BOM Editor

Last updated: June 20, 2026

A bill of materials defines what goes into making a product: the components, sub-assemblies and quantities needed to build one unit of output. It is the recipe that links a finished item back to the raw stock it consumes, and the foundation production and kitting build on.

What you will learn
  • What a bill of materials contains
  • How component quantities scale with output
  • Required versus optional components, and substitutes
  • How a BOM attaches to a stock item
Output product1 unitComponent Ax2Sub-assemblyx1Component Cx4Sub-componentx3A BOM explodes through every level into raw components
A bill of materials is a multi-level recipe of components simplified mockup

Anatomy

A bill of materials has a code, name and description, an output unit and quantity (what one run produces), and a list of component lines. Each component line carries:

  • Unit and quantity – how much of the component one output needs.
  • Quantity mode – how that quantity scales: per output unit, by inversion, or as an absolute amount regardless of run size.
  • Required or optional – whether the component is essential or a permitted extra.
  • Stock mapping – the actual stock item(s) the line draws on; a line can map to more than one, allowing substitutes.

How it behaves

Attaching to an item

A stock item links to its bill of materials, which is what makes the item producible. The BOM's description can also surface on sales documents, so a kit reads sensibly to the customer. A bill runs through New, Confirmed and Cancelled states as it is drafted and approved.

Flattening

A multi-level bill can contain sub-assemblies that are themselves built from components. An allow-flatten setting controls whether those sub-assemblies explode down to raw components or are treated as built items in their own right, which is the difference between buying a sub-assembly ready-made and making it in-house.

Worked example

A gift set is one output unit built from two of Component A, one sub-assembly, and four of Component C; the sub-assembly is in turn three of a sub-component. The bill captures all of it, and Component C's line maps to two interchangeable SKUs so either can be used.

Edge cases and good practice

  • Mark genuinely optional parts optional, so requirement planning does not over-order them.
  • Use multi-stock lines for substitutes rather than separate bills.
  • Choose the quantity mode to match how a component really scales with batch size.

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