How to Calculate Your Exact Age

Exact age requires subtracting birth date from the reference date, borrowing from months and years when necessary — like manual date arithmetic.

Step-by-step

1. Write the as-of date and birth date in YYYY-MM-DD format.
2. Subtract birth year from as-of year.
3. If birth month/day hasn't occurred yet this year, subtract 1 from years.
4. Subtract birth month from as-of month; borrow 12 if negative.
5. Subtract birth day from as-of day; borrow days from previous month if negative.
6. Use our Age Calculator to handle leap years and month lengths automatically.

Tips and common mistakes

• Leap year birthdays (Feb 29) — some systems use Feb 28 or Mar 1 in non-leap years
• Legal age may depend on jurisdiction and whether birthday has passed

Open the Age Calculator to apply these steps with your own numbers instantly.

Frequently asked questions