Dynamic Column calculation based on Slicer Selection

Hi LeranPowerBI

Try the following

1. Create a table called MonthTable consisting of only MonthNames

     MonthNames

     Jan

     Feb

    .....

    Dec

2. Use this Column MonthName from this MonthTable as a slicer for selecting month.

3. In your data table create a measure called SelectedMonthValue

   SelectedMonthValue =  IF(HASONEFILTER(MonthTable[MonthName]),
                                    LOOKUPVALUE((YourTable[Amount]),YourTable[Month],Values(MonthTable[MonthName]))
                                     ,1)

  What this does is finds the value of Amount from YourTable ( data table) for the selectedmonth in the slicer. If no value is selected in slicer it is set to 1.

4. Now the magic

    Create a measure called Relative in YourTable.

    Relative = SUMX(YourTable,Divide(YourTable[Amount],[SelectedMonthValue]))

    What this does is it iterates YourTable row by row and then calculates the relative value for that row.

Sample screen shot with the data provided by you

If this solves your issue, please accept it as a solution and also give KUDOS.

Cheers 

CheenuSing