Bill of materials (BOM)
A bill of materials is a comprehensive list of all components, sub-assemblies, raw materials, and quantities needed to manufacture a product. The BOM serves as master record defining what goes into a product, forming the foundation for procurement planning, production scheduling, inventory management, and cost analysis. BOM accuracy directly affects an organization’s ability to build products correctly and cost-effectively.
Examples
Electronics product BOM: A laptop computer's BOM includes hundreds of line items: display panel, processor, memory modules, storage drive, battery cells, keyboard assembly, enclosure parts, circuit boards, cables, connectors, screws, thermal materials, and packaging. Each item has a part number, description, quantity per unit, and unit of measure.
Multi-level BOM: An industrial machine's BOM shows the top-level assembly, which consists of several sub-assemblies (power unit, control system, frame), each with their own component lists. This hierarchical structure reflects how the product is actually built, with sub-assemblies completed before final assembly.
Configurable product BOM: A vehicle BOM supports multiple configurations with optional features. The base BOM covers standard components while options add or substitute parts based on customer specifications. The BOM system manages this variability.
Definition
BOMs evolved from simple parts lists to sophisticated data structures managed in enterprise systems. Modern BOMs include not just components but also specifications, supplier information, documentation links, and effectivity dates that control when changes take effect.
Different functional perspectives require different BOM views. Engineering BOMs organize components by functional system. Manufacturing BOMs reflect assembly sequence and work station structure. Procurement views show items grouped by commodity and supplier. PLM and ERP systems maintain these views from a common data source.
BOM accuracy is critical. Missing components halt production. Wrong quantities cause shortages or excess inventory. Incorrect specifications result in quality problems. Organizations invest in BOM management processes including change control, version management, and data governance to maintain accuracy.
The BOM connects to many business processes: procurement uses it for sourcing and ordering, manufacturing for production scheduling and work instructions, finance for product costing, and quality for traceability. This central role makes BOM management a foundational capability.
Previous
*GARTNER is a registered trademark and service mark of Gartner, Inc. and/or its affiliates in the U.S. and internationally, and COOL VENDORS is a registered trademark of Gartner, Inc. and/or its affiliates and are used herein with permission. All rights reserved. Gartner does not endorse any vendor, product or service depicted in its research publications, and does not advise technology users to select only those vendors with the highest ratings or other designation. Gartner research publications consist of the opinions of Gartner’s research organization and should not be construed as statements of fact. Gartner disclaims all warranties, expressed or implied, with respect to this research, including any warranties of merchantability or fitness for a particular purpose.