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Age Calculator
Calculate your exact age in years, months and days — plus total weeks, days, hours, minutes and seconds.
Runs entirely in your browser — nothing you type is uploaded.
How to use the Age Calculator
- Enter your date of birth.
- Leave “calculate as of” on today for your current age, or set it to any other date on or after your birth date.
- Press Calculate Age (or the Enter key). Your exact age appears instantly, with a full breakdown you can copy.
- Use Reset to clear the fields and start again.
What the Age Calculator does
The Age Calculator works out exactly how old you are — or how old you were, or will be, on any date — from your date of birth. As well as the familiar “years, months and days”, it shows your age expressed as total months, weeks, days, hours, minutes and seconds, which is handy for milestones and curiosity alike.
How the calculation works
Ages are calculated with calendar-aware arithmetic, not a rough “365 days a year” estimate. The tool first counts the number of whole months between the two dates — taking each month’s real length and leap years into account — and then adds the remaining whole days. The totals (weeks, days, hours, minutes and seconds) come from the exact number of days between the two dates. All of this uses date-only maths, so results are not affected by time zones or daylight-saving changes and are the same for everyone.
Leap years and month lengths are handled correctly, including 29 February birthdays: in a non-leap year that anniversary is treated as 28 February, so age still advances once per year in a predictable way.
Benefits and use cases
- Know your exact age for forms, applications and eligibility checks.
- Plan milestones — see how many days until a round-number birthday or anniversary by choosing a future “as of” date.
- Work out someone else’s age at a particular date, such as on a specific event.
- Fun facts — find out how many weeks, hours or seconds you have been alive.
Is it private?
Yes. The Age Calculator runs entirely in your web browser using JavaScript. The dates you enter are never sent to a server, never stored, and never shared — close the tab and nothing remains. There is no sign-up and no tracking.
Frequently Asked Questions
Is the Age Calculator free?
Yes. It is completely free to use, with no account, sign-up or limits.
How is my exact age calculated?
Your age is calculated using calendar-aware arithmetic: full years and months are counted first (respecting each month’s real length and leap years), and the remaining whole days are added. It is not a rough 365-days-per-year estimate.
Is my date of birth uploaded or stored?
No. Everything is calculated locally in your browser using JavaScript — the dates you enter are never sent to a server, saved or shared.
How does it handle leap years and 29 February birthdays?
Leap years and month lengths are handled correctly. For a 29 February birthday in a non-leap year, the anniversary is treated as 28 February, so the age still advances once per year in a deterministic way.
Can I calculate age as of a past or future date?
Yes. Leave the “calculate as of” date on today for your current age, or set it to any date on or after the date of birth to find the age at that point in time.