How to Create and Read a Bill of Materials in Onshape

What is a BOM?

A BOM is a parts list for a product or assembly. Depending on your project, it may include details such as:

• • Item number
• • Part name
• • Part number
• • Quantity
• • Material
• • Description

For example, a desk lamp BOM might list one base, one arm, two fasteners, and one shade. A clear BOM helps people review the design, prepare drawings, and plan what needs to be made or purchased.

Before you begin

First, create an Assembly in Onshape and insert the parts and subassemblies it needs. Check that the assembly contains the components you intend to include. Give parts clear names and fill in useful properties—especially part numbers and descriptions—so the BOM is easy to understand.

How to create a BOM in Onshape

1. Open the Assembly tab containing your design.
2. Click the BOM table icon on the right side of the graphics area, below the View tools.
3. Onshape generates a BOM from the parts and subassemblies in the assembly.
4. Review the rows and properties. You can edit supported property cells directly in the BOM table; those changes also update the corresponding part or subassembly properties.
5. Add or remove columns to show the information your team needs.

The BOM table is interactive. Hover over a row to highlight its component in the graphics area. Select an item number to locate that component in the Instances list and assembly.

Structured or flattened: which view should you use?

Onshape offers two ways to display the BOM:

• • Structured shows the assembly hierarchy. Subassemblies can be expanded to show their components. Use it when the product’s organization matters.
• • Flattened lists the components as if they were all at the top level. Use it when you want a straightforward parts list without hierarchy.

A small assembly may be easy to read in either view. For a product with several subassemblies, structured view can make it clearer which parts belong together.

How to read a BOM

Each row represents a part, subassembly, or other listed item. The columns provide information about that item. For instance:

The quantity tells you how many instances are required. In a structured BOM, indented rows and expandable subassemblies show the product’s hierarchy. If your table is sorted or its item order has been changed, check that item numbers still correspond to the intended components.

Put the BOM on a drawing

If you need the parts list on a technical drawing, open the drawing and use the BOM table tool to insert BOM data from an assembly. You can choose a flattened or structured table, depending on how much assembly hierarchy you want to show. Onshape also supports balloons that can link drawing callouts to BOM items.

Tips for a dependable BOM

• • Use consistent part names and part numbers.
• • Fill in properties before sharing the BOM.
• • Choose structured or flattened view to suit the people reading it.
• • Review subassembly behavior: a subassembly can appear with its components, as a single line, or as components only.
• • Check the BOM after changing the assembly, since additions or removals affect the list.
• • Include non-modeled items—such as glue or thread locker—when they matter to purchasing or assembly. Onshape supports adding these items through the BOM panel.

A useful parts list, built from your design

Onshape’s BOM starts with the parts in your assembly and brings their properties into one table. With clear names, useful part numbers, and the right view, it becomes easier to understand what a product contains and communicate that information to the rest of the team.

For more details, see Onshape’s guides to Bill of Materials, working with the BOM table, and adding a BOM table to a drawing.