How age is calculated
Age is counted in whole calendar months from your date of birth, then the remaining days. The calculator finds the latest date that is a whole number of months after your birth date without going past the reference date, and counts the days from there. Months have different lengths, so this is more accurate than dividing a number of days by an average month length.
Month-end and leap-year birthdays
Birthdays near the end of a month need care. Someone born on 31 January reaches one month of age at the end of February, since February has no 31st; on 1 March 2024 they are 0 years, 1 month and 1 day old. Someone born on 29 February 2000 was 23 years, 11 months and 30 days old on 28 February 2024, the day before the 29th came round again.
Totals
As well as years, months and days, the calculator shows your age as a total number of months, weeks and days. Total days count the actual calendar days between the two dates, including leap days.
Dates and privacy
The reference date defaults to today in your own time zone, and you can change it to find an age on any past or future date. Your birth date is personal information; it is processed only in your browser and never sent anywhere.