Set up inventory tracking (Shopify admin)
Before you can view or adjust inventory levels for a product, you need to set up inventory tracking for the product. After tracking is set up, an inventory adjustment history is available for 90 days.
From your Shopify admin, go to Products.
Click the name of the product that you want to track.
If the product has variants, then click the variant that you want to track.
In the Inventory section, check Track quantity.
If you want to allow customers to purchase the item when it's out of stock, then check Continue selling when out of stock.
In the Quantity section, enter the quantity information for each location.