How to limit the total number of items in a Shopify order

Short answer: Cap the total number of units per order — useful when packaging, couriers or inventory can't handle oversized orders. In Checkpost, choose “Maximum items per order” from Templates, adjust the values, test it, then save and enable the rule.

The problem

Packaging, carrier weight limits and stock planning all break when one order takes 200 units. A store-wide cap routes bulk buyers to you directly.

How to set it up

1. Install Checkpost from the Shopify App Store.
2. Open Templates and choose Maximum items per order.
3. Set the maximum number of units.
4. Use Try this rule to test a sample cart, then click Save rule.

The rule

Checkout is blocked when all of these conditions is true:

• Total item quantity is greater than 20

Shoppers see: “Orders are limited to 20 items. Please contact us for bulk orders.” at the top of checkout, in the cart and at checkout.

{
  "name": "Max 20 items",
  "match": "all",
  "conditions": [
    {
      "kind": "number",
      "field": "cart_quantity",
      "op": "gt",
      "value": 20
    }
  ],
  "message": "Orders are limited to 20 items. Please contact us for bulk orders.",
  "target": "cart",
  "runOn": "always"
}

Where this rule works

These are cart and checkout validations, including supported accelerated checkouts. They are current-cart policies; they do not track previous purchases of a SKU. Shopify excludes POS, recurring subscription orders and native pre-order/Try Before You Buy flows from this API. See Shopify's validation compatibility.

Tips

• Set the limit just above your largest normal order.
• Exclude wholesale customers by adding a customer tag condition (has none of wholesale).
• Link to a contact or wholesale form in the message.

FAQ

Does it count gift cards?

Yes, all cart lines count. Add a separate rule if you want gift cards limited differently.

Is there also a limit on different products?

Yes. Use "Number of different items" to cap distinct lines instead of units.

Related rules

Add maximum items per order to your store