Date Utility
Age Difference Calculator
Enter two birth dates and get the exact gap between them in years, months, and days. The calculator accounts for month lengths and leap years, and also gives the total in months, weeks, and days. Everything runs in your browser.
Age difference
5y6m5d
The two birth dates are 5 years, 6 months, and 5 days apart. The earlier date is 1990-05-15 and the later date is 1995-11-20.
The same gap in other units
66total months
287total weeks
2,015total days
How to use it
1. Enter the first date
Pick the first person’s date of birth.
2. Enter the second date
Pick the second date of birth. The order does not matter.
3. Read the gap
See the exact difference in years, months, and days, computed instantly.
4. Check other units
Use the totals in months, weeks, and days when you need a single number.
What each number means
| Result | What it tells you |
|---|---|
| Years, months, days | The exact calendar gap, the way you would say an age out loud. |
| Total months | Whole months between the dates, for forms and spreadsheets. |
| Total weeks | Whole weeks between the dates. |
| Total days | Every day counted, including leap days. |
Common questions
How is the age difference calculated?
The tool counts whole years and months first, then the leftover days. It accounts for the real length of each month and for leap years, so a date like February 29 is handled correctly. This is the same method a person uses when saying someone is, for example, 5 years and 3 months older.
Does the order of the two dates matter?
No. You can enter the dates in any order. The calculator sorts them, shows which is earlier and which is later, and always reports the gap as a positive amount.
Why do the total days and the years-months-days not match up simply?
A year is not a fixed number of days and months vary in length, so a gap of one year can be 365 or 366 days. The years-months-days view is the calendar gap, while the total days is an exact count of every day between the two dates. Both are correct; they just answer different questions.
Can I use it for things other than people?
Yes. Any two dates work. Use it for the gap between two events, two anniversaries, or two deadlines, not only birthdays.