How to Create a BOM (Bill of Materials)

What Is a BOM (Bill of Materials)?

A bill of materials is a list of parts and items required to create the final physical product. It includes the specifications for all related materials, including components, pieces, assemblies, and parts.

What to Include in a Bill of Materials?

There are several components to each piece listed in the bill of materials. Include the following ten categories in your bill of materials to keep it organized and professional

BOM Level

Each component belongs somewhere on the BOM structure, categorizing each piece within the tree-like hierarchy. For example, a handle might be part of your finished product, but some sub-components make up your handle, namely the steel grip and the connecting bolts and nuts.

Part Number

Each component also has a part number to easily identify it, consisting of letters, numbers, or a combination of both. Make sure you don’t create multiple part numbers for your component so you can quickly reference it in the future.

Part Name

Another important identifier is the part name. The key to this step is ensuring the title is simple but descriptive!


Sometimes, you haven’t fully developed a particular part. In these cases, you can identify what “phase” of the process it is in. Perhaps you are still building or testing the component before you include it in the final product? If so, using identifying terms like “Design Phase” or “Unapproved” can help streamline progress on a project.


Like the part name, the description must be simple and clear. However, you should provide much more details. You will use it to distinguish the component from other similar pieces of the finished product.


Of course, you must note how many of each component or piece you need for your product’s assembly.

Unit of Measure

Along with the description, measurements help distinguish components, ensuring exact production quantities to eliminate waste. Standard measures like centimeters, grams, and tabs are common.

Procurement Type

In this section, note where the component came from, including the manufacturing or procurement process. Whether bought from a manufacturer or made in-house, this helps to keep material handling organized and efficient. 

Reference Designators

You only need reference designators if a product contains PCB assembly (printed circuit board assemblies) or electrical components. It usually includes a combination of numbers and letters, and it details where on the physical board it is attached. PCBAs can be single or multilayer boards and can be a costly component for the finished product. 

BOM Notes

Your notes could be a variety of things, from upcoming changes and essential references to suggestions.

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