Dimensional Boxes not Packed as Expected

Overview

On some occasions the products should be packed into boxes in a particular method. However, the products are not packed into the boxes that are expected.

Example

In this example these boxes are defined, each with a box tolerance of 0 and no maximum quantities:

Small – 4″ x 5″ x 5″, max weight 5lb.
Medium – 7″ x 7″ x 7″, max weight 10lb.
Large – 7″ x 7″ x 7″, max weight 18lb.
Extra Large – 20″ x 20″ x 20″, max weight 45lb.

There is one 2″ x 2″ x 2″ product in the cart with a weight of 4lb.

When a quantity of one of this product is in the cart on its own we want the small box to be used. For a quantity of two, the medium box should be used.
When there is a quantity of three of that product in the cart we want one small and one medium box to be used as the carrier has quoted a lower rate than if the large box is used. However, the large box is used instead.

Explanation

When using a quantity of three of the example product in the cart the large box is being favoured over a small box with a medium box because the large box has a sufficient weight capacity for all of the products in the cart and the dimensions are the same as the medium box. There is nothing between these boxes that denotes that the large box should not be used so it will be picked over the combination of one small box with one medium box.

Similarly, if there is a quantity of five in the cart, which is over the volume and weight of the large box then the extra large box will be used as there is sufficient capacity.

Removing the larger boxes from the list of possible boxes for that product will use multiples of the smaller boxes.