BOM — Bill of Materials / Bill of Materials
A Bill of Materials (BOM) — in German Bill of Materials — is a structured list of all components, sub-assemblies, raw materials and quantities required to produce one unit of a finished product. The BOM connects engineering, manufacturing and procurement views and feeds MRP, costing and shop-floor execution in the ERP system.
What does BOM mean
BOM is the English-language abbreviation for Bill of Materials. In German-speaking ERP environments the same artefact is called Bill of Materials. Both terms describe the same thing: the hierarchical list that says what goes into what and in what quantity. Whether you read SAP, Oracle, Microsoft Dynamics, Infor or proAlpha documentation, BOM and Bill of Materials are used interchangeably depending on the user-interface language.
The BOM is the most-referenced master-data artefact in any production ERP: MRP reads it to compute net requirements, costing uses it to roll up product costs, sales-order configuration evaluates it to resolve variants, shop-floor execution consumes against it. A wrong or missing BOM cascades into wrong purchase orders, wrong production plans and wrong cost calculations — usually noticed weeks later when the variance reports come in.
BOM types in brief
- Engineering BOM (EBOM): design-time structure from CAD, organised by functional grouping
- Manufacturing BOM (MBOM): production-time structure with alternatives, phantoms, packaging and shop-floor sequence
- Sales BOM: customer-facing view, often a flat list of selectable options
- Service BOM: spare-parts structure for maintenance and warranty work
- Configurable BOM (super-BOM): parametric structure that resolves to a specific variant at order time, central to engineer-to-order and configure-to-order manufacturing
Multi-level BOMs nest sub-assemblies into a tree — 8–12 levels are typical for complex machinery. The detailed structural and quality discussion lives on the canonical entry: see Bill of Materials — Bill of Materials.
BOM in MRP and procurement
MRP (Material Requirements Planning) walks the BOM tree to compute gross and net requirements per level. Homeing from a sales forecast or production plan at the top level, MRP explodes through every sub-assembly, deducts existing stock and open purchase orders, applies lead times and order quantities and produces planned purchase orders and production orders at the bottom levels. Wrong BOM quantities directly cause over- or under-ordering — one of the most common reasons for MRP credibility crises in mid-market manufacturing.
Related Topics
Frequently Asked Questions
Is BOM the same thing as Stückliste?
Yes — BOM is the English-language abbreviation, Stückliste is the German term. Both describe the same artefact: a hierarchical list of components, sub-assemblies and quantities required to produce one finished product. ERP systems use the terms interchangeably depending on the user-interface language.
Where in the ERP does the BOM live?
The BOM is master data, typically maintained in the product / material module of the ERP and synchronised with PLM (Product Lifecycle Management) for the engineering view. It is read by MRP for net requirements, by costing for product-cost calculations, by sales-order configuration for variant resolution and by shop-floor execution for material consumption.
Can the same product have several BOMs?
Yes, and it is common. The same finished product typically has an EBOM (engineering view from CAD/PLM), an MBOM (manufacturing view with alternatives), a sales BOM (customer-facing options) and a service BOM (parts list for maintenance). ERPs maintain these as separate views with cross-references. For configurable products a super-BOM captures all possible options with rules that resolve to a specific variant at order time.