WEEKDAY

Determines the day of the week by returning a representative number.

Syntax of Excel Weekday formula:
=WEEKDAY(serial_number,[return_type])

In words:
=Which weekday is represented(by this date,[if this return scheme is used])

Explanation

In WEEKDAY function the serial_number argument is mandatory which is basically a date or serial number of the date.

Return type argument is optional and not required. If it is left out then “1” will represent Sunday and “7” will represent Saturday.

In many parts of the world week starts from Monday till Sunday. In which case Monday will be treated as “1” and Sunday will be “7”. If this arrangement is desired then return type will be 2

Whereas in some cases week starts from Saturday and ends by Friday. In this case Saturday is treated as “1” and Friday is represented by “7”. If this is desired then return type number will be 16.

Following table summarizes the return type and relevant date representation pattern:

Return_typeNumber returned
1 or omittedNumbers 1 (Sunday) through 7 (Saturday).
2Numbers 1 (Monday) through 7 (Sunday).
3Numbers 0 (Monday) through 6 (Sunday).
11Numbers 1 (Monday) through 7 (Sunday).
12Numbers 1 (Tuesday) through 7 (Monday).
13Numbers 1 (Wednesday) through 7 (Tuesday).
14Numbers 1 (Thursday) through 7 (Wednesday).
15Numbers 1 (Friday) through 7 (Thursday).
16Numbers 1 (Saturday) through 7 (Friday).
17Numbers 1 (Sunday) through 7 (Saturday).

Examples of Excel Weekday Formula

=WEEKDAY(“7/7/2016”) will return 5.
As return type is omitted therefore week is running “1” as Sunday through “7” as Saturday. Considering this it is Thursday

=WEEKDAY(“7/7/2016”,16) will return 6
As week is running from “1” representing Saturday and “7” representing Friday. So 6 is representing Thursday in this scenario.