Shopify collection limit: 3 units across products

Share a three-unit allowance across a Shopify collection. Configure combined quantity and test mixed carts, collection membership and unrelated items.

Your promotion includes products A, B and C. Customers can mix them freely, but the collection total in a cart must not exceed 3 units.

When to use this

Use this when several samples or promotional products share an allowance. It allows combinations without creating bundles or discounts.

Before you begin

Create a promotional collection containing distinct products A, B and C, plus one product outside the collection.

Settings

Open the app home page → All quantity rules → create a rule.

Setting	Example value
Rule name	Promotion collection: combined maximum 3
Rule type	Cart quantity limit
Maximum quantity	3
Calculation	Limit the combined cart quantity of applicable items
Scope	Collections: promotion collection
Timing	Cart interactions and checkout

Steps

1. Open Apps → 订单限购 in Shopify. From the app home page, open 所有数量规则 and click 创建规则.
2. Enter the rule name and thresholds from the settings table. The name is for admin use only.
3. Under 规则应用于, select the scope in the table. For selected products or collections, click 选择产品 or 选择产品系列 and confirm the selected names appear.
4. Set the timing from the table. Under 保存后的状态, select 已启用 and click 创建并启用. When editing an existing rule, click 保存并启用.
5. Return to 数量限制 and turn on 开启数量规则. Confirm 购物车与结账校验 is enabled, using 启用校验 if necessary.
6. Reopen the rule to confirm its thresholds, scope, customer conditions and active state were saved. Run the storefront tests below.

Test your configuration

Each result describes this recipe only. Keep the product scope consistent and verify checkout; other active rules may still block the cart.

Test	Expected result for this scenario
A × 1 + B × 2	Allowed: 3 units
A × 2 + B × 2	Blocked: 4 units
A × 3 + 5 units outside the collection	Allowed by this rule
No items from the collection	Outside this rule’s scope

Products added to this collection later also match. Use Specific products if you want a fixed list instead.

Compare calculation methods in quantity limits.

If results differ

If A × 2 plus B × 2 passes, check that calculation is combined and both products belong to the selected collection.

Use troubleshooting to investigate. Complete the launch checklist before rolling out.