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Business Days Calculator

Count the business days (Monday to Friday) in a number of calendar days from a start date, less the holidays you enter.

By Christopher FloiedPublished Updated

Range: 1 – 31. Whole numbers only

The day of the month for the start date.

Range: 1 – 12. Whole numbers only

The start month (1 = January through 12 = December).

Range: 1 – 9999. Whole numbers only

The year of the start date. Starts at this year.

Range: 1 – 3650. Whole numbers only

The number of calendar days in your date range.

Range: 0 – 50. Whole numbers only

Number of public holidays that fall on weekdays within the range.

Results

Business Days

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Full Weeks

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Non-Working Days

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Holidays Excluded

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How to Use This Calculator

1

Enter your input values

Fill in all required input fields for the Business Days Calculator. Follow the units and input format printed next to each field. Where a unit selector is available, choose the units that match your data.

2

Review your inputs

Double-check that all values are correct and match the units or format shown for each field. Incorrect units are the most common source of calculation errors and can produce results that are off by factors of 2, 10, or more.

3

Read the results

The Business Days Calculator computes the output in your browser and displays the results, with units clearly labeled, as soon as they are ready — no data sent to a server.

4

Explore parameter sensitivity

Try adjusting individual input values to see how the output changes. This is a quick and effective way to develop intuition about how different parameters influence the result and to identify which inputs have the largest effect.

When to Use This Calculator

  • •Use the Business Days Calculator when you need accurate results quickly without the risk of manual computation errors or unit conversion mistakes.
  • •Use it to verify calculations made by hand or in spreadsheets — an independent check can catch errors before they lead to costly decisions.
  • •Use it to explore how changing input parameters affects the output — a quick way to develop intuition and identify the most influential variables.
  • •Use it when collaborating with others to ensure everyone is working from the same numbers and applying the same assumptions.

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About Business Days Calculator

The Business Days Calculator determines how many working days fall within a given calendar period, excluding weekends and holidays. This is essential for project management, shipping estimates, legal deadlines, financial settlements, and payroll calculations. Many contracts and regulations specify deadlines in business days rather than calendar days, making accurate counting critical. The calculator accounts for full weeks, partial weeks, and allows you to subtract public holidays that fall on weekdays. It is particularly useful for international business where holiday schedules vary between countries.

The Math Behind It

A standard business week consists of 5 working days, Monday through Friday, with Saturday and Sunday as the weekend. In a typical year there are about 250 business days in the United States: 260 to 262 weekdays, less the 11 federal holidays (other countries have their own). The ratio of business to calendar days is approximately 0.714, meaning roughly 71 percent of days are working days. This ratio is widely used for quick estimates in project planning. Legal deadlines often specify business days: for example, a 10-business-day notice period is actually 14 calendar days if no holidays intervene, but could be 16 or more calendar days if holidays are included. Financial markets use the T+2 settlement convention, meaning trades settle 2 business days after the transaction date. In software development, sprint planning typically uses business days, with a 2-week sprint containing 10 working days. Understanding the distinction between business and calendar days prevents costly miscalculations in legal compliance, project delivery, and financial planning.

Formula Reference

Business Days Formula

Business Days = (Full Weeks x 5) + weekdays among the Remaining Days - Holidays

Variables: Full Weeks = floor(Calendar Days / 7); Remaining Days = Calendar Days mod 7, counted from the start date's weekday (the start date included); Holidays = weekday holidays

Worked Examples

Example 1: 30 calendar days with 1 holiday

A project spans 30 calendar days starting on a Monday, with 1 public holiday falling on a weekday.

Step 1:Full weeks = floor(30 / 7) = 4 weeks
Step 2:Remaining days = 30 - 28 = 2 days
Step 3:Business days from full weeks = 4 x 5 = 20
Step 4:The 2 remaining days are a Monday and a Tuesday: 2 business days
Step 5:Total business days = 20 + 2 - 1 holiday = 21 days

There are 21 business days in the 30-calendar-day period.

Example 2: Quarterly planning period

A fiscal quarter of 91 calendar days (13 weeks) with 2 public holidays on weekdays.

Step 1:Full weeks = floor(91 / 7) = 13 weeks
Step 2:Remaining days = 91 - 91 = 0
Step 3:Business days from full weeks = 13 x 5 = 65
Step 4:Total business days = 65 - 2 holidays = 63 days

The quarter contains 63 business days for planning purposes.

Common Mistakes & Tips

  • !Forgetting that holidays falling on weekends do not reduce business days (they are already non-working).
  • !Confusing business days with weekdays; business days exclude both weekends and holidays.
  • !Not verifying which holidays are observed in the relevant jurisdiction.
  • !Assuming all months have the same number of business days; they range from 20 to 23 depending on the month and year.

Related Concepts

Date Calculator

Calculate total calendar days between two dates.

Time Card Calculator

Track hours worked across business days for payroll.

Frequently Asked Questions

How many business days are in a month?

A typical month has between 20 and 23 business days, depending on how weekends and holidays fall. On average across a year, there are about 21 business days per month. February has 19 or 20 in the US, after Presidents' Day, while months with 31 days and favorable weekend alignment can have up to 23.

Do business days include the start date?

It depends on the context. In legal settings, the start date is often excluded and counting begins the next business day. In project management, the start date is typically included. This calculator counts the business days in the range that starts on the start date you enter, including it, and runs for the number of calendar days you give, so adjust your inputs to your convention.

How many business days are in a year?

A year has 260 to 262 weekdays (Monday to Friday): 365 days is 52 weeks and 1 day, and a leap year has one more day. In the United States the 11 federal holidays bring that to 249 to 251 business days, for example 250 in 2025 and 2026. The exact number depends on how weekends and holidays fall; other countries have different holidays.

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