Exact age in years, months, and days - leap years and uneven months handled the way a calendar actually works, not by dividing by 365.
Subtracting dates the naive way breaks on real calendars: months have 28 to 31 days, and February grows a day in leap years. This tool uses the standard date-subtraction method - full calendar years first, then full months by day-of-month, then leftover days, borrowing the true length of the previous month when needed. One honest edge case: someone born March 31 completes their first calendar month on May 1 under this rule, because April never reaches a 31st. Calculators genuinely differ on days like that - this one states its convention rather than hiding it, and the total-day count below the result is convention-free either way.
Born February 29? Under this tool's counting rule your year completes on March 1 in non-leap years - exactly 1y 0m 0d - which matches how most jurisdictions treat leap-day birthdays legally, and the next-birthday countdown uses the same March 1 convention. Your exact age in days is unaffected either way, since it's a plain day count.
Working with dates for a different reason? The time zone converter shows one moment across 17 world cities at once.