Start with actual movements
Inventory management becomes reliable when each entry, sale, return and breakage has a rule. Choose a reference per salable variant: size and color are as important as the model. Note where the physical inventory is located and who can correct it. An overall figure in a spreadsheet is not enough if the product exists in stores and online.
Set a reservation
Decide when a unit stops being available: payment, pickup confirmation, or team validation. Check what happens to a canceled order and a returned but unchecked product. Test three cases with only one unit remaining; this is where the gaps become visible.
Check a category every week
Choose ten important references and compare displayed quantity, physical quantity and recorded sales. Correct the cause of a discrepancy before changing the number. Track shortages that prevented a sale and frozen items. The goal is a promise of availability that the team can keep, not a perfect picture on paper.
Source: https://help.shopify.com/en/manual/products/inventory.
