Business Day Calculator
Add business days to a start date to find the end date — weekends are skipped automatically.
What Is Business Day Calculation and Why Is It Needed?
Business day calculation finds the number of weekdays between two dates, or the end date reached by adding a set number of business days to a start date. Unlike calendar day counting, it excludes weekends.
For situations like project deadlines, legal notice periods, payment due dates or official applications, the result is measured in "business days" rather than "calendar days". Missing this distinction can cause you to miscalculate the actual end date by several days.
How to Use
Inputs
Two inputs are sufficient: Start date (the day the process begins) and the number of business days to add. For best results the start date should fall on a weekday.
Formula and Logic
Each day is stepped through one by one from the start date. Days numbered Sunday (0) and Saturday (6) are not counted; only Monday–Friday days are added to the counter. The loop stops when the target business day count is reached. The result shows the end date, total calendar days and weekends skipped.
Example Scenario
If a project delivery period starting on 15 April 2026 is 10 business days, when is the end date?
| Parameter | Value |
|---|---|
| Start date | 15 April 2026 (Wednesday) |
| Business days to add | 10 |
| Weekends skipped | 4 days (2 weekends) |
| End date | 29 April 2026 (Wednesday) |
| Total calendar days | 14 |
Because 4 of the 14 calendar days are weekends, the actual end date is 29 April; writing "25 April" by counting on a calendar would be incorrect.
How to Interpret Results
The tool returns three values: end date, total calendar days and weekends skipped. The end date is the date that can be used directly in contracts or official correspondence.
Total calendar days gives the actual number of days between the two dates; this value provides an approximate reference for periods without public holidays. Weekends skipped shows the "idle" days in your plan.
Tips for Accurate Results
- 01
Select a weekday as the start date; a weekend entry starts counting from the following Monday.
- 02
Subtract public holidays from the business day count yourself; the calculator only skips weekends.
- 03
For court, enforcement or administrative deadlines, check which specific day the relevant law uses as a reference.
- 04
If you work in different countries, you may also need to account for that country's public holiday calendar.
Frequently Asked Questions
The business day calculator automatically excludes weekend holidays and adds the entered number of business days to the start date to calculate the end date. Remember that you need to adjust the result yourself for public holidays.