Product quantity rules let you control exactly how many units a customer can buy. You can set a minimum (they must buy at least X), a maximum (they can buy at most X), or a step increment (they buy in multiples of X).
Creating a Rule
Go to Rules and click Create rule
Choose the products or variants you want the rule to apply to
Set your limits:
Minimum quantity – The smallest amount a customer can add to cart. Useful for wholesale or bulk-only products.
Maximum quantity – The largest amount allowed per order. Useful for limited stock or fair-use policies.
Step / increment – Forces purchases in multiples (e.g., step of 6 means customers can buy 6, 12, 18, etc.). Great for products sold by the case or pack.
Save the rule
You can combine all three settings on the same rule. For example, minimum 2, maximum 20, step 2 means customers can buy 2, 4, 6, 8… up to 20.
What the Customer Sees
The quantity selector on the product page adjusts automatically – the +/- buttons skip to valid amounts
If a customer tries to enter an invalid quantity, they see an inline message explaining the limit
At checkout, Shopify validates the quantity again so limits cannot be bypassed
Plan
Available on all plans including Free (up to 5 rules). Growth and Advanced plans support unlimited rules.