BOM

What is a BOM?

BOM (Bill of Materials) is a structured list of all raw materials, sub-assemblies, parts and consumables required to manufacture one unit of a finished product. The bill of materials is multi-level — the finished product is made up of sub-assemblies, which are composed of further sub-assemblies, down to the purchased materials at the lowest level.

Example from a metal fabrication company: the BOM for a sofa set contains the frame (3 kg of steel tube, 12 M8 screws, 1 welding labour unit), upholstery (2.4 m of fabric, 1.2 kg of foam) and packaging. MRP derives precise purchasing and capacity requirements from the BOM and sales orders; a cost estimator uses it to calculate the manufacturing cost; and an engineer uses it during change management processes.

Types of bills of materials you will encounter in practice:

• Engineering BOM (eBOM) — from the designer’s perspective
• Manufacturing BOM (mBOM) — from the production perspective, including the routing
• Sales BOM — configuration visible to sales

When it is used

Without a bill of materials, serious production planning, price calculation, or inventory management is not possible. A BOM is essential when creating quotes, calculating margins and during engineering change orders (ECO).

See the Production module, the Warehouse module, and the manufacturing industry page.

Related terms

• MRP — consumes the BOM as an input dataset. See /en/glossary/mrp.
• MES — uses the BOM when dispatching operations to the shop floor. See /en/glossary/mes.
• SKU — each item in the BOM has its own unique SKU. See /en/glossary/sku.

In Modulario

In Modulario the bill of materials is a first-class object in the Production module — it supports multi-level structures, alternative components, versions, and change history. The BOM feeds directly into Warehouse (automatic stock deduction) and Quotes (cost recalculation when material prices change).

When a component in the BOM changes (e.g. new price, alternative supplier, engineering change), versioning preserves the history — the system can show which parts were used to build the unit with serial number XY six months ago. This traceability is required by automotive customers and the pharmaceutical industry.