What is the WEEKDAY Function
The WEEKDAY function returns the day of the week as a number. By default, Sunday is 1 and Saturday is 7, but you can change the starting day with the return_type argument.
Formula: =WEEKDAY(serial_number, [return_type])
Practical Example 1
A2 contains 17-Oct-2026.
Type: =WEEKDAY(A2)
Result: 6 (Saturday with default return_type)
Practical Example 2
Use return_type 2 so Monday is 1.
Type: =WEEKDAY(A2, 2)
Result: 5 (Friday)
Practical Example 3
Get the day name from a number.
Type: =CHOOSE(WEEKDAY(A2), Sun, Mon, Tue, Wed, Thu, Fri, Sat)
Result: the day name
When to Use It
WEEKDAY is used for identifying weekends, for scheduling, for payroll calculations, for creating day-based reports, and for any formula where you need the day of the week.