Date Difference Calculator
Find the exact number of days, weeks, months, and years between two dates.
How to Use
- Pick a start date and an end date.
- Results update instantly in multiple units.
- Toggle "Include end date" to count both boundary dates.
- Use the "Business days" figure for working-day calculations.
When to Use This
- Estimating a project duration where the business-days figure matters more than the raw calendar span between kickoff and the agreed deadline.
- Checking a notice period or contract term, where the include-end-date toggle decides whether the final day is counted or not.
- Working out how long remains until a visa, warranty or subscription expires, reading total days rather than an approximate month figure.
- Counting the gap between two historical dates, since the day count comes from elapsed milliseconds and handles leap years without special cases.
Frequently Asked Questions
About This Calculator
Two dates have more than one honest answer for how far apart they are. The gap between 1 and 3 January is two days if you count the intervals and three if you count the dates themselves, which is why notice periods and rental terms argue about the last day. Calendar months add a second ambiguity, since a month is not a fixed length.
Start and end default to today and 30 days out, and a reversed pair is swapped rather than producing a negative. The day count is the rounded millisecond difference, plus one when include end date is on. Weeks divide that count by 7, months by 30.4375 and years by 365.25, all average lengths, shown to two and four decimals. Business days are counted by stepping through the range one day at a time and skipping Saturdays and Sundays.
Notes & Limits
- The weeks, months and years figures divide the day count by 7, 30.4375 and 365.25, which are average lengths and do not follow calendar month boundaries.
- Business days exclude Saturdays and Sundays only. Public holidays are not deducted here; the site's Date Calculator has a business-days mode that accepts holiday dates.
- Dates are whole days with no time of day, and a start later than the end is silently swapped, so the result is never negative.
- The years-months-days breakdown adds the include-end-date day before borrowing, so it can read one day higher than a plain calendar subtraction.