Calculating the available quantity of an item is done as follows:

in stock - reservation = available

An item quantity in inventory can be edited by the store.

When the quantity available is negative, this means that there are more reserved items than the total quantity put into inventory. So we see that the inventory has been updated to zero or to an amount less than zero after reservations were made.

The negative inventory scenario happens when you attempt to write off an order item when this item is still reserved by the system. This scenario occurs when you try to decrease the quantity of an item when it was purchased, but the item is still reserved by the system and can not have its stock lowered.

The correct flow predicts that the write-off happens only after the Preparing Delivery status. After this status, the reservation is already recognized. Prior to this, the system will understand that the item being lowered is not the item in reserve, updating the inventory incorrectly.

To adjust it, the item stock must be updated with the quantity of physical items in inventory. This way, the value of the items in stock must be the sum of the available items plus the items that are reserved and that are not yet in the Preparing Delivery status. Te correction can be done by following the steps below:

1. In the VTEX Admin, go to Catalog > Inventory, or type Inventory in the search bar at the top of the page.
2. Click Inventory Management.
3. Search for the SKU you want and click on the search result.
4. In the Update Count column, fill in the value indicated in the description above.
5. Click Save.

When two or more warehouses use the same trade policy, and there is a negative number of items in stock for a given SKU in one of these warehouses, the SKU becomes unavailable for sale, even though the inventory quantity is positive in another warehouse.