Age Calculator
Put in a date of birth and get the exact age, not a rounded one. Years, months and days, plus a few totals that are oddly satisfying to look at.
Why age arithmetic is fiddlier than it looks
Subtracting two years gives you a number that is wrong roughly half the time. Someone born in December 1995, measured in March 2026, is 30 by subtraction and 30 years and 3 months in reality, but someone born in December 1995 measured in October 2026 is 31 by subtraction and only 30 years and 10 months in fact. The birthday has not happened yet.
The correct method works down the units. Compare days first, borrowing from months if the day of the month has not been reached. Then compare months, borrowing from years if needed. Only then is the year count correct. That borrowing step is what this calculator does, and it is what most quick mental estimates skip.
Leap years
A year is a leap year if it divides by 4, except century years, which must divide by 400. So 2000 was a leap year and 1900 was not. This matters for the total days figure, which counts actual elapsed days rather than assuming 365 per year.
People born on 29 February have a birthday in only about one year in four. In most legal contexts in non leap years the birthday is treated as 1 March, though the specific rule varies by jurisdiction and by the purpose being served.
Age at a date other than today
The second field is more useful than it looks. Set it to a date in the past to answer how old someone was at an event. Set it to a date in the future to check eligibility.
That is the common practical use in India: confirming whether someone will be 18 on polling day, 21 for a particular licence, 60 for senior citizen benefits, or the specific age a scheme or examination requires on a stated cut off date. Cut off dates in Indian admissions are usually fixed, so being a week late can matter, and eyeballing it from a birth year is exactly how people get it wrong.
What the totals mean
Total days is calculated from the actual calendar, including every leap day. Total months counts completed months only, so it ignores the leftover days. Total weeks is total days divided by seven and rounded down. None of these are approximations from an average year length.
Common questions
Does this handle leap years correctly?
Yes. The total days figure is derived from actual calendar dates rather than multiplying by 365, so every leap day in the period is included.
What about someone born on 29 February?
The calculator computes the exact elapsed time either way. For the next birthday in a non leap year, most systems and most legal rules in practice treat 1 March as the effective date, though the precise convention varies by purpose.
Can I calculate age at a past date?
Yes. Change the second field from today to any date. This is the usual way to check what someone's age was on a scheme's cut off date or at the time of an event.
Why does my age in months not equal years times twelve?
Total months counts only completed months, so the leftover days are dropped. Someone who is 30 years and 5 months and 20 days has 365 completed months, not 365 and a bit.
Is my date of birth stored anywhere?
No. Everything runs inside your browser and nothing is transmitted. Close the tab and it is gone.