Direct answer
To count business days between two dates, start with the full date range, exclude weekends, then subtract holidays or custom non-work dates that apply.
You also need to decide whether the start date and end date are included. Some rules include both endpoints, while others begin counting the next business day.
For a standard Monday through Friday calendar, Saturdays and Sundays are not business days. Holidays usually do not count if the relevant organization is closed.
Formula and example
The practical formula is: business days = weekdays in the range minus holidays or custom non-work dates.
The correct count depends on the calendar you are using: employer, court, bank, school, delivery, and personal work calendars can differ.
Comparison table
| Date range | Weekend rule | Holiday rule | Counting note |
|---|---|---|---|
| Monday to Friday | Exclude weekend | No holiday | Usually 5 business days if both endpoints count |
| Friday to Monday | Exclude Saturday and Sunday | No holiday | Usually 2 business days if both endpoints count |
| One full calendar week | Exclude weekend | No holiday | Usually 5 business days |
| Week with a holiday | Exclude weekend | Holiday closed | Usually one fewer business day |
Step-by-step calculation
Key checks
- Choose the start date and end date before deciding whether either endpoint should be included.
- Remove Saturdays and Sundays when using a standard Monday-Friday business calendar.
- Subtract holidays, office closures, or custom non-work dates that apply to the specific organization.
- Check whether the rule says business days, workdays, court days, banking days, school days, or delivery days.
- Use a calculator for deadlines, follow-ups, or date ranges where a one-day mistake would matter.
Worked example
A useful example is easier to trust when each assumption is visible. The sample below follows the same order you should use for your own numbers.
Key checks
- Choose the start date and end date before deciding whether each endpoint should count.
- Exclude Saturdays and Sundays when using a standard Monday-Friday business calendar.
- Add holidays, office closures, or custom non-work dates when they affect the deadline.
What can change the result
Inclusive versus exclusive counting is the biggest hidden issue. Some deadline rules begin counting the day after an event.
Holidays and custom closure dates can change the result even when the weekend rule is obvious.
If the count affects a legal, HR, school, shipping, or contract deadline, check the rule before relying on the number.
Common mistakes to avoid
Key checks
- Do not assume business days and personal workdays are always the same.
- Do not forget holidays or custom closure dates when the organization is not open.
- Do not mix inclusive and exclusive counting in the same deadline calculation.
- Do not use a standard Monday-Friday calendar for a team that works weekends or rotating shifts.
- Do not rely on calendar-day counts when the instruction specifically says business days.
When to use the calculator
Use the work days calculator for follow-up deadlines, PTO planning, project timelines, notice periods, delivery expectations, and date ranges affected by weekends or holidays.
A good workflow is to answer the narrow question first, then open Work Days Calculator when you need to test different inputs or carry the result into another work decision.
Open Work Days Calculator