What Is a BOM in Fashion? Every Material. Every Line. One List.
The bill of materials lists every material and component in a style, with quantities and costs. Here is what goes in a fashion BOM, how to build one, and how to keep it accurate as styles change.
A bill of materials (BOM) in fashion is the complete list of every material and component needed to make one style, with the supplier, colour, quantity and cost of each. It covers the main fabric and everything else: lining, thread, zips, buttons, labels, hangtags and packaging. The factory uses it to buy materials, and the brand uses it to cost the product.
When a line is missing from the BOM, the factory picks its own, so the sample arrives with the wrong buttons or no care label.
Key takeaways
- A BOM lists every material and component in a style, not only the main fabric.
- Each line should name the item, supplier, reference, colour, placement, quantity per unit and cost.
- The BOM drives three things: what the factory buys, what the product costs and what the sample looks like.
- Colourways change BOM lines, so each colour version needs its own colour references.
- BOMs go wrong when they live in a separate spreadsheet from the tech pack.
One list. Five teams depend on it.
Think of it as the shopping list and the price list for one style, in the same place:
- Sourcing. The factory and your sourcing team know exactly what to buy, from whom and in what quantity.
- Costing. Multiply the quantity per unit by the unit price for each line, add the lines up, and you have the material cost of the style. Labour, overheads, duty and freight come on top.
- Sampling. The factory builds samples from the BOM. Missing trims are a classic reason samples come back wrong.
- Production and quality. In bulk production, quality teams check the finished product against the approved BOM.
- Compliance and traceability. Fibre content, origin and certificates for each material often sit next to the BOM line.
Six sections. Eight details on every line.
Most apparel BOMs group their lines into sections:
- Fabrics. Shell (main) fabric, contrast fabric, lining, interlining and fusing.
- Trims. Zips, buttons, snaps, drawcords, elastic, tapes, eyelets and embroidery thread.
- Sewing thread. Thread type and colour, especially where it differs from seam to seam.
- Labels. Brand label, size label, care and content label, and country-of-origin label.
- Packaging. Hangtags, polybags, tissue, stickers and cartons.
- Artwork and finishes. Prints, embroidery, washes and treatments, where they are bought in or charged as components.
For each line, record:
- Item name and the supplier's reference (article number)
- Supplier name
- Description: composition, weight, width or size
- Colour, for each colourway
- Placement on the product
- Quantity per unit and unit of measure (metres, pieces, cones)
- Unit price and currency
- Notes, such as a wastage allowance or minimum order quantity
Five BOM problems teams tell us about. And the fix for each.
Thread, care labels and polybags were left off, so the factory substituted its own.
Give every small item its own line.
The quantity had no unit, so "2" could mean two metres or two pieces.
Write the unit of measure next to every quantity.
The BOM had one colour for every colourway.
Give each colourway its own colour reference on every dyed or coloured line.
The BOM was updated in one file and the tech pack in another.
Keep the BOM inside the tech pack, with one version for both.
A supplier swapped a trim during sampling, and nobody updated the BOM before bulk.
Record every substitution on the BOM line the day it is agreed, with who agreed it.
Follow one jacket from sketch to BOM
Imagine Hana, a product developer at a womenswear brand, building the BOM for a jacket in navy and sage:
- Every visible component on the flat sketch becomes a line, down to the hangtag and polybag.
- Two colour columns, navy and sage, carry a reference on every line.
- Prices go on every line, and the material cost is checked against the target.
- The BOM goes to the factory inside the tech pack, as one version.
Start from the sketch. Finish with a version.
- Start from the approved design. Work from the flat sketches. Every visible component on the sketch should become a BOM line.
- List the fabrics. Include weight and width for each. The factory needs both to calculate how much fabric each garment uses.
- Add every trim. Walk the garment from top to bottom: neckline, closures, pockets, cuffs and hems.
- Add labels and packaging. These are the lines most often forgotten, and the ones that hold up shipment when they are.
- Set quantities. Fabric consumption usually comes from the pattern marker (the layout of pattern pieces on the fabric). Trims are counted per unit. Add a wastage allowance where your suppliers expect one.
- Add colour for each colourway. One style in three colours may need three zip colours and three thread colours.
- Add prices and total the cost. Compare the material cost with the target cost from your line plan.
- Attach it to the tech pack and version it. Every change after the first send gets a new version and a note on what changed.
Components as rows. Colourways as columns.
A colourway is one colour version of a style. The simplest way to handle colourways in a BOM is to list components as rows and colourways as columns. For a jacket in navy and sage, the shell fabric, zip, thread and lining rows each show a navy reference and a sage reference.
Always use colour references rather than words. "Navy" means different things to different mills. For dyed materials, the colour reference is confirmed through a lab dip, a small dyed swatch the mill sends for approval. Our guide to what a lab dip is explains that process.
Three linked documents. One change moves all three.
A BOM is the list of materials and components, with quantities and costs. A tech pack is the complete package a factory follows: the BOM plus sketches, measurements, construction details, colourways and labelling. See our guide to what a tech pack is. A costing sheet shows the full cost of the product: the material cost from the BOM, plus labour, overheads, duty, freight and margin.
If the BOM changes, the tech pack and the costing sheet must change with it.
For a small range, a spreadsheet BOM works. As styles, colourways and suppliers grow, keeping every BOM in step with its tech pack, costing and purchase orders becomes the main source of errors. A PLM (product lifecycle management) system keeps the BOM on the product record, next to the tech pack, comments and approvals. If you are new to it, read our guide to what PLM is.
How Polluxa helps
Polluxa PLM is product lifecycle management software for fashion, footwear, beauty, consumer goods and manufacturing brands. In our PLM software for fashion and consumer brands, the BOM is part of the product record, not a separate file.
- BOMs no longer drift from the tech pack. With Product Development, tech packs, BOMs (materials lists), comments and approvals live on the product, with every version saved.
- Swapped trims no longer go unnoticed. Every change is recorded with who made it and when.
- Suppliers no longer work from old lists. Tech packs and materials lists are shared with suppliers, and each supplier sees only their part.
- Colourways no longer sit in a side file. Seasons, line plans and colourways sit together, next to the styles they belong to.
- Purchase orders are no longer retyped. With PO Worksheets, create supplier-ready purchase orders from product data.
Start this week
- Open the BOM of your best-selling style and check that every quantity has a unit.
- Compare it line by line with the latest tech pack, and note every difference.
- Add a colour reference for each colourway on every dyed or coloured line.
When you want to see this on your own styles, book a demo.
Frequently asked questions
BOM stands for bill of materials. It is the list of every material and component in a style, such as fabric, trims, labels and packaging, with the supplier, colour, quantity and cost of each.
The BOM is one part of the tech pack. The tech pack is the full instruction set for the factory, including sketches, measurements, construction and labelling. The BOM covers only the materials and components.
Usually the designer, technical designer or product developer, with input from sourcing on suppliers and prices. The factory often adds consumption figures and confirms what it can source.
Fabric consumption is usually worked out from the pattern marker, which shows how pattern pieces fit across the fabric width. Divide the marker length by the number of garments in it, then add a wastage allowance. Your factory can confirm the figure.
Yes, and many brands start there. The problem comes later, when the BOM, tech pack, costing and purchase orders are separate files that must all be updated by hand after every change.
