BOM (Bill of Materials)
Definition
A BOM (Bill of Materials) is the complete, structured list of every component and material required to build a product, together with quantities and reference designators. It is the master record that engineering, procurement, and manufacturing all rely on.
Why it matters
The BOM is where sourcing begins. Buyers procure against it, and lifecycle and compliance checks are run line by line across it. A single obsolete or allocated part on a BOM can stall an entire build, which is why monitoring a BOM against change and discontinuation notices, and identifying cross-references early, is core supply-chain risk work. Accurate manufacturer part numbers on every line make that work reliable.
Related terms
- MPN (Manufacturer Part Number): the identifier that makes each BOM line sourceable.
- Cross-Reference (Alternate Part): the fix when a BOM line goes obsolete.
3E Technology lets you search any BOM line by part number to find every supplier that carries it. See the component sourcing guide.
Frequently Asked Questions
What is a BOM?+
A BOM (Bill of Materials) is the complete, structured list of every component, part, and material needed to build a product, along with quantities and reference designators. It is the master document that procurement, engineering, and manufacturing all work from.
Why is the BOM central to component sourcing?+
Every sourcing and obsolescence task starts from the BOM. Buyers source against it, teams run lifecycle and compliance checks against it, and a single obsolete or allocated line on the BOM can hold up an entire build. Keeping the BOM clean and monitored is the foundation of supply-chain risk management.
Related Resources
MPN (Manufacturer Part Number)
An MPN is the unique identifier a manufacturer assigns to a component. Here's why the manufacturer part number is essential to accurate sourcing.
Cross-Reference (Alternate Part)
A cross-reference is a functionally equivalent replacement for a component. Here's why cross-referencing is often the fastest fix for an obsolete part.
EOL (End of Life)
EOL, or End of Life, is a manufacturer's notice that a component will stop being produced. Here's what it means for sourcing and how to respond.
Component Sourcing: A Practical Guide for Buyers
How component sourcing works: the four supplier channels, a step-by-step sourcing workflow, how to vet suppliers, and where to find sources others miss.
Find the suppliers you need
Search 105,000+ vetted parts suppliers in one query. Free tier includes 5 unlocks — no card required.
Start searching