Calendar Week Start/End Dates

See if this works for you greenguy2012 

I don't understand your example above as 3/30/2021 is on a Tuesday, so the start date would be monday, or March 29, and the end would be wednesday, the 31st.
April 1 then is on a thursday, so would be 4/1, and the end of that week would be 4/4, or Sunday.

This is the code:

let
    Source = {Number.From(#date(2021,3,1))..Number.From(#date(2021,5,31))},
    #"Converted to Table" = Table.FromList(Source, Splitter.SplitByNothing(), {"Date"}, null, ExtraValues.Error),
    #"Changed Type" = Table.TransformColumnTypes(#"Converted to Table",{{"Date", type date}}),
    #"Inserted Day Name" = Table.AddColumn(#"Changed Type", "Day Name", each Date.DayOfWeekName([Date]), type text),
    #"Inserted Day of Week" = Table.AddColumn(#"Inserted Day Name", "Day of Week", each Date.DayOfWeek([Date], Day.Monday), Int64.Type),
    WeekStartDate = 
        Table.AddColumn(
            #"Inserted Day of Week",
            "Week Start Date",
            each 
                let
                    varStartDay = Date.StartOfWeek([Date],Day.Monday)
                in
                if Date.StartOfMonth(varStartDay) = Date.StartOfMonth([Date])
                then varStartDay
                else Date.StartOfMonth([Date]),
            Date.Type
        ),
    WeekEndDate = 
        Table.AddColumn(
            WeekStartDate,
            "Week End Date",
            each
                let
                    varEndDay = Date.EndOfWeek([Date], Day.Monday)
                in
                if Date.EndOfMonth(varEndDay) = Date.EndOfMonth([Date])
                then varEndDay
                else Date.EndOfMonth([Date]),
            Date.Type
        )
in
    WeekEndDate

You do NOT need the Day Name or Day of Week number. I used those to see what was going on. What it does is uses the Date.StartOfWeek/Date.EndOfWeek functions forced to use Day.Monday for the first day of the week. If it is in the same month, use the calculation, otherwise use the first/last day of the month to start/end that particular week.

If that isn't right, please provide good data with clear examples per links below.

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Hi greenguy2012 ,

You could also realize it using dax expression:

First create a weeknum column:

Weeknum = WEEKNUM('Table'[Date],2)

Then create 2 columns as below:

Week Start Date = CALCULATE(MIN('Table'[Date]),FILTER('Table','Table'[Weeknum]=EARLIER('Table'[Weeknum])))

Week End Date = CALCULATE(MAX('Table'[Date]),FILTER('Table','Table'[Weeknum]=EARLIER('Table'[Weeknum])))

And you will see:

For the related .pbix file,pls see attached.

Best Regards,
Kelly

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