Fashion BOM: The Complete Guide to the Apparel Bill of Materials
What goes into a garment bill of materials, how colorway BOMs work, and how the BOM drives your costing, your purchase orders and your margin.
Joe Lauder·Founder, Kōbō·Updated Jul 29, 2026What Is a Fashion BOM?
A fashion BOM, or bill of materials, is the complete list of everything that goes into one garment. Fabrics, threads, closures, labels, trims, hardware and packaging, each with a description, a supplier, a unit, a consumption figure and a price. Add the lines up and you have your material cost per unit.
It's the least glamorous document in product development and the one that decides whether you make money. The design sets what the garment is. The BOM sets what it costs, what you order, and whether the factory can start on time. Everything downstream, from the cost sheet to the purchase order to the delivery date on your critical path, is built on it.
If you've heard the term "bill of materials" in an engineering or manufacturing context, the principle is the same. The practice is not. An apparel BOM has to cope with colorways, size-dependent fabric consumption, wastage percentages, MOQs on trims, and suppliers who quote in three different currencies. That's why a generic BOM template rarely survives contact with a real collection.
Why an Apparel BOM Isn't a Generic BOM
Most bill of materials advice online is written for hard goods: a fixed parts list, a fixed quantity, one version of the product. Apparel breaks all three assumptions, and the differences are exactly where BOMs go wrong.
Quantities aren't whole numbers - You don't use one fabric, you use 1.82 meters of it, and that figure comes off the marker rather than out of a catalogue. Trims are counted, fabric is measured, and the two behave differently in costing.
One style is many products - A single style in four colorways is four different material sets. The BOM has to carry the shared structure and the per-colorway differences at the same time.
Consumption moves with size - A size XL takes more shell fabric than a size XS. Whether you cost on a blended average or size by size changes your margin, particularly on outerwear and heavier fabrics.
Wastage is a line item, not an afterthought - Cutting waste, shrinkage and fabric faults all sit between what the pattern needs and what you actually buy. If your BOM only holds net consumption, your purchase orders will be short.
Trims carry MOQs - A custom woven label or a branded puller has a minimum order that has nothing to do with your production quantity. That surplus is real money and it belongs in the plan.
Suppliers are plural - Fabric from one mill, trims from three vendors, packaging from a printer, all with their own lead times and currencies. The BOM is where those relationships get pinned to the product.
What Goes In an Apparel BOM
Almost every garment BOM sorts into seven categories. Working through them in order is the simplest way to stop things being forgotten, because the things that get forgotten are almost always the small ones: the flag label, the spare button, the polybag.
| Category | Common items | Data you need on every line |
|---|---|---|
| Fabrics | Shell fabric, lining, interlining, interfacing, pocketing | Composition, weight (GSM), width, colorway, supplier, article number, price per meter |
| Threads | Topstitch, construction, overlock, buttonhole | Type, color reference, ticket number, supplier, price per cone |
| Closures | Zippers, buttons, snaps, hooks, hook and loop tape | Type, size, color, material, supplier, price per unit |
| Labels | Main label, care label, size label, content label, flag label | Type, size, material, artwork file, supplier, price per unit |
| Trims | Elastic, drawcord, ribbon, binding, piping | Type, width, color, composition, supplier, price per meter |
| Hardware | Grommets, rivets, D-rings, buckles, adjusters | Type, size, finish, material, supplier, price per unit |
| Packaging | Hangtag, price ticket, polybag, tissue, carton | Type, size, artwork, supplier, price per unit |
The right-hand column is the part people skip. A BOM line that reads "black zip" is a note to yourself, not a purchasing instruction. A line that reads "YKK #5 Vislon open-end, 62cm, black, art. VS5-OE, $0.84" is something a factory can order and an accountant can check.
A Worked Example
Here's a stripped-back BOM for a simple cotton shirt. A real one carries more detail, colorway rows and wastage, but the shape is the same: one line per component, consumption times price, totalled at the bottom.
| Component | Description | Supplier | Unit | Qty | Price | Total |
|---|---|---|---|---|---|---|
| Shell fabric | 100% cotton oxford, 140gsm, white | Fabric Co. | meter | 1.8 | $6.50 | $11.70 |
| Interlining | Fusible collar and cuff interlining | Trim World | meter | 0.3 | $2.00 | $0.60 |
| Buttons | 14L mother of pearl, 4-hole | Button Ltd | piece | 9 | $0.25 | $2.25 |
| Thread | Poly-cotton 40/2, white | Thread Co. | cone | 0.02 | $3.00 | $0.06 |
| Main label | Woven damask, 30x60mm | Label Pro | piece | 1 | $0.15 | $0.15 |
| Care label | Printed satin, content and care | Label Pro | piece | 1 | $0.08 | $0.08 |
| Hangtag | Brand hangtag with string | Print Co. | piece | 1 | $0.20 | $0.20 |
| Polybag | Clear PE bag, 30x40cm | Pack Ltd | piece | 1 | $0.05 | $0.05 |
Material cost: $15.09 per unit, before wastage, labour, freight and duty.
