Calculate exact age in years, months, and days. Find total days lived and days until your next birthday.
Age calculation seems simple but has subtleties — months have different lengths, and leap years add an extra day every 4 years. The correct method counts full completed years first, then remaining months, then remaining days.
For example, if you were born on March 15, 1990 and today is May 8, 2026: you completed 36 full years (March 15, 1990 → March 15, 2026), then 1 full month (March 15 → April 15), then 23 days (April 15 → May 8) = 36 years, 1 month, 23 days.
In total days: simply subtract your birth date from today. A person born January 1, 1990 has lived approximately 13,277 days (as of 2026). Each leap year adds one extra day to the count.
Chronological age is the elapsed time between a birth date and a reference date, expressed in years, months and days. The calculation counts complete years first, then complete months, then remaining days — borrowing days from the previous month when needed, which is why results depend on the differing lengths of calendar months.
Someone born 15 March 2000 is, on 2 July 2026, exactly 26 years, 3 months and 17 days old — 9,606 days in total.
How do leap years affect age? A person born 29 February legally ages on 28 February or 1 March in non-leap years depending on jurisdiction; day-counting handles this automatically.
Why do East Asian age systems differ? Traditional Korean and Chinese reckoning counted a newborn as one year old and added a year at New Year, so traditional age can exceed Western age by up to two years.