Date Difference Calculator
Calculate the difference between two dates in days, weeks, months, years, and business days.
About this tool
Enter a start and end date to see the gap between them broken down five different ways at once: total days, total weeks (as a decimal), a months-plus-days breakdown, a full years-months-days breakdown, and business days (weekdays only, excluding Saturday and Sunday). The months and years breakdowns are computed by comparing calendar fields directly rather than dividing by an average day count, so they correctly account for varying month lengths and leap years - the same way you’d work it out by hand, borrowing a month or year when the day-of-month doesn’t divide evenly. If the start date happens to be after the end date, the tool still computes an absolute difference and notes that the order was reversed rather than returning a negative or nonsensical result. Useful for project timelines, calculating someone’s tenure, or figuring out how many working days remain before a deadline. Runs entirely client-side.
Frequently asked questions
It counts every calendar day between the start and end date and excludes any that fall on a Saturday or Sunday, giving a simple weekday count. It does not account for public holidays, since those vary by country, region, and even individual organization, so treat this as a weekends-only business day count rather than a full working-calendar calculation.
Months have different lengths (28 to 31 days) and years vary with leap years, so a calculation like "total days ÷ 30" would drift and produce a slightly wrong answer for most date ranges. Instead, the breakdown compares the actual calendar fields - year, month, and day - directly, borrowing from the next unit when needed, which is the same method you’d use counting on a calendar by hand and always gives an exact result.
The calculator still produces a result - it computes the absolute difference between the two dates and shows a note that the order was reversed, rather than returning a negative number or an error. This makes it forgiving if you swap the two fields by mistake.
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