Note what this figure isn't. It's the material cost, not the landed cost and not the FOB price. Adding labour, wastage, freight and duty is a separate exercise, and our garment costing guide walks through it. If you want to run the numbers now, the free garment costing calculator takes a material total like this one and builds the full cost sheet around it.
Colorway-Level BOMs
This is the part of BOM work that's specific to fashion, and the part spreadsheets handle worst. The moment a style goes into more than one colorway, some of your components move and some of them don't.
The shell fabric changes. The thread changes with it. The zipper tape, the binding, the drawcord and often the label change too. The interlining, the buttons on a natural-horn style, the hangtag and the polybag usually don't. Prices can move as well, because a piece-dyed navy and a specially matched brand color rarely cost the same.
The approach that holds up is a two-layer BOM: a style-level list of every component and its consumption, with colorway rows underneath for anything that varies. You maintain the structure once. You cost each colorway accurately. And when the mill raises the price on one color, you correct one row rather than reopening four files.
Styles with sub-assemblies, like a lined jacket where the body, the lining pack and the hood each carry their own components, go a level deeper again. That's a multi-level BOM, and it's covered in detail in our guide to multi-level bill of materials hierarchy.
Consumption, Wastage and Yield
Consumption is where BOM accuracy is won or lost. Everything else on the line is a fact you can look up. Consumption is a number you have to derive, and getting it from the wrong place is the most common cause of a BOM that costs beautifully and orders badly.
Take fabric consumption from the marker - Not from an estimate, and not from a similar style last season. The marker tells you what the pattern actually needs at your size ratio and fabric width.
Hold net and gross separately - Net is what the garment uses. Gross is what you buy after cutting waste, shrinkage and an allowance for faults. Costing runs on gross, and if your BOM only stores net, you'll under-order every time.
Watch fabric width - A price per meter means nothing without the width it was quoted at. The same fabric at 150cm and 110cm gives you very different consumption for the same pattern.
Count trims honestly - Nine buttons on the placket plus one spare on the care label is ten, not nine. Small under-counts multiply across an order.
Record the unit you bought in - Thread bought by the cone and consumed by the meter needs a conversion factor stored somewhere other than someone's head.
From BOM to Costing
The BOM is the input to the cost sheet. Material cost from the BOM, plus labour, plus wastage, plus freight, duty and any value-added services, gives you a landed cost, and your wholesale and retail prices come off that. Which means a BOM error doesn't stay a BOM error. It becomes a pricing error, and you usually find out after the season is bought.
Our own fashion tech stack research found this is one of the recurring symptoms of a disconnected toolset: final garment costs coming in 15 to 30 percent above estimate, because the BOM was built on component pricing that had gone stale and nobody had updated the exchange rate. The materials didn't change. The record of them did.
A BOM that isn't priced today isn't a BOM. It's a memory of what things used to cost.
The fix is structural rather than diligent. When component prices live in one shared library and every BOM references that library, updating a price updates every style that uses it. That's the single biggest reason brands move BOM work out of spreadsheets, and it's how Kōbō's bill of materials module is built: component libraries, supplier pricing in multiple currencies, and cost rollups that recalculate when the underlying price moves.
BOM vs Tech Pack
These two documents get conflated constantly, usually because in a good system they arrive together. They answer different questions and they're read by different people.
| Aspect | Bill of materials | Tech pack |
|---|---|---|
| Purpose | Lists every material, quantity and cost | Communicates design, fit and construction |
| Primary user | Costing, sourcing and purchasing | Factory, pattern maker, sample room |
| Key data | Materials, consumption, suppliers, prices | Specs, measurements, construction callouts |
| What triggers a change | New pricing, a supplier swap, a colorway | A design change or a fit correction |
| What it feeds | The cost sheet and the purchase order | Sampling and production instructions |
In practice the BOM is a section of the tech pack, which is why keeping them in separate files causes so much trouble. Change a zipper in the BOM, forget to reissue the tech pack, and the factory sews the old one. If you're building tech packs from scratch, start with our tech pack guide or the free tech pack template, both of which include the BOM section.
