Calculate age on a chosen date, calendar years/months/days, total days and the next birthday.
Enter values, then calculate.
How the calculation works
Enter birth and reference dates. The default reference is today according to your device. We count complete calendar months, clamping an anniversary to the last day of a shorter month, then remaining days. February 29 becomes February 28 in a non-leap year. Hours and minutes are the total date span multiplied by 24 and 1,440.
Example and verification
2000-02-29 to 2023-02-28 gives 23 years, 0 months, 0 days and 8,400 total days. On the birthday, the countdown is zero.
Software checks cover the example, invalid input, zero or boundary cases, and reset in Chromium. No physical measurements or all-browser certification are claimed.
Scope and limitations
Gregorian dates only. This does not establish legal eligibility; an authority may use a different leap-day rule. Without a birth time, totals in hours/minutes are date-unit equivalents, not an exact lifetime clock.
Common questions
Why can another calculator differ?
Month-end and leap-day anniversary rules vary. Compare the rules, not only the final number.
Technical references
Related calculators
The calculator code processes your entries in this browser; it does not transmit or store them. Site analytics and advertising are governed separately by the site privacy policy.
Maintained by GadgetsFocus. Updated 2 October 2026 with AI-assisted writing and translation review; no human native-speaker or clinical review is claimed.