Set up inventory tracking
Accurate inventory on your Shopify store helps customers when they're trying to place an order. Before you can view or adjust inventory levels for a product, you need to set up inventory tracking for that product. When you track inventory for a product in Shopify, you can view the history of inventory for that product for up to the most recent 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.
If a product's inventory quantity is tracked using inventory apps, then its quantities will be allocated only to that app location. You can change the locations products are assigned to.