Minimum purchase quantity defines the minimum number of product units that a user needs to add to the shopping cart to make the checkout option available. A minimum purchase quantity is set on a per-product basis, and displays on the related product details page in the storefront provided the Wholesale add-on is installed and enabled.
A store admin can set the minimum product purchase quantities via the Inventory Tracking tab of the chosen product's details:
Select a product to edit on the product listing page (Catalog -> Products) of your store Admin area.
Open the Inventory Tracking tab of the product details page.
On the page that opens, use the "Minimum purchase quantity" section to specify the minimum purchase quantity for every available membership level and for "all customers" (users without a membership):
Finally, click Update to save the changes.
By default, the minimum purchase quantity value is 1 (one) for every customer regardless of the membership. When a store admin changes this value to any different, this info displays on the storefront's product details page. If a store admin changes the minimum purchase limit for a particular customer membership, only the users with this membership will see the changes:
Suppose a customer adds a product with the changed minimum purchase quantity value to the cart directly from any product listing page (home page, category page, etc.). In that case, it adds to the cart in the amount specified as the minimum purchase quantity value for this product in the Admin area.