MS Excel: WEEKDAY function determine the day of the week from any date

The WEEKDAY function in Excel returns a number representing the day of the week for a given date. It's a vital tool in scheduling, reporting, task management, and conditional formatting, especially when you need to identify weekends or group data by weekdays.

For example, if you want to filter out weekends or flag deadlines that fall on Mondays, WEEKDAY makes it possible with just one formula.

Syntax

=WEEKDAY(serial_number, [return_type])

Arguments:

Argument	Required	Description
serial_number	✅ Yes	The date you want to find the weekday for. Can be a date value or a reference.
return_type	❌ No	A number (1–3, 11–17) that defines which day is considered the start of the week. Default is 1.

Return Type Options

Return Type	Week Starts On	Sunday =	Monday =
1 (default)	Sunday	1	2
2	Monday	7	1
3	Monday	6	0
11–17	Custom starts (Mon–Sun)	Adjusts accordingly	—

Examples

Example 1: Basic Weekday Calculation

=WEEKDAY(DATE(2025,5,4))

Result: 1(If return_type is omitted, Excel assumes Sunday = 1)

Example 2: Weekday Starting from Monday

=WEEKDAY("04/05/2025", 2)

Result: 7(May 4, 2025 is a Sunday; 2 makes Monday = 1)

Example 3: Use with IF to Flag Weekends

=IF(WEEKDAY(A2, 2) > 5, "Weekend", "Weekday")

Flags any Saturday (6) or Sunday (7) as "Weekend".

Sample Table

Date	Formula	Return Type	Result	Interpreted As
02/05/2025	=WEEKDAY(A2)	1 (default)	1	Sunday
03/05/2025	=WEEKDAY(A3, 2)	2	6	Saturday
05/05/2025	=WEEKDAY(A4, 2)	2	1	Monday

Notes

• Excel stores dates as serial numbers starting from January 1, 1900 (serial number 1).

• If the input date is invalid, WEEKDAY returns a #VALUE! error.

• Use TEXT(date, "dddd") to return the full name of the weekday instead of a number.

Related Functions

Function	Description
TEXT()	Format date to show full weekday name
TODAY()	Returns current date
NOW()	Returns current date and time
WORKDAY()	Returns a date excluding weekends and holidays
NETWORKDAYS()	Calculates working days between two dates

Summary Table

Feature	Description
Function Name	WEEKDAY
Purpose	Returns the day of the week
Argument Required	Yes (date input)
Customizable Start	Yes (via return_type)
Return Value	Integer (1–7 depending on config)
Introduced In	Excel 2003+

Conclusion

The WEEKDAY function is indispensable for time-based analysis in Excel. It helps you quickly evaluate the day of the week, automate logic for weekends, and build smarter date-aware systems. With its flexible return types, you can match any calendar model you need.