus 20 Apr–20 May, and so on), and the birthstone follows the widely used traditional modern gem list. These are cultural and entertainment conventions, not scientific or medical facts - different traditions (sidereal/Vedic, or alternate gem lists) can give different answers, so treat these two fields as a fun extra.

Methodology & review

The age arithmetic follows the Gregorian calendar. Dates are read as calendar days (no time zone shifting of the result). Methodology last reviewed: October 2026. All calculation happens in your browser; your date of birth is never uploaded or stored.