What is a business days calculator?
A business days calculator counts how many working weekdays fall between two dates. A business day is any day from Monday to Friday; Saturdays and Sundays are treated as non-working days and are left out of the total. This is useful for estimating delivery windows, invoice due dates, project deadlines and any process that runs on a standard five-day week rather than on calendar days.
Enter a start date and an end date, and the calculator returns the number of business days in the range, counting both the start date and the end date when they are weekdays.
How does it work?
The calculator walks day by day from the earlier date to the later date. Each day is checked against the calendar: if it is a Saturday or a Sunday it is skipped, and every remaining Monday-to-Friday day adds one to the total. Because the counting is inclusive, both the first and the last day are counted when they are weekdays. The order of the two dates does not matter — the calculator always measures the span between them.
Formula
There is no single closed-form expression, but the idea is simple:
Equivalently, count only the days whose weekday is Monday through Friday, inclusive of both endpoints.
Worked examples
Example 1: A single work week
From Monday, January 1, 2024 to Friday, January 5, 2024:
There are no weekend days inside this range, so the answer is 5 business days.
Example 2: Crossing a weekend
From Monday, January 1, 2024 to Monday, January 8, 2024:
The range contains eight calendar days, but Saturday, January 6 and Sunday, January 7 are excluded:
The result is 6 business days.
Example 3: Two full weeks
From Monday, January 1, 2024 to Monday, January 15, 2024 there are three Mondays plus Tuesday-to-Friday of the two intervening weeks:
Business days at a glance
| Start (2024) | End (2024) | Calendar days (incl.) | Weekend days | Business days |
|---|---|---|---|---|
| Jan 1 (Mon) | Jan 5 (Fri) | 5 | 0 | 5 |
| Jan 1 (Mon) | Jan 8 (Mon) | 8 | 2 | 6 |
| Jan 1 (Mon) | Jan 15 (Mon) | 15 | 4 | 11 |
Notes
- This calculator counts a standard Monday-to-Friday week and does not remove public holidays. If your schedule needs to skip specific holidays or use a six-day work week, the working days calculator offers those options.
- To measure the plain calendar span instead — every day, weekends included — use the days between dates calculator.
- Counting is inclusive here, so a start and end on the same weekday returns 1. Definitions differ between tools, so check whether a given calculator includes the end date before comparing results.
FAQ
Are weekends counted as business days?
No. Saturdays and Sundays are always excluded. Only Monday through Friday count toward the total.
Does this calculator include both the start and end date?
Yes. The counting is inclusive: if both endpoints are weekdays, they are both counted. For example, Monday to Friday of the same week is 5 business days.
How many business days are in a normal week?
Five — Monday, Tuesday, Wednesday, Thursday and Friday.
Does it account for public holidays?
No, this tool only removes weekends. To subtract specific holidays, use the working days calculator, which lets you enter a list of holiday dates.
Does the order of the dates matter?
No. Whether you put the earlier date first or second, the calculator measures the span between the two dates and returns the same number of business days.