Supply Chain
Preparing a Bill of Materials for the DPP
At what resolution should a bill of materials be kept for a Digital Product Passport? Material-level breakdown, weight-based shares, trims and coatings.
The composition fields of a Digital Product Passport are fed directly by your bill of materials. The problem: most BOMs were built for purchasing and costing, not for material declaration.
Three levels of BOM
| Level | Content | For a passport |
|---|---|---|
| Purchasing BOM | Supplier line items, price | Insufficient |
| Production BOM | Components and quantities | Partly sufficient |
| Material BOM | Material types and weight shares | The level required |
The target for a passport is the third level.
Calculating shares
Composition shares are usually weight-based. Practical rules:
- Record the net weight of each component (excluding scrap).
- Get the material breakdown within each component from the supplier (fabric: 95% cotton, 5% elastane).
- Multiply by weight and sum; the total should converge on 100%.
- Record the reason for any deviation (moisture, coating, measurement tolerance).
Frequently missed items
- Trims: buttons, zips, snaps, labels, sewing thread.
- Coatings and finishes: water repellent, flame retardant — may need a hazardous substance declaration. See DPP for chemicals.
- Adhesives and fillings: especially in footwear and furniture.
- Packaging: not part of the product BOM but may need separate declaration. See packaging DPP and PPWR.
The electronics case
Electronic BOMs can run to thousands of lines. The practical approach is threshold-based declaration: materials above a weight threshold are declared individually and the rest grouped, while critical raw materials and hazardous substances are declared regardless of threshold. See DPP for electronics.
Variant management
Different colours and sizes of one style have different weights and sometimes different materials. Two options:
- Representative variant: model the highest-volume variant and derive others parametrically (must be declared).
- Variant-level BOM: more accurate, more expensive.
See choosing granularity.
Frequently asked questions
My supplier will not give the fabric breakdown.
Labelling law already requires a fibre composition declaration, so the data must exist. Anchor your request in that obligation. See collecting data from suppliers.
Do scrap and waste belong in the BOM?
Not in the composition declaration, which describes the finished product — but they do matter in the carbon calculation. See how to calculate a PCF.
Should the BOM live in ERP or PLM?
What matters is that it is single and structured, not where it sits. See PLM and PIM for DPP.
