Age Calculator
Exact age in years, months and days
Give it a date of birth and it does the calendar arithmetic that trip people up — the part where a birthday on the 31st, or a February birthday in a leap year, or an age where the month has to borrow days from the previous month. The result is a plain breakdown like 24 years, 7 months and 3 days, computed by counting whole years, then borrowing the leftover days from the last day of the previous month before decrementing the month count, which is how a human reads an age. Alongside it you get total days lived, the same figure in hours, and a live count of days to the next birthday — zero on the day itself, plus the weekday you were born on. The clock it reads is your device's.
Work out an exact age from a date of birth — in years, months, days and total days lived — plus the next birthday countdown. Handy for forms, trivia and milestone planning.
Private Age Calculator In Your Browser
Age Calculator is processed locally with client-side JavaScript. Your files never touch a server, and there is no queue to wait in.
How to use Age Calculator
Open the Date of birth field and pick a day from the calendar picker.
Read the age breakdown, which counts whole years, then months, then days from your birth date to today.
Check the total days lived and total hours figures, both measured from midnight on your birth date.
Look at the next-birthday line: it counts down to zero on the day and names the weekday you were born on.
- Month lengths are handled properly — when the day count goes negative it borrows from the last day of the previous month, so a 31 January birth date is not off by one.
- A birth date in the future returns an explicit error instead of producing a negative age.
- The countdown handles birthdays that have already passed this year by rolling the target forward twelve months.
- All arithmetic runs from your device clock, so the answer reflects your local midnight-to-midnight days rather than UTC.
- A parent filling in a school enrolment form needs the exact age in years, months and days rather than a rounded figure.
- A project manager checking whether a candidate meets a minimum-age requirement reads the days-lived count alongside it.
- Someone planning a milestone birthday works out how many days remain before turning the next round number.