Date & time
Business days calculator
Contracts, notice periods and SLAs are almost always counted in working days, which is not the same as dividing by seven.
Why working days are counted separately
Notice periods, payment terms, court deadlines and service level agreements are usually written in business days, precisely so that a weekend or a public holiday does not eat into the time available. "Within 10 business days" and "within 10 days" can differ by four days or more.
Dividing calendar days by seven and multiplying by five gets close but is wrong at the edges, because the answer depends on which day of the week you start. A 10-day span starting Monday contains 8 working days; the same span starting Friday contains 6.
Inclusive or exclusive
The counting mode here is inclusive of both endpoints, which is the convention most contracts use when they say "between 1 and 30 September". If your agreement counts from the day after the start, subtract one from the result.
The adding mode works the other way and is exclusive of the start: adding 1 business day to a Friday gives the following Monday, not Friday itself. That matches how deadlines are normally expressed — "you have 10 business days from today" means today does not count.
Holidays are not automatic
There is no universal holiday calendar. Public holidays differ by country, by region within a country, and by year — many move with Easter or shift when they fall on a weekend. Rather than ship a list that would be wrong for most visitors and stale within a year, this calculator takes the dates you supply.
Paste them one per line or comma-separated in ISO format. A holiday falling on a Saturday is ignored automatically, since it was never a working day, and the calculator reports how many of your listed dates actually reduced the count.
Working weeks that are not Monday to Friday
The Sunday-to-Thursday option covers much of the Middle East, where Friday and Saturday form the weekend. Monday-to-Saturday suits retail, construction and manufacturing schedules in many countries. Getting this wrong is a common source of dispute in cross-border contracts, where each side assumes their own week.
A note on time zones
All arithmetic here is done in UTC. That is deliberate: JavaScript's local-time dates shift by an hour across daylight saving boundaries, and a date anchored at midnight can slide into the previous day, dropping a full day from a long count. Working in UTC removes the problem entirely.
Common questions
Does this include the start and end dates?
In "between" mode, yes — both endpoints are counted, which matches how most contracts word a date range. In "add" mode the start date is not counted, so adding one business day to a Friday gives the following Monday.
Why do I have to enter holidays myself?
Because public holidays vary by country, by region, and by year, and several move with Easter or shift when they land on a weekend. A built-in list would be wrong for most visitors and out of date within a year.
What if a holiday falls on a weekend?
It is ignored, since that day was never a working day. The calculator shows how many of your listed holidays actually reduced the count, so you can see when this has happened.
Can I count backwards from a deadline?
Yes. In "add" mode enter a negative number of business days and the calculator steps backwards, skipping weekends and holidays the same way.