How to Calculate Your Age (Exactly)
"How old am I?" sounds trivial, but exact ages need three adjustments: whether your birthday has passed this year, how many full months have elapsed, and the number of days since the last month boundary — with leap years and uneven month lengths in the mix.
On this page
The Three-Part Age
An exact age is three numbers: completed years, completed months beyond those years, and days beyond those months. "26 years, 4 months, 30 days" is a complete statement of age; "26 years" alone hides 5 months of detail.
Step-by-Step Method
Example: born 15 March 2000, today 14 August 2026. Years: 2026 − 2000 = 26, and 15 March has passed, so 26. Months: March 15 → July 15 is 4 full months. Days: July 15 → August 14 is 30 days. Age: 26 years, 4 months, 30 days.
Leap Years and Month Lengths
Leap years add a 29th of February every four years (with century years only divisible by 400). When the reference date is 28 February and the birthday is 29 February, the standard convention treats the birthday as 28 February in non-leap years.
Month lengths also matter: "one month" from 31 January is 28 February in a non-leap year, not 3 March. Date arithmetic that simply adds 30 days gets this wrong — which is why a calculator beats mental maths.
Total Days and the Next Birthday
Beyond the three-part age, two numbers are useful: total days lived (every day between birth and the reference date, including leap days) and the days until your next birthday. The age calculator shows all of these at once.
Article FAQ
How is age calculated?
Subtract birth year from the current year, reduce by one if the birthday has not yet passed, then count the completed months and days since the last birthday.
What if I was born on 29 February?
In non-leap years the birthday is treated as 28 February, the convention used by most official systems.
Do leap years affect my age in days?
Yes — the total-days count includes every 29 February between birth and the reference date.