Date & Time
Age Calculator
Calculate exact age in years, months, and days.
What is this tool?
Enter a date of birth and the age calculator returns the exact age in years, months, and days, along with the total number of days lived. Set a different as-of date to find out how old someone was, or will be, on a specific day.
Age is calculated using calendar dates in UTC to avoid timezone edge cases around midnight. Results are informative, not legal determinations of age for eligibility.
How to use the Age Calculator
- Enter a birth date in YYYY-MM-DD format.
- Optionally set an as-of date (defaults to today).
- Read years, months, days, and total days lived.
Frequently asked questions
Which timezone is used?
Dates are interpreted as calendar dates (YYYY-MM-DD) without applying a local time-of-day, which keeps day boundaries consistent.
Can I calculate age on a future date?
Yes. Set the as-of date to any day after the birth date to see how old someone will be then.
Can I use the result for legal purposes?
It is accurate for everyday use, but it is not an official determination of age for eligibility, contracts, or legal documents.
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