How it works
- 01
Enter a date of birth
Enter the day, month and year. Any year from 1 to 9999 works.
- 02
Pick the age-at date
Today by default. Change it to measure age at a past or future date.
- 03
Read the totals
See your exact age, the total months, weeks and days, and how far away your next birthday is.
How the age is counted
The calculator counts calendar age in whole units. It finds the complete years first, then the complete months since your last birthday, then the days left over. So an answer like 35 years, 5 months and 16 days is more exact than a decimal age based on an average year.
Months are 28 to 31 days long, and leap years add a 29 February. So you cannot turn months and years into a fixed number of days without losing accuracy. The calculator counts the leftover days from the last monthly anniversary and never borrows them from the month before. That is why 31 January to 1 March reads as one month and one day.
- Range
- Any two dates from year 1 to year 9999.
- Leap years
- Real calendar dates, not an average year of 365.25 days.
- Totals
- Months, weeks, days, hours, minutes and weekdays elapsed.
- Time zones
- The dates are calendar dates, so time zones never shift them.
Other uses
The same sum works for the time between any two dates, such as how long a project ran or how far off an anniversary is. Swap dates puts the two dates the other way round. The Born and As of rows show the weekday of each date.
A 29 February birthday has no match in three years out of four. In those years this tool uses 28 February. Countries set different rules, and some use 1 March instead. The page tells you when it has used 28 February.