How to Calculate Your Exact Age
Last updated 2026-09-11
Calculating age sounds trivial — subtract the birth year from the current year — but that only works if the birthday has already happened this year.
Start with the year difference
Subtract the birth year from the current year.
Check whether the birthday has occurred yet
If today's month and day are before the birth month and day, subtract 1 from the year difference.
Work out the remaining months and days
Count the months and days between the last birthday and today for a precise years/months/days figure.
Example
Someone born on March 14, 1990 calculating their age on January 5, 2026 is 35 years old (not 36), because their 2026 birthday hasn't happened yet.
Important Considerations
- Leap years affect exact day counts but not the year/month/day breakdown, since it's based on calendar dates rather than a fixed day count.
- Some contexts (contracts, eligibility rules) calculate age as of a specific date rather than today — check what's required.
Frequently Asked Questions
- Why isn't age just "current year minus birth year"?
- Because that only holds true once the birthday has passed this year. Before the birthday, the true age is one year less.
- Does a leap year birthday (Feb 29) cause problems?
- Most systems treat Feb 29 birthdays as falling on Feb 28 (or Mar 1) in non-leap years for the purpose of counting age.