In the inventory settings, you will see the options to select either in stock supply or total supply. Your choice will determine how the inventory valuation report is calculated. For example, if you choose in stock supply, we will take the number of in stock units you have available for a specific SKU and multiply it by the default cost you set for that SKU.
The main difference is In Stock Supply includes only those items available for shipping.
Total Supply: The total item quantity a seller has in Amazon's fulfillment network supply chain. This includes inventory available for shipping, inventory in inbound shipments, and inventory being transferred between Amazon fulfillment centers.
In Stock Supply: The item quantity a seller has in Amazon fulfillment centers that is available for shipping.