How exact age is calculated
This calculator finds your exact age using calendar-based arithmetic — subtracting your birth date from today's date year by year, month by month, and day by day — rather than simply dividing total days lived by 365. This matters because months have different lengths and leap years add an extra day, so a naive day-count calculation can be off by several days.
Why your next birthday countdown matters
The countdown shows exactly how many days remain until your next birthday, accounting for whether it has already passed this year and rolling over to next year if so.