Common BOM Mistakes
None of these are exotic. They're the six that show up on nearly every brand's first proper BOM audit, and each one has a cheap fix if you build the check into your process rather than relying on someone noticing.
Missing components
Costs land higher than quoted, and something gets air freighted at the last minute
Fix: Work from a category checklist on every style so nothing gets forgotten
Wrong consumption
Over-ordering ties up cash in fabric you can't use; under-ordering stops the line
Fix: Take consumption from the actual marker, then add your agreed wastage percentage
Stale pricing
Margin quietly disappears between the range plan and the purchase order
Fix: Re-confirm component prices with suppliers before you sign off costing
No supplier reference
You can't reorder, and the knowledge sits with one person
Fix: Always record supplier name, contact and article number against the component
No version control
The factory orders from a BOM you replaced three weeks ago
Fix: Date every version, or use a system that tracks changes for you
Mixed units
Meters against yards, pieces against dozens, and the maths is wrong everywhere
Fix: Standardise units across all BOMs and document your conversion factors
BOM Best Practices
Adopt these and your BOMs stay useful as the collection grows rather than becoming an archive nobody trusts.
Managing BOMs at Scale
Spreadsheet BOMs work fine at ten styles. They stop working somewhere around fifty styles with multiple colorways each, and the failure isn't dramatic. It's slow: a price update that takes a day, a component that exists under four slightly different names, a purchase order raised from a file that turned out not to be the latest one.
What changes when BOMs move into a PLM is mostly about the data model rather than the features list:
Shared component libraries - Enter a fabric once with its composition, width, supplier and price, then reference it from every style that uses it.
Pricing that rolls through - Update a component price in the library and every BOM referencing it recalculates, so costing reflects what things cost today.
Colorway inheritance - Build the style BOM once and generate colorways that inherit the shared components, overriding only what actually changes.
Supplier collaboration in place - Suppliers quote against the component rather than in an email thread, so the price and the material stay attached to each other.
Version history - See what changed, when, and which BOM version a given production run was ordered against.
Bulk changes - Swap a discontinued trim across every style that uses it in one action instead of opening fifty files.
If you're weighing that move up, our comparison of the best fashion PLM software covers the realistic options at each brand size. Kōbō sits at $140 to $300 per user per month with supplier seats included at no cost, and most teams are live in one to two weeks. Full detail is on the pricing page.
Frequently Asked Questions
What is a BOM in fashion?
A BOM in fashion is the complete list of materials needed to make one garment: fabrics, threads, closures, labels, trims, hardware and packaging, with the consumption, supplier and price for each line. It's the document that turns a design into something you can cost and buy. Where a generic manufacturing BOM lists parts, a fashion BOM has to handle colorways, size-dependent consumption and fabric wastage.
What is included in an apparel BOM?
An apparel BOM covers seven groups of components: fabrics (shell, lining, interlining, pocketing), threads, closures such as zippers and buttons, labels, trims such as elastic and drawcord, hardware, and packaging including hangtags and polybags. Each line needs a description, a supplier and article number, a unit, a consumption figure and a price, so the BOM totals to a material cost per unit.
What's the difference between a BOM and a tech pack?
The BOM lists what the garment is made from and what it costs. The tech pack explains how it's built: specs, measurements, construction callouts and artwork placement. The BOM is read by sourcing and purchasing, the tech pack by the pattern maker and the sample room. In most PLM systems the BOM sits inside the tech pack, so a material change updates both at once.
Do you need a separate BOM for each colorway?
You need a colorway-level BOM whenever a component changes with the color, which in practice is most styles. The shell fabric, the thread, the zipper tape and often the label all move with the colorway, and their prices can differ too. The workable approach is one style BOM that holds the shared structure, with colorway rows underneath for anything that varies, so you cost each colorway accurately without rebuilding the whole list.
Can you manage fashion BOMs in a spreadsheet?
For a first collection of ten or fifteen styles, yes. The failure point is repetition: the same fabric appears in thirty styles, a supplier raises the price, and you now have thirty files to correct by hand. Once you're running multiple colorways per style across several suppliers, a PLM with a shared component library keeps the pricing in one place and rolls the change through every BOM that uses it.
Joe's the founder of Kōbō Labs. Before this, he founded Satta, a fashion brand he scaled to sell internationally at Mr Porter, SSENSE, and Beams Japan. A decade of running his own brand - design, suppliers, production, the lot - is what Kōbō is built on.
Related Articles
Build BOMs your factory can actually order from
Kōbō gives you a shared material library, colorway BOMs, and costing that updates itself. Supplier seats are free, and most teams are live in one to two weeks.
Start Free Trial