# How does Dimensional Shipping work out which individual box items fit into?

The boxes have three fields that allow you to specify how many of which items can fit into each of the boxes. These are found under “Individual Shipping Boxes” in the product Information.

The extension mathematically ca​​lculates which box(es) to use based on all of the products in the cart. The quantity fields are “hard limits” on the boxes for the respective SKU.

“Max QTY allowed in this Box” – This is how many of that item can physically fit in the box. Think of it like the fraction of space that the item takes up; if 10 items can fit then one item takes up 1/10th of the space.

“Min QTY box valid from” – This is the minimum quantity that the product needs to go into the box. So, if this is set to 5 then the box will only be used if there are 5 of this product in the cart.

When left as the default, -1, the extension will take the box into consideration when the product is in the cart.

“Max QTY box valid upto” – This is the maximum quantity that is allowed be assigned to the box for the current product (regardless of other products in the cart). When this quantity is exceeded the box is excluded for that product altogether (I.E.: multiples of that box will not be used). This does not prevent the box from being assigned to other products in the cart.

E.g.: If the “Max QTY allowed in this Box” is 10, the “Max QTY box valid upto” is 20 then one box will be used when there is a quantity <= 10, two boxes if > 10 and <= 20 and the box will be excluded > 20.

Bear in mind that the quantities specified in the “Individual Shipping Boxes” do not override the maximum quantities or weights specified in the “Dimensional Box Manager” section.