How to use it
- Pick the date of birth.
- The second date is today by default. Change it to see the age on any other day.
- Read the age in years, months and days, and the totals below it.
How the age is counted
The calculator counts whole months from the birth date and turns them into years and months, then counts the days left until the second date. When a month is shorter than the birth day, the anniversary moves to the month’s last day: one month after 31 January is 28 February (29 in a leap year).
Total days are the plain difference between the two dates; total weeks are those days divided by 7, rounded down. Dates are calendar days, so time zones and daylight saving time do not change the result.
Worked example
Born on 15 May 1990, age on 3 November 2026:
- whole months: 36 years and 5 months bring us to 15 October 2026;
- from 15 October to 3 November there are 19 days;
- so the age is 36 years, 5 months and 19 days, or 13,321 days in total;
- the next birthday, 15 May 2027, is 193 days away. 15 May 1990 was a Tuesday.
Where an exact age is useful
Forms and contracts that ask for age in full years, school and sports age groups that use a cut-off date, retirement and pension dates, and of course counting down to a birthday.