Total Stock
What the business says it has overall.
Track Total Stock, optional Shelf Stock, purchases and stock movements while keeping billing independent. Recorded inventory can reach zero and the sale still completes.
Total Stock is all recorded physical inventory for the item. Shelf Stock is the portion currently placed on the selling shelf. Available Off Shelf is calculated as max(Total − Shelf, 0).
What the business says it has overall.
What is currently available on the selling shelf/display.
Recorded stock not currently represented on the shelf.
A completed sale reduces Total Stock and Shelf Stock, each independently floored at zero. If recorded stock is already zero, billing simply continues and stock remains zero.
Purchase adds to Total Stock only. Returns with Restock add to Total Stock only. Shelf Refill changes Shelf Stock without creating a new purchase.
Goods enter the business → Total Stock increases.
Existing stock moves to the selling shelf → Shelf Stock increases.
Returned goods restore Total Stock but are not automatically placed on shelf.
Start with normal billing. Turn on inventory, Shelf QR, Scan & Buy, online ordering, purchases and additional billing stations when they create value for your business.