Age is broken down into whole years first, then leftover months, then leftover days — a calendar-aware calculation rather than a simple day count divided by 365.25, which handles month-end edge cases correctly (like 31 January plus one month correctly landing on 28 or 29 February depending on the year).
Date difference uses that same calendar-walking method, stepping through actual months and years rather than assuming every month is the same length — this matters most for date ranges spanning February or months with different day counts.
The total-days figure between two dates is calculated differently — simply the millisecond gap between the two dates rounded to whole midnights — which is the more useful number when you just want a raw day count rather than a broken-down years/months/days figure.
They're calculated differently on purpose: the breakdown walks the calendar month by month (accounting for different month lengths), while the total days figure is a straight count of 24-hour periods between the two dates. Both are correct, just answering slightly different questions.
It clamps to the actual end of the target month — so 31 January plus one month correctly lands on 28 or 29 February (depending on leap year) rather than an invalid '31 February'.
Yes — the calendar-walking method used for both age and date-difference calculations naturally respects each year's actual length, including leap years.
Yes — enter any two dates (a birth date and any target date) and the calculator works out the age or difference between them, not just age as of today.
