Date Difference & Working Days Calculator
Days, weeks, months and working days between two dates, with your own days off.
How to use the Date Difference & Working Days Calculator
- Pick a start date and an end date. The gap in days, weeks, months and years appears at once.
- Tick "Count the end date as well" when both ends belong to the period, as for a hotel stay or a contract.
- Choose which weekdays are your weekend and list your own days off, one date or range per line, to get the number of working days.
- Use the lower part to add or subtract working days, calendar days, weeks, months or years from any date.
About this tool
Two dates, one gap: how many days until the deadline, how many weeks the project ran, how many months are left on the lease. This calculator gives all of those from the same pair of dates and treats the gap the way a calendar does, so 31 January to 1 March is one month and one day whether or not February has 29 days that year.
The working-day count is built around your own week rather than a built-in holiday table. Choose which days are the weekend (Saturday and Sunday to begin with, but a Friday and Saturday weekend or a four-day week work just as well) and paste the days off that apply to you: public holidays, closure days, leave. A range such as 2026-08-03 to 2026-08-14 covers a whole break in one line, and the list stays in this browser for next time.
The second calculator goes the other way: start from a date and move by a number of working days, calendar days, weeks, months or years. Ten working days after a Friday skips both weekends and any day off in between, which is exactly what a delivery promise or a payment term needs.
Frequently asked questions
Is the end date counted?
Not unless you tick "Count the end date as well". By default the gap from 1 January to 2 January is one day, and working days run from the start date up to but not including the end date. With the box ticked, Monday to Friday of one week counts as five working days instead of four.
Why are there no public holidays built in?
Holiday dates differ by country, region, employer and year, and a wrong built-in list would quietly spoil the count. Typing your own days off takes a minute and gives a result you can trust, and the list is kept in this browser so you only do it once.
How do I enter the days off?
One per line with the year first, like 2026-12-25, or a range written as 2026-12-24 to 2026-12-31. A note after the date is fine. Lines that cannot be read are listed with their line number, and numbers like 25/12/2026 are refused because the day and month order would be a guess.
What happens when I add a month to the 31st?
The result stops on the last day of the shorter month: 31 January plus one month is 28 February, or 29 February in a leap year. Adding days or weeks is always exact, and adding working days skips every weekend day and day off on the way.
Do my dates leave this device?
No. The counting is done by this page inside your browser. The only things stored are your weekend choice and your days-off list, in local storage on this device, so they are ready next time.