Age Calculator
Your exact age in years, months and days — computed on the calendar, not by dividing milliseconds, so the 31sts and February behave. With it: total days and weeks lived, the weekday you were born, and the countdown to the next birthday, leap-day birthdays handled honestly.
Calendar arithmetic is not division
An age is not elapsed time divided by 365.25 — it is a walk along the calendar: whole years first, then whole months anchored to the birth day-of-month, clamped where a short month cuts it off, then leftover days counted exactly. Every borrow this page makes is one a registry office would make on paper.
The same walk backwards gives the next birthday, which is why the countdown is exact through leap years — the two calculations share one calendar, not two approximations.
Frequently asked questions
Why do age calculators disagree by a day sometimes?
Because 'a month' is ambiguous when the days run out. From January 31, one month later lands on a February 28 that has no 31st — this page clamps to the month's end, the convention official forms use, so January 31 to March 1 reads one month one day. Millisecond-dividing tools invent other answers.
How is a February 29 birthday counted?
In common years the birthday falls on March 1 — the day after February ends, which is what most jurisdictions codify. The countdown here does exactly that, and in leap years the 29th is back. A leap-day child is not ageless three years out of four, whatever the jokes say.
What is the 'as of' date for?
Any question that is an age at some other moment: how old on graduation day, on a contract's date, at retirement. Age is a function of two dates, and fixing the second one turns the calculator into a document-checking tool rather than a birthday toy.
Why do total days matter when I have years and months?
Because years and months are unequal containers, and some questions need the honest unit: the ten-thousandth day falls around age 27, insurance and medicine sometimes count in days, and 'weeks lived' is the number that makes a life feel countable — about 4000 for a long one.
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