Bill of materials (BOM) is a list of the raw materials, sub-assemblies, intermediate assemblies, sub-components, components, parts and the quantities of each needed to manufacture an end item (final product).

It may be used for communication between manufacturing partners, or confined to a single manufacturing plant.

A BOM can define products

as they are designed (engineering bill of materials),

as they are ordered (sales bill of materials),

as they are built (manufacturing bill of materials), or

as they are maintained (service bill of materials).