Everything you need to know about openBOM BOM types

Terminology can be tough. Place two engineers in the same room and they will likely give you three options on what to call the same thing. I’m often asked about the different types of BOMs you can create and manage using openBoM.  I’ll describe what they are.

For the purposes of this article, I will use a fictitious product: a simple bike. The picture below shows you the overall product view. Apologies for the drastic oversimplification; of course a real bike has many more parts.

There are three types of BOMs in openBoM: single level, part list, and multi-level. In the following pictures, I will show you the differences between BOMs as well as how openBom generates them from CAD data.

  1. Part list.

A Part list one is the most commonly used type of BOM to order parts for your product. openBoM can create a BOM which represents all the parts collected from all assemblies and sub-assy levels.

The challenge with this type of BOM is to exclude all purchased and phantom assemblies, otherwise the Part list will have wrong parts and wrong quality. Bam!!  Not good.


  1. Single level BOM.

Single level BOMs are created from any assembly in a CAD Top Level Assembly. The BOM grabs all subassemblies and parts from a specific level and places them on the list.

Single levels are useful for creating a BOM list to place in a drawing for a specific assembly.

  1. Multi-level BOM.

A multi-level BOM is one which creates a hierarchy of parts, assemblies, and sub-assemblies. In openBoM, it is a set of single level BOMs representing each level. You can view and manage them separately. They are connected by Name and/or Part Number references.

You can navigate through these types of BOMs using the openBoM multi-level BOM view and see all the Parts.

We are not done working on BOM types and improving openBoM. If you think of or see something that will help us improve how openBoM BOM types work, please let me know

Oleg, 3 June 2017