Age Calculator
Pick a date of birth (or any past date) and get the exact elapsed time: full years, remaining months and days, the total number of days — and how long until the next birthday rolls around.
Why "just subtract the years" is wrong
Age arithmetic has three classic traps. Months have different lengths, so "3 months after January 31st" doesn't exist in February. Leap years make February 29th birthdays legal only one year in four — most jurisdictions still grant them legal age on February 28th or March 1st in non-leap years. And timezone offsets can shift a birth date by a full day when a naive script converts between UTC and local time. This page avoids the trap family by doing calendar arithmetic on local dates: borrow a month when the day-of-month hasn't arrived yet, borrow a year when the month hasn't.
FAQ
- Which birthday counts — the legal or the exact one?
- The calculator shows exact elapsed time. Legal age conventions for Feb 29 births vary by country; check yours for official purposes.
- What is the "as of" field for?
- It computes age at another moment — useful for historical records, forms asking "age at date", or planning ahead.
- Do you keep my birthday?
- Impossible — the field never leaves the page. No server sees it.