MS Excel: WORKDAY.INTL function for advanced workday calculation with custom weekends

While the standard WORKDAY function in Excel helps calculate dates by skipping weekends and holidays, WORKDAY.INTL offers greater flexibility. It allows you to define custom weekend days, which is essential for organizations or countries where weekends differ (e.g., Friday–Saturday or Sunday only).

Ideal for global teams, factories running alternative shifts, or regional calendars — this function helps tailor project schedules and calculations precisely to real-world work patterns.

Syntax

=WORKDAY.INTL(start_date, days, [weekend], [holidays])

Arguments:

Argument	Required	Description
start_date	✅ Yes	The starting date for your calculation.
days	✅ Yes	Number of working days to add (positive) or subtract (negative).
weekend	❌ No	A code or string defining which days are weekends.
holidays	❌ No	Optional range of holiday dates to exclude.

Weekend Parameter Options

You can define the weekend in two ways:

Numeric Weekend Codes:

Code	Weekend Days
1	Saturday, Sunday (default)
2	Sunday, Monday
3	Monday, Tuesday
4	Tuesday, Wednesday
5	Wednesday, Thursday
6	Thursday, Friday
7	Friday, Saturday
11	Sunday only
12	Monday only
...	... up to 17

Binary String (7 characters):

Each character represents a day starting from Monday (left) to Sunday (right). Use:

• 1 to mark as weekend

• 0 to mark as workday

Example:

• "0000011" → Saturday and Sunday are weekends (default)

• "1000001" → Monday and Sunday are weekends

• "0000000" → No weekends at all

Examples

Example 1: Add 10 workdays, skip Friday–Saturday weekends

=WORKDAY.INTL(DATE(2025,5,1), 10, 7)

Result: May 15, 2025(Skips Fridays and Saturdays)

Example 2: Custom weekend (Sunday only)

=WORKDAY.INTL("2025-05-01", 10, 11)

Result: May 13, 2025(Sunday is the only non-working day)

Example 3: Use holiday exclusions

Assume C2:C3 = May 8 and May 9 (holidays)

=WORKDAY.INTL(DATE(2025,5,1), 10, 1, C2:C3)

Result: May 19, 2025(Skips weekends and holidays)

Sample Table

Start Date	Days	Weekend Code	Holidays	Formula	Result
01/05/2025	10	7 (Fri–Sat)	—	=WORKDAY.INTL(A2, B2, C2)	15/05/2025
01/05/2025	10	"0000001"	08/05, 09/05	=WORKDAY.INTL(A3, B3, C3, D3:D4)	19/05/2025

Notes

• days = 0 returns the same day if it's a working day, or the next working day.

• You must format the result as a date (Ctrl + 1 → Date format) for readability.

• Binary strings must always be 7 characters, from Monday to Sunday.

Related Functions

Function	Use Case
WORKDAY	Basic workday calculation (Sat–Sun weekends)
NETWORKDAYS.INTL	Count number of workdays between two dates with custom weekends
TODAY()	Dynamic current date

Summary Table

Feature	Details
Function Name	WORKDAY.INTL
Purpose	Add/subtract workdays with custom weekends
Default Weekend	Saturday–Sunday (code = 1)
Custom Weekends	Yes – via numeric code or binary string
Holiday Support	Yes
Output Type	Date (serial number, formatted as date)
Excel Version	Excel 2010 and later

Conclusion

The WORKDAY.INTL function gives you granular control over business-day logic by allowing flexible weekends and holiday exclusions. It’s a must-have for users dealing with international business, non-standard workweeks, or production schedules.