When you analyze business days across teams, you need a reliable way to count actual working days in Excel. The NETWORKDAYS function helps you exclude weekends and holidays, giving you precise results for schedules and timelines.
This guide explains how to use NETWORKDAYS effectively and avoid common pitfalls with Vietnamese localization and real project data.
| Function | Syntax | Purpose | Notes |
|---|---|---|---|
| NETWORKDAYS | =NETWORKDAYS(start_date, end_date, [holidays]) | Count working days excluding weekends and optional holidays | Weekend is Saturday and Sunday by default |
| NETWORKDAYS.INTL | =NETWORKDAYS.INTL(start_date, end_date, weekend_code, [holidays]) | Flexible weekend definitions and custom holiday lists | Allows different weekend patterns per country |
| Holiday List | Range or array of dates | Dates to exclude from working days | Can reference a named range or direct dates |
| Weekend Codes (INTL) | 1 to 17, or 7-digit binary string | Define which days are weekend in different regions | For Vietnam, weekend code 7 or "0000011" for Sat+Sun |
Understanding NETWORKDAYS in Excel
NETWORKDAYS is a date and time function designed to calculate the number of whole working days between two dates. It automatically removes Saturday and Sunday, and you can optionally remove specific holidays.
Use this function when you need accurate day counts for project planning, employee tenure, or service level agreements where nonworking days must be excluded.
Basic Syntax and Vietnamese Holiday Setup
Core Parameters
The basic syntax is =NETWORKDAYS(start_date, end_date, [holidays]). Start and end dates are required, while the holiday list is optional but recommended for local accuracy.
Preparing Holiday Data in Excel
Create a clean list of holiday dates, for example in column E, then reference that range in the holidays argument. Name the range for easier maintenance across multiple formulas.
Using NETWORKDAYS.INTL for Custom Weekends
Weekend Code 7 for Vietnam Standard
In Vietnam, the weekend is Saturday and Sunday. In NETWORKDAYS.INTL, you can use weekend code 7 or the binary string "0000011" to explicitly define this pattern.
Flexible Weekend Handling
When teams in different regions share one workbook, use NETWORKDAYS.INTL with custom weekend codes to keep calculations consistent and avoid manual adjustments.
Common Errors and Validation Tips
Incorrect date formats, text strings that look like dates, or holidays outside the date range can produce unexpected results. Always check that inputs are valid Excel dates.
Use DATE or DATEVALUE to build reliable date references, and format result cells as General or Number to avoid misleading date serial numbers.
Best Practices for Day Calculations
Structure your workbook so that date inputs, holiday lists, and results are clearly separated and well documented.
- Use consistent date formats across columns and sheets
- Define named ranges for holiday lists to simplify updates
- Validate start and end dates with ISNUMBER to catch text entries
- Document weekend rules and codes inside the workbook for future users
- Test edge cases such as same-day ranges and ranges that include only holidays
FAQ
Reader questions
How do I count working days for a project timeline with Vietnamese holidays?
Use NETWORKDAYS with your start and end dates, and include a named range that lists Tết and other official holidays to exclude them from the count.
What does it mean when the result is a negative number?
A negative result means the start date is later than the end date; double-check the order of dates in your formula.
Can I use this to handle different weekend rules for international teams?
Yes, NETWORKDAYS.INTL with appropriate weekend codes lets you model various weekend patterns while keeping a single workbook structure.
How do I highlight holidays that fall on weekends in the count?
Keep all holidays in the list; NETWORKDAYS automatically ignores any holiday that already falls on a nonworking day, so no double adjustment is needed.