Quantity rules Free

Quantity rules control how many of something a customer may buy. The free edition covers product and category scope: a minimum, a maximum, a step (sold in multiples of), and a default quantity.

Setting a rule on one product

Open the product, go to Inventory, and use the StoreMaster quantity fields. Each field tells you what it currently inherits, so leaving it empty is unambiguous — empty means inherit, and the description says what will be inherited.

Setting a rule for a category

Use StoreMaster → Quantity to create a rule targeting a category. Category rules inherit to subcategories.

How overlapping rules resolve

When a product and its category both say something, StoreMaster resolves them into one answer rather than letting the last one win:

• the effective minimum is the highest applicable minimum;
• the effective maximum is the lowest applicable maximum;
• steps must have a common solution — 4 and 6 from the same starting point combine to 12;
• the most specific default wins, unless it would be invalid, in which case it is corrected to the first valid quantity.

If a set of rules leaves no quantity a customer could order — a minimum above a maximum, or a step that lands past the maximum — that is reported rather than shipped. A health check under Diagnostics tells you which products are affected.

Where it is enforced

Everywhere a quantity can arrive: the quantity box on the product page, add to cart, updating the basket, the basket and checkout re-check, and the Store API that the Cart and Checkout blocks use. The number input’s min and step attributes are a courtesy; the enforcement is on the server.

Lines are re-checked at basket and checkout, not only when they were added — a rule you change today applies to a basket someone filled yesterday.

The message a customer sees

Customer-facing messages say what to do: the required minimum, the allowed increment, the maximum. They never name a rule, an internal id or a policy.