In this scenario, we want to to ship two types of products, one large and one small. If both products are in the cart, they should ship in one box. We also want to allow any number of Small Items to fit into the Large Box along with the Large Item i.e. the Small Items do not take up any space in the box.
Two Box Definitions have been created, Large Box and Small Box. The Large Item can only be shipped in the Large Box, so we assign that item to that box in Product Information > Individual Shipping Boxes.
The Small Item can be shipped in the Small Box or Large Box and so we add both of those Box Definitions for that product.
When both the Large Item and Small Item are in the cart, we want to be able to ship any number number of Small Items in one Large Box, along with the Large Item.
We can do this by setting the “Max Qty allowed in this Box” to -99.
The -99 value effectively says the small items take up no additional space in the box, however the weight will still increase.
Each carrier has their own maximum weight for packages and so there is the potential to accidentally exceed this maximum weight when using -99.
To prevent this, be sure to create a Box Definition and set its “Maximum Weight per Box” to less than or equal to the carrier’s “Maximum Package Weight”. See screenshots below.
Viewing the Log File
A better understanding of how Dimensional Shipping calculates the usage of boxes can be seen by viewing the log file generated.
The following article explains how to enable logging and view the logs: How do I return logs for Packed Boxes within Dimensional shipping