About this tool
Date Difference is a free, in-browser calculator that measures the gap between two calendar dates and reports it four ways at once: the total number of days, complete weeks plus any leftover days, the total number of whole months, and a years-months-days breakdown.
Pick a start and an end date. If the later date is entered first, the two are swapped automatically so the result is never negative. Both dates are read at local midnight, so only whole days are counted and time of day or daylight-saving shifts never skew the total. The month and year figures follow the calendar, borrowing each month's real length instead of assuming a fixed thirty days, which makes it handy for tracking ages, notice periods, or project spans.
The whole calculation runs in your browser: no uploads, no accounts, no tracking, and it works offline.
Frequently asked questions
Does the order of the two dates matter?
No. If the end date is earlier than the start date, the two are swapped automatically, so the difference is always positive.
Are both endpoints counted?
The result is the number of whole days from the start date to the end date, so consecutive days such as the 1st and the 2nd read as one day rather than two; the end date is not added as an extra day.
Why does the weeks figure include a leftover number?
Weeks are the total days split into complete seven-day weeks plus any remaining days, so 100 days shows as 14 weeks plus 2 days.
How are the years, months and days figured?
That breakdown compares each date's year, month and day and borrows the previous month's real length when the day underflows, so it follows the actual calendar instead of assuming fixed thirty-day months.
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