Pivot Table Custom Formula

I would like to add a custom formula in a pivot table to calculate a weighted average. Anyone have any ideas?

Originally Posted by MatthewFlinchem

I would like to add a custom formula in a pivot table to calculate a weighted average. Anyone have any ideas?

Okay, so I searched and found the answer but my numbers are not coming out.

This is my calculated field. "AVG PPB"
=SUMPRODUCT('Pieces Per Bundle','Total Order Quantity' /'Pieces Per Bundle' )/SUMPRODUCT('Total Order Quantity' /'Pieces Per Bundle' )

The pieces per Bundles represent the number of units is a single pack per line. Total order quantiy represents what it reads. On my worksheet where I put this formula in it looks like

=SUMPRODUCT($A7:$A40,B7:B40/$A7:$A40)/SUMPRODUCT(B7:B40/$A7:$A40)

And it works. A is my Pieces Per Bundle and B is my Order Quantiy. But when I convert this over to the pivot table formual abov it does not work.