Age Calculator

Enter a date of birth to get your exact age in years, months and days, plus totals and a next-birthday countdown. Free, fast, private.

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Total days
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Total weeks
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Total months
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Total hours

How to use the Age Calculator

  1. Enter a date of birth in the first field.
  2. Optionally set a different "as of" date if you want the age calculated at a specific point in time rather than today.
  3. Click "Calculate age" to see the exact breakdown in years, months and days.
  4. Scroll down for total days, weeks, months and hours lived, plus a live countdown to the next birthday.

Why use ZillaKit's Age Calculator?

Figuring out someone's exact age down to the day is more fiddly than it looks, since months have different lengths and leap years shift the math. ZillaKit's age calculator handles all of that correctly, taking a date of birth and computing the precise number of full years, months and remaining days elapsed, using calendar-aware date arithmetic rather than a naive day-count divide. It also totals up the same lifespan in whole days, weeks, months and hours, which is handy for legal forms, medical records, trivia, or just satisfying curiosity about a big number. An optional "as of" date lets you calculate age at any past or future point rather than only today, useful for eligibility checks, historical questions, or planning ahead. A live countdown shows exactly how long until the next birthday. Everything runs instantly in your browser using plain JavaScript date logic, with no upload, no signup, and no limit on how many times you use it.

FAQ

How is the years/months/days breakdown calculated?

The calculator counts whole calendar years and months elapsed between the two dates, then reports the leftover days, correctly handling different month lengths and leap years rather than just dividing total days.

Can I calculate age as of a date other than today?

Yes, use the optional "Calculate age as of" field to set any date, past or future, and the results will be based on that date instead of today.

Why do the total days and total weeks numbers look so large?

Those are true lifetime totals — every single day and week that has passed since birth — rather than a broken-down calendar age, so they naturally add up to much bigger numbers than "years old."

Does it account for leap years?

Yes, all calculations use native date arithmetic that correctly accounts for leap years and varying month lengths automatically.

Is my date of birth stored or uploaded anywhere?

No. All calculations happen locally in your browser using JavaScript's Date object. Nothing is sent to a server or saved.