GUIDE / BOM REVISIONS
Compare two BOM revisions without losing the context.
Start with reliable matching. A report is only useful when it explains which rows were compared and which assumptions remain unresolved.
1. Prepare two flat tables
Keep the previous and updated lists separate. Use one header row and identify columns for part number, quantity, revision, unit and any price information. Remove presentation-only title blocks from the table you intend to import.
Make significant leading zeros explicit text. A cell displayed as 00104 may actually contain the number 104 with a display format. Those are different source representations; the comparison cannot recover zeros that are absent from the stored identifier.
2. Choose a matching key
A part number is often enough for a flat list of unique items. If the same part can appear in several assemblies or locations, include a parent/location field. Do not silently sum duplicate rows unless that aggregation is explicitly part of your own review process.
| Situation | Matching approach |
|---|---|
| Unique part in each file | Part number |
| Part reused across assemblies | Part number plus parent/location |
| Duplicate key within one file | Resolve or review the ambiguous rows |
| Different identifier conventions | Normalize intentionally before comparing |
3. Separate status from field changes
First identify added and removed keys. On matched keys, compare mapped quantities, revisions, descriptions, units and prices. Keep source-row references so a reviewer can inspect the original evidence.
For example, a part with quantity 8 becoming 12 is a matched quantity change. A new retaining clip is an addition. A missing label is a removal. These cases have different review implications, even if they all affect a purchasing handoff.
4. Review numeric and commercial assumptions
Check whether commas are decimal or thousands separators. Do not compare quantities across incompatible units or prices across different currencies as if they were interchangeable. Missing prices should remain unknown.
A known matched-line cost change is not the same as the total cost of the new BOM. Additions, removals, freight, taxes, minimum orders, tooling and supplier terms need their own review.
5. Export the evidence
Share the complete comparison with its assumptions and source rows. If you filter the on-screen report, confirm whether the export contains the full result or only the visible subset. The Parts & Quotes offline edition exports its full report, regardless of the current search or filter. The free browser trial shows results on screen and does not export reports.
In the fictional demonstration, three matched parts change, one is added and one is removed. The known comparable matched-line cost change is $6.00; it is not a complete landed-cost estimate.
Try the BOM comparison example ↗