Sum by week

[S Oberlander]

In my excel sheet column A is a list of dates, column B is total sales volume for that day, I need totals by week at the end of every week
so in column C I have this formula:

=WEEKNUM(A2,1)

and in column D I have:

=IF(WEEKDAY(A2,1)=7,SUMIF(C:C,C2,B:B),"")

Is there any way to use just one formula for this?

 

[Fluff]

Try

=IF(WEEKDAY(A2,1)=7,SUMIFS(B:B,A:A,">"&A2-7,A:A,"<="&A2),"")