Key takeaways
- A spreadsheet BOM works fine for a small number of simple, single-level products with components and BOM-lines tracked as two linked sheets.
- It breaks down once a sub-assembly is reused across multiple products, since updating it means editing every copy by hand.
- Cost rollup and automatic stock deduction on a completed build are the two things a spreadsheet cannot do on its own.
- Migrating is a CSV export/import of the same components and BOM-lines structure, not a rebuild from scratch.
Free multi-level BOM template
A working example with a components sheet and a BOM-lines sheet, showing a real multi-level structure (a finished good built from sub-assemblies, each with their own component list).
What the template covers, and what it doesn't
| Works fine in a spreadsheet | Needs dedicated BOM software |
|---|---|
| A small number of simple, single-level products | A sub-assembly reused across multiple parent BOMs |
| Manually calculating one product's cost once | Automatic cost rollup whenever a component price changes |
| Tracking what a build should consume, on paper | Automatic stock deduction when a build actually completes |
| A handful of components per product | Deep multi-level nesting with cost rolling up through every level |
What actually breaks first
1. Reused sub-assemblies
The same sub-assembly used in two products means two copies to update by hand whenever a component or quantity changes — and they quietly drift apart.
2. Cost rollup
A spreadsheet formula can sum costs once, but every price change means re-checking every product that uses that component, at every level.
3. Stock deduction
A spreadsheet BOM doesn't know when a build actually happened — inventory has to be adjusted manually to reflect what was really consumed.
Migrating without starting over
Moving off a spreadsheet is a CSV import of the same two-sheet structure — components and BOM-lines — not a rebuild. See free bill of materials software for how multi-level BOM authoring and cost rollup work once components are imported, or how to create a bill of materials if you are structuring one for the first time.
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