WEEKDAY
Applies to: 
Calculated column
Calculated table
Measure
Visual calculation
Returns a number from 1 to 7 identifying the day of the week of a date. By default the day ranges from 1 (Sunday) to 7 (Saturday).
Syntax
WEEKDAY(<date>, <return_type>)
Parameters
| Term | Definition |
|---|---|
| date | A date in datetime format. Dates should be entered by using the DATE function, by using expressions that result in a date, or as the result of other formulas. |
| return_type | A number that determines the Return value: Return type: 1, week begins on Sunday (1) and ends on Saturday (7). numbered 1 through 7. Return type: 2, week begins on Monday (1) and ends on Sunday (7). Return type: 3, week begins on Monday (0) and ends on Sunday (6).numbered 0 through 6. |
Return value
An integer number from 1 to 7.
Remarks
In contrast to Microsoft Excel, which stores dates as serial numbers, DAX works with dates and times in a datetime format. If you need to display dates as serial numbers, you can use the formatting options in Excel.
You can also type dates in an accepted text representation of a date, but to avoid unexpected results, it is best to convert the text date to a datetime format first.
When the date argument is a text representation of the date, the function uses the locale and date/time settings of the client computer to understand the text value in order to perform the conversion. If the current date/time settings represent dates in the format of Month/Day/Year, then the string, "1/8/2009", is interpreted as a datetime value equivalent to January 8th of 2009. However, if the current date/time settings represent dates in the format of Day/Month/Year, then the same string would be interpreted as a datetime value equivalent to August 1st of 2009.
Example
The following example gets the date from the [HireDate] column, adds 1, and displays the weekday corresponding to that date. Because the return_type argument has been omitted, the default format is used, in which 1 is Sunday and 7 is Saturday. If the result is 4, the day would be Wednesday.
= WEEKDAY([HireDate]+1)