To calculate working days between a start date and a deadline, count only the business days between them—usually Monday through Friday—and exclude weekends. If your organization observes holidays, exclude those too.

The exact result depends on whether you include the start date, the deadline, or both. Decide that rule before calculating, especially for project schedules, invoices, and contractual deadlines.

Working Days vs. Calendar Days

Calendar days include every day, including Saturdays and Sundays. Working days usually include only Monday through Friday.

For example, from Monday, March 2 to Friday, March 13:

• Calendar days: 12
• Weekdays: 10
• Working days: 10, if there are no holidays

If a public holiday falls within that period, the working-day total is lower.

Basic Calculation Method

Use this process:

1. Write down the start date and deadline.
2. Count each weekday between them.
3. Exclude Saturdays and Sundays.
4. Subtract any recognized non-working holidays.
5. Decide whether to include the start date, deadline, or both.

Example

Start date: Monday, March 2
Deadline: Friday, March 13

The weekdays are:

Mar 2, 3, 4, 5, 6
Mar 9, 10, 11, 12, 13

There are 10 working days.

If March 9 is a public holiday, there are 9 working days.

Include or Exclude the Start Date?

This is the most common source of confusion.

For project planning, many teams count the number of working days available after the start date and including the deadline. For leave requests or attendance records, they may include both dates.

Always state the rule clearly, such as: “The deadline is 10 working days from the start date, excluding weekends and public holidays.”

Calculate Working Days in Excel

Excel provides the NETWORKDAYS function.

If the start date is in cell A2 and the deadline is in cell B2, use:

=NETWORKDAYS(A2,B2)

This counts both the start date and the deadline if they are weekdays.

Exclude holidays

Put holiday dates in a separate range, such as D2:D10, then use:

=NETWORKDAYS(A2,B2,D2:D10)

Example

Make sure the result cell is formatted as a number, not a date.

Calculate Working Days in Google Sheets

Google Sheets uses the same NETWORKDAYS function.

=NETWORKDAYS(A2,B2)

To exclude holidays:

=NETWORKDAYS(A2,B2,D2:D10)

You can also use WORKDAY to find a deadline a certain number of working days after a start date.

For example, to find the date 10 working days after the date in A2:

=WORKDAY(A2,10)

To exclude holidays:

=WORKDAY(A2,10,D2:D10)

Calculate Working Days Manually

For short periods, count the weekdays directly.

Example: March 2 to March 20

Weekdays:

Week 1: Mar 2, 3, 4, 5, 6
Week 2: Mar 9, 10, 11, 12, 13
Week 3: Mar 16, 17, 18, 19, 20

Total: 15 working days.

If March 17 is a holiday:

15 - 1 = 14

There are 14 working days.

Account for Holidays and Local Schedules

Working days are not the same everywhere. A “working day” depends on the country, company, industry, and sometimes the specific team.

Check whether the following apply:

• Public holidays
• Company closure days
• Weekend pattern, such as Friday–Saturday weekends in some countries
• Part-time schedules
• Religious or regional holidays
• Industry-specific shutdown periods

For a contract or formal deadline, use the definition of “business day” written in the agreement. If it is not defined, ask for clarification before relying on an assumption.

Calculate a Deadline From Working Days

If you know the start date and the number of working days allowed, calculate the deadline by counting forward through weekdays.

Example

Start date: Monday, March 2
Allowed time: 5 working days

Count:

Day 1: March 3
Day 2: March 4
Day 3: March 5
Day 4: March 6
Day 5: March 9

If the start date is not counted, the deadline is March 9.

If the start date is counted as day 1, the deadline is March 6.

Common Mistakes to Avoid

Counting weekends as working days

Unless your organization explicitly works weekends, exclude Saturday and Sunday from a standard working-day calculation.

Forgetting holidays

A holiday can change the deadline by one or more days. Always use an accurate holiday calendar for the relevant location and organization.

Using calendar days when the agreement says business days

“10 days” and “10 business days” can produce very different deadlines. Read the exact wording in contracts, policies, and payment terms.

Starting the count on the wrong day

Clarify whether the start date counts as day 1. This is especially important for legal notices, payment terms, and project deadlines.

Ignoring time zones

For remote teams or international contracts, confirm which time zone determines when a task is submitted or a deadline ends.

Quick Reference

Count only the working days that apply to your schedule, exclude weekends and recognized holidays, and clarify whether the start date counts. For reliable results, use NETWORKDAYS to calculate the time available or WORKDAY to calculate a future deadline.