Are you forecasting or analysing historical data?

If I had historical data, I'd probably tackle this differently. It's purely forecasting

Are you tracking individual units or working with averages?

Averages.

Approximately how many units (per day/week/month/year) are we talking about? Of if you are working with averages, how many categories?

My template is set up for monthly figures.

• Opening
• Produced (per demand and maintaining adequate closing)
• Shipped out (per sales figures)
• Received back (this is per a percentage of the shipped out from previous months)
• Damaged/expired (currently 20% of "Received back")
• Closing

The issue in that calculation is really calculating the cost of sales, given that an item can be shipped out 15 times. Curious if there is a math formula I'm not realizing that could solve the "shipped back" and make the "damaged/expired" units more accurate.

Approximately how many time periods does your model consider?

Monthly, for 5 years.