Age on the date that matters
Enter a birth date and choose the date to compare it with. The result gives calendar years, months, and days, followed by total days lived. It also finds the next birthday and the next multiple of 1,000 days.
Someone born October 3, 2000 is 26 years, 0 months, and 0 days old on October 3, 2026. On October 2, 2026, the result is 25 years, 11 months, and 29 days. A birth date equal to the comparison date gives zero.
Calendar months, not average months
The calculation finds the largest whole-month move from the original birth date that does not pass the comparison date. Each move goes directly from that original date, using the target month’s last day if needed. Remaining calendar days are counted after that anchor. The Temporal calendar-date documentation explains why calendar dates are separate from time zones and elapsed time.
Gregorian dates from years 0001 through 9999 are supported. A birth date after the comparison date needs correction. A future birthday or milestone beyond year 9999 is omitted or marked outside the range. Birth times, local legal birthday rules, and historical calendar changes are not included.
To add a specific number of days or years instead, use the Date calculator.