calc / date & time / AGE

Age Calculator

Exact age the way official forms want it — years, months, days — plus the totals nobody computes by hand and the weekday of your next birthday.

From date of birth to any “as on” date

Age

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Total days lived

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Next birthday

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§1How age is counted

Age in years/months/days is a borrow subtraction on the calendar, not a division of elapsed days:

years = whole birthdays passed months = whole month-anniversaries since the last birthday days = days since the last month-anniversary (borrowing from the previous month's actual length when needed)

That borrowing step is why two people can be “30 years, 1 month, 29 days” and “30 years, 2 months, 0 days” with birthdays only two days apart — month lengths differ.

Worked example — born 15 June 1990, as on 31 July 2026

years: 1990 → 2026, birthday already passed → 36 months: 15 Jun → 15 Jul passed, 15 Aug not yet → 1 days: 15 Jul → 31 Jul → 16 age = 36 years, 1 month, 16 days (13,195 total days)

Note the days step counts from the last month-anniversary (15 July), and if the current day-of-month were smaller than 15 it would borrow the previous month's real length — 30, 31, 28 or 29 — which is why ages shift unevenly around month ends.

§2The gotchas

Leap-day birthdays

Born on 29 February? In non-leap years the birthday is counted on 1 March here (the first moment you've completed the year), which is also what most legal systems do — India's included.

“Completed years” vs “running year”

Official forms want completed years — what this page shows. The colloquial “I'm in my 25th year” runs one ahead. Insurance uses yet another: “age nearest birthday”. Read the form.

§3Related

Day counter for days between any two dates, day of the week for the weekday you were born.