It's difficult to give a definitive answer without seeing how your data is
laid out and some example data. But I suspect that either a variation of a
SUMPRODUCT() [Excel 2007, 2003 and earlier] or SUMIFS() [Excel 2007 only]
formulas may provide a solution.

"Rob Williamson PSU" wrote:

I am looking for a way to calculate a Weeks of Supply number based on
inventory level as well as a time-phase demand row WITHOUT just using the
average of the demand.

Anyone?