Aged Inventory Calculation

I am trying to break current stock on hand into ageing buckets based on transactional data. The monthly ageing buckets I am after are 0-3, 4-6, 7-9,10-12, 12+.

As an example I may have 10000 units on hand with 5000 in the 0-3Month bracket, 3000 in the 4-6Month bracket and 2000 in the 7-9Month Bracket.

Unfortunatly our system doesnt tag inventory with an age so I need to be able to count back in incoming/outgoing transactions to place into correct buckets. Thoughts are to put a tranasactional age against each date and then use some form of IF formula withen each of the aged bucket cells to placed the inventory value.

I have attached a basic sheet showing the type of data I have, along with what what I am trying to achieve.

Stephen

Issue Solved, Thanks Gak