Age Calculator
Calculate your exact age in years, months, and days
How to use
- Enter your birth date
- View your age in years, months, and days
- See total days, weeks, and months lived
Use cases
- Personal records
- Planning birthdays
- Historical calculations
- Document verification
About the Age Calculator
An age calculator turns a birth date into a precise age — years, months, days — plus aggregate totals (days, weeks, months lived). Seemingly trivial, but leap years, month boundaries, and timezone parsing make it surprisingly easy to get wrong. This tool uses strict UTC calendar math so results are consistent worldwide.
Features
- Exact years / months / days
- Total days, weeks, and months lived
- Optional target date (not just today)
- UTC calendar math — no timezone off-by-one
- Rejects invalid dates like Feb 30
How it works
- Enter your birth date.
- Optionally enter a target date (defaults to today).
- See exact age plus total days, weeks, months lived.
Frequently asked questions
How do you handle February 29 birthdays?
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Correctly — on non-leap years, the 'birthday' is treated as March 1 for 'today is my birthday' checks, matching legal convention in most jurisdictions.
Why UTC instead of local time?
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Dates-without-time are timezone-ambiguous. Parsing them in UTC prevents an off-by-one-day bug when users are several hours ahead or behind the date boundary.
Can I calculate age as of a past date?
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Yes — the optional 'Calculate Age On' field lets you use any target date, past or future.
Is my birth date stored?
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No. Everything runs locally in your browser.
Why do total days and year-month-day totals differ?
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Months have different lengths, so 1 year + 1 month is sometimes 365 days and sometimes 367. Total days is the raw calendar difference.