Age & Date Difference Calculator
Work out an exact age in years, months and days, or the time between any two dates, with total days and weeks and the next birthday.
How it's calculated
The difference is counted the way people count ages:
- Months are counted on the calendar from the start date: the largest number of whole months that fits before the end date. Adding a month to 31 January gives the last day of February.
- Years are 12 of those months.
- Days are whatever is left after the last whole month.
The totals (days, weeks, months) cover the same period. The end date itself is not counted, so 1 to 2 January is one day. The next birthday is the first anniversary of the start date after the end date; 29 February birthdays fall on 28 February in common years.
Frequently asked questions
How are months counted?
On the calendar, not as 30-day blocks. From 15 May to 15 June is one month; from 31 January, one month later is the last day of February.
What about birthdays on 29 February?
In years that aren't leap years, the birthday is counted on 28 February.
Is the end date included?
No. The result is the time from the start date up to the end date, the way ages are normally counted. Add one day if you need both dates included.