The web store allows users to order fractional quantities of an item.

Enable Fractional Quantities Globally

To achieve this, you need to activate Allow Fractional Quantities and also set the number of decimal places. For example, if a user could order 1.25 units of an item, then you would need to set Fractional Quantities Decimal Places to 2.

These settings are located in System > Features. You can activate it for B2B and B2C/guest users.

Enable Fractional Quantities at the Product Level

Once you have enabled the global setting, you will also need to specify which products are eligible for fractional quantities.

Navigate to Catalog > Products and Edit the product in question.

Once in the product, locate the setting for Enable Fractional Quantity and check the box to enable it.

Now your product can be purchased in fractional quantities: