How age is calculated
We compute the difference between your date of birth and today in full years, months, and days — the standard method used in most countries (you turn N on the Nth anniversary of your birth).
Both dates are read in your local timezone, so the result matches what you'd compute by hand on a calendar.
Calculating age by hand
Example: someone born on March 15, 1990, checking their age on November 8, 2026.
- Whole years: the most recent birthday was March 15, 2026, so they are 36.
- Whole months: count monthly anniversaries since then. October 15 is the 7th, and November 15 has not arrived yet, so 7 months.
- Remaining days: from October 15 to November 8 is 16 days left in October plus 8 days in November, so 24 days.
- Result: 36 years, 7 months and 24 days.
March 15, 1990 was a Thursday, and the next birthday, March 15, 2027, is 127 days away.
The same age in other units
| Unit | Total |
|---|---|
| Months | 439 |
| Weeks | 1,912 |
| Days | 13,387 |
| Hours | 321,288 |
Total days are counted on the real calendar, including every February 29 in between. Weeks are whole weeks, and hours are whole days × 24.
Edge cases
- Leap years — if you were born on Feb 29, most jurisdictions treat your birthday as Feb 28 or Mar 1 in non-leap years. This calculator counts it as February 28 in those years.
- Month ends — if you were born on the 31st, a month that has no 31st counts its last day as your monthly anniversary. Someone born January 31 is exactly 1 month old on February 29 in a leap year, or February 28 otherwise.
- Future dates — if you enter a date in the future, we'll show a message instead of a result.
Where exact age matters
Forms for school enrollment, sports age groups, insurance, retirement plans and visas often ask for age on a specific date rather than today. Work out the gap between your birth date and that date the same way. Some places and traditions count age differently; this calculator uses the international method, where you are 0 at birth and add a year on each birthday.