Calculators
Age calculator
Calendar-correct, not just a subtraction: months are borrowed when the day of month is smaller, and the length of the previous month is used rather than an average of 30.
How to use it
- Pick your date of birth.
- Read your age as years, months and days.
- The table adds total days, weeks and hours lived.
- The line below shows the wait until your next birthday.
Legal age is not the same as elapsed time
In most jurisdictions you reach an age on the day before your birthday anniversary, though the exact rule varies: a person born on 15 June 2000 may legally turn 18 on 14 June or on 15 June depending on where they are. For anything with legal consequences — contracts, consent, pensions — the applicable rule matters more than the arithmetic.
Leap days and the missing anniversary
Someone born on 29 February has an actual birthday only once every four years. Most legal systems treat 1 March as the effective date in non-leap years; Japan and a few others use 28 February. This is also why dividing days lived by 365.25 gives a figure that slowly drifts away from the calendar-correct age.
Exact age for forms, cutoffs and eligibility
School entry, visa rules and pension eligibility are almost always defined by age on a specific date, not by elapsed days, so the answer you need is "years and months as of 1 September", which is exactly what a birthday-based calculation gives and a day count does not.
The leap-day case is worth checking deliberately. Someone born on 29 February has, in most legal systems, a birthday of 28 February or 1 March in non-leap years — and which one is chosen can put them on the wrong side of a cutoff by a day.
Frequently asked questions
Why not just subtract the years?
Because that gives a number that is wrong for most of the year. Someone born in December 1990 is 34 in June 2025 by subtraction, but has not had their birthday yet and is still 34 years and 6 months old — the month-and-day borrowing is what makes the figure exact.
How are leap years handled?
The calculation uses real calendar months, so 29 February is taken into account automatically. Someone born on that date sees their birthday fall on 1 March in non-leap years, which is the common legal convention in most jurisdictions.
Is the day count inclusive?
It counts elapsed days from birth to today, so a baby born today shows zero. Time zones are ignored — the calculation uses local midnight.
Can it calculate age at a past date?
Not directly. For a historical age, subtract the two dates with the date-difference tool instead.
How is age counted for visa and passport forms?
In completed years on the date of application, not rounded up. One day short is a rejection, so check the exact date rather than the year difference.
Why does the day count look off by one?
Because a date range can be counted inclusively or exclusively. 1 to 3 January is two days elapsed, three days inclusive.