ShipStation will deduct inventory when you create a label for an order if the following conditions are met:
The order contains an item you have set initial stock counts for.
Inventory tracking is enabled in the Inventory Settings.
The item does not have the Do Not Track option set in its product details.
ShipStation will always deduct the inventory from the warehouse linked as the Inventory Source in the selected Ship From Location. If a product exists in more than one location within that Inventory Warehouse, ShipStation will deduct from the first location listed in the Product Details Inventory section.
You may find that you need to move inventory between locations periodically to ensure your counts are accurate. Review the Update Stock Levels article for more details.
If you attempt to create a label for an order with a higher quantity than available inventory for a product, you will get an alert like this one that reads:
Click Admin Override if you still wish to ship this order.
Selecting this option will ignore your inventory levels entirely - meaning, no stock will deduct from your existing inventory levels. Use the steps above to manually adjust the levels if you need to.
If you use alias SKUs or advanced product types, review the information below to understand how your product records will interact with your internal inventory in ShipStation.
Parent Products are non-buyable, "umbrella" products that exist to group variants for reporting and to push product-level settings to their variants. Since it's not possible to buy a parent product, they can't be associated with inventory units.
Variant products are products under a Parent "umbrella" and can be configured with inventory, just like Standalone products. Inventory will be deducted from the individual variant products when you ship them.
Variant products will be nested under their Parent product in the Products grid. They will also display individually in the Inventory section of your Products tab. Parent products will not appear in the Inventory section.
As you ship the Variant products, ShipStation will deduct inventory from the Variant, and the Parent stock counts will decrease accordingly.
Product Aliases can be assigned to either Standalone or Variant products (but not Parent products).
When orders import with an SKU that is an alias of either a Standalone or Variant product, ShipStation deducts stock from the master SKU the aliased SKU is mapped to.