Dynamic calculated fields

Hi everyone,

This is my first post to this forum...

I am designing a spreadsheet consisting of a pivot table that contains various customer data and sales volumes by month. Within the pivot table will be a calculated field (what this post is about) reflecting the average of, say, the past six months of sales volumes.

My challenge is that I would like to create a pair of input cells (begin date and end date) that the calculated fields could reference (the logic would be >=Begin date AND <=End date) and thereby allow adjustments to be dynamically made to the date range used in the calculated field. I have not managed to find a means to do this - any suggestions? Is this realistically possible?

I mocked up the attached file to show what the structure will look like once real sales data has been populated. Also outlined is an alternate that would be workable if what I described above is not feasible.

Thank you in advance. Let me know if you need more information.

Rick