Find your exact age in years, months, days — plus total hours and days until your next birthday.
An age calculator determines the exact time elapsed between two dates — typically from a date of birth to the current date or a specified reference date. Unlike a simple subtraction of years, a proper age calculator accounts for the varying lengths of months (28, 29, 30, or 31 days), leap years (which add an extra day to February every four years), and the exact day within the current month to provide results in precise years, months, and days.
The algorithm works in three steps. First, it checks whether the birthday has occurred yet in the current year — if not, it subtracts one from the year count. Second, it calculates the remaining months by checking whether the current day of the month is past the birthday day — adjusting accordingly. Third, it calculates the remaining days, borrowing from the previous month if necessary. Total days lived and total hours are derived from the millisecond difference between the two timestamps.
The tool also calculates days until your next birthday — useful for planning celebrations, tracking milestones, or simply satisfying curiosity. If today is your birthday, it displays a birthday message instead of a day count.