How to Limit Pre-Order Quantities (Pro)

Limits stop one buyer taking a launch. There are two of them, they work differently, and both can be set globally or per product.

The two limits

Max Quantity Per Order caps a single cart. It counts what is already in the cart plus what is being added.

Max Quantity Per Customer caps a customer’s total across all their pre-orders of that product. It counts what they have already reserved, plus their cart, plus what they are adding.

The second only works for a logged-in customer, because a guest cannot be counted across orders. If it matters, require an account: How to Restrict Who Can Pre-Order (Pro).

Step 1: Set the store-wide limits

Go to Configuration → Checkout.

The two quantity limit fields

Default Max Quantity Per Order and Default Max Quantity Per Customer. Both empty by default, meaning no limit. Zero also means no limit.

Step 2: Save

Press Save Changes. The limits apply to every pre-order product that does not set its own.

Step 3: Override a single product

Edit a pre-order product from Pre-Order → Products.

The product’s own two quantity fields

A product’s own limit wins over the global one whenever it is filled in. So the global fields are the fallback, not a ceiling: a product set to 10 allows 10 even when the store default is 2.

Leave a product’s field empty to inherit.

Step 4: Test the cart limit

Set the per-order limit to 2, then try to reserve 5 on the storefront.

The refusal for a cart over the per-order limit

Nothing is added, and the message names both the limit and the product:

You can reserve up to 2 of Mug BHeart in one pre-order.

Step 5: Test the customer limit

Set the per-customer limit instead, as a customer who already holds reservations of that product, and try to add more.

The refusal for a customer over their total limit

You can reserve up to 3 of Mug BHeart across your pre-orders.

The two messages differ by three words. “In one pre-order” means this cart is too big and a smaller one will go through. “Across your pre-orders” means the customer has reached their total and no cart will go through until something is cancelled. Worth knowing before you answer a support email about it.

Where the limits are enforced

Twice, and both matter.

On add to cart, so the shopper is told immediately.
Again at checkout, so a cart that was built before the limit changed, or in another tab, cannot slip through.

The second check is why a customer can occasionally see an error at checkout for a cart that was accepted earlier.

Limits against stock

These are separate from the Stock figure on the pre-order form.

Stock is how many units exist to promise, across everybody.
The limits are how many any one cart or customer may take of them.

Use both. Stock protects your production run; the limits stop one buyer emptying it.