Understand this tool
Plan with configurable working days
- What the concept means
- A business day is a calendar date accepted as working under a specified workweek and holiday set.
- Why it exists
- Count working dates in a range or move forward or backward by a chosen number of working days.
- When to use it
- Planning schedules with a known workweek and a manually supplied list of relevant holidays.
- What the result means—and does not mean
- The result follows only the selected weekdays, holiday list, endpoint choices, and mode; it is not an official deadline ruling.
Business calendars are conventions
Saturday and Sunday are common weekend days but not universal. A business-day calculation is only reproducible when the working-week set, holiday list, and endpoint rules are stated.
In add/subtract mode the starting date is a reference point, not automatically the first counted new business day. In range mode each endpoint can be included or excluded independently.
Worked example
A week with one custom holiday
Count a Monday-to-Sunday range using a Monday-to-Friday workweek and one Friday holiday.
- Example input
- 2026-07-13 to 2026-07-19; Mon–Fri; holiday 2026-07-17; include both endpoints.
- The range contains seven calendar dates.
- Monday through Friday provide five possible working dates.
- Friday 2026-07-17 is removed as a custom holiday.
- Saturday and Sunday are classified as two weekend dates.
Example result: 4 business days, 2 weekend days, and 1 holiday.
A holiday that already falls on a non-working weekday is not deducted twice.
Key concepts
Key concepts
- Business day
- A calendar date selected as a working weekday and not listed as a holiday.
- Working week
- The weekdays that count as working dates for this calculation.
- Weekend day
- Any weekday not selected in the working week, even if it is not Saturday or Sunday.
- Custom holiday
- A supplied date excluded when it would otherwise be a working date.
- Include start
- Whether the starting date itself can be counted in range mode.
- Include end
- Whether the ending date itself can be counted in range mode.
Method or process
How the process works
Business calendars are conventions
Saturday and Sunday are common weekend days but not universal. A business-day calculation is only reproducible when the working-week set, holiday list, and endpoint rules are stated.
In add/subtract mode the starting date is a reference point, not automatically the first counted new business day. In range mode each endpoint can be included or excluded independently.
Compare the concepts
Calendar days and business days
| Count | Includes | Depends on |
|---|---|---|
| Calendar days | Every date in the interval | Endpoint rule |
| Business days | Selected weekdays minus holidays | Workweek, holidays, and endpoint rule |
Common mistakes
Common mistakes
- Deducting a holiday twice when it already falls on a non-working day.
- Forgetting to check whether the start and end dates are included.
- Assuming every country and workplace uses a Monday-to-Friday week.
Edge cases and limits
Edge cases and limits
- If the end precedes the start, range mode orders the two dates before counting.
- Any weekday can be configured as working or non-working.
- A negative amount in add/subtract mode moves backward.
- Add/subtract mode begins moving after the starting date.