How to Calculate Your Exact Age in Years, Months and Days
How day-borrowing works, and how leap-year birthdays are handled.
3 min read
Step by step
- Subtract the birth year, month and day from the target date's parts.
- If days are negative, borrow the length of the previous month and drop one month.
- If months are then negative, add 12 and drop one year.
- February 29 birthdays are observed on February 28 in non-leap years.
Key takeaway: Calendar age needs borrowing, not simple division of total days.
Do it automatically
Exact age in years, months, days — plus your next birthday.
Open the Age Calculator