Age calculator
Calculate your exact age in years, months and days from your date of birth.
How age is calculated
The calculator subtracts the date of birth from the chosen reference date (today by default), and adjusts the result to express it in complete years, months and days:
years = year(reference) − year(birth)
If the day of the month of the reference date is earlier than the day of birth, one month is subtracted and the days of the previous month are added; if the resulting month is negative, one year is subtracted and 12 months are added. This gives the exact age in years, months and days, plus the total number of days lived.
Worked example
A person born on March 15, 1990, whose age is calculated as of September 8, 2026, is 36 years, 5 months and 24 days old, equivalent to 13,322 days lived.
Frequently asked questions
- How is exact age in years, months and days calculated?
- The date of birth is compared with the reference date, and the difference is calculated in complete years, adjusting months and days depending on whether the day or month of the reference date comes before that of the birth date.
- Can I calculate my age on a date other than today?
- Yes, you can change the 'Calculate age on date' field to any future or past date after your birth date to find out how old you would be or were at that time.
- What happens if the date of birth is after the reference date?
- The calculator shows no result, since the reference date must be equal to or later than the date of birth.
- How is the total number of days lived calculated?
- The date of birth is subtracted from the reference date in milliseconds, then divided by the number of milliseconds in a day (86,400,000), rounding down.
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