"Garment Bill of Materials (BOM): How to Build a BOM Your Factory Can Quote From"

A garment bill of materials (BOM) is the section of a tech pack that lists every physical component required to make a style. It is where “black zipper” becomes a specific zipper type, length, colour and supplier reference—and where a factory gets enough information to quote without making expensive assumptions.

For a simple T-shirt, the BOM may be short. For a jacket, bag or multi-colour activewear style, it can become the document that keeps fabric, trims, labels and packaging aligned from first sample to bulk production.

What is a garment BOM?

A garment BOM is a structured list of materials, components and production inputs for one style. It normally includes:

• Main and secondary fabrics
• Lining, interfacing and pocketing
• Thread, elastic, bindings and tapes
• Zippers, buttons, snaps and other hardware
• Woven labels, care labels, hangtags and packaging
• Colour references, placement and supplier details

The BOM does not replace construction notes or a measurement spec sheet. It connects them. The construction page says how a pocket is sewn; the BOM identifies the pocketing fabric, zipper and label that must be used.

Why factories need a complete BOM before quoting

When a factory receives a sketch without a detailed BOM, it must fill the gaps. It may assume a lower-cost zipper, a different fabric weight, an available lining or a generic label. The quote can look attractive, but it may no longer represent the garment you intended to make.

A usable BOM helps a factory:

1. Calculate material consumption and cost accurately.
2. Identify which items it can source locally and which need a nominated supplier.
3. Flag unavailable components before sampling begins.
4. Build the same material plan into every sample and production order.
5. Prevent unapproved substitutions.

The columns every clothing BOM should include

Use one row per material or component. The exact layout can vary, but these fields make the document practical.

Example: overshirt BOM

Separate “known” from “TBC” materials

Do not leave a BOM cell blank. A blank may look like an omission; TBC tells the factory that the decision is open and needs to be priced or sampled.

For a component that is still under review, write a clear action:

• TBC — factory to propose 3 recycled zipper options
• TBC — submit two lining qualities at target price
• Approved only after brand signs off on lab dip

This protects the production timeline while making ownership visible.

Add supplier references and substitution rules

Supplier information is especially important for fabrics, hardware, labels and branded packaging. If you have a preferred supplier, include the supplier name, item code and minimum order quantity when relevant.

If a factory may source an alternative, define the condition rather than using vague wording. For example:

Factory may propose an equivalent option only if fibre content, weight, colour and hand feel are approved in writing before sample cutting.

For branded components, use a firmer rule:

Do not substitute without written approval from the brand.

That sentence is simple, but it prevents an operational decision from becoming an assumption.

Match the BOM to the rest of the tech pack

Before sending a tech pack, compare the BOM against the technical flat, colourway page and construction notes.

• Every visible trim in the flat sketch should have a BOM row.
• Every material named in construction notes should have a specification.
• Every colourway should identify whether trims change with the body colour.
• Artwork, care labels and hangtags should point to their approved files.

If the jacket has two chest pockets in the sketch but the BOM includes only one pocket zipper, the factory should not be asked to resolve that conflict.

Use BOM versions during sampling

Treat the BOM as a controlled production document, not a one-time list. When a material changes, update the version number and revision history alongside the rest of the tech pack.

For example:

• v1.0 — initial quote BOM
• v1.1 — main fabric colour corrected
• v1.2 — approved zipper reference added
• v2.0 — lining changed after fit sample

Send the updated file with a short instruction: “Please replace the previous BOM and confirm receipt.” This is particularly useful when a factory team has separate merchandising, sampling and purchasing contacts.

Build your garment BOM in ThreadPack

ThreadPack keeps BOM rows beside technical flats, measurement specs, construction notes and revision history, so the factory is not working from scattered spreadsheets and attachments. Start each style with the components you know, mark unresolved decisions as TBC and turn approvals into a clean, factory-ready record.
FAQ

Is a BOM the same as a tech pack?

No. A BOM is one section of a full tech pack. The full pack also includes flats, construction details, measurements, colourways, artwork placement and revision history.

Should I include cost in a garment BOM?

Usually, keep supplier prices and target FOB cost in a separate commercial document. The BOM should focus on specifications and approvals so it can be safely shared with production teams.

Can a factory make its own BOM?

It can propose one, but the brand should approve the final BOM. Otherwise the factory may select materials that meet its own availability or cost goals rather than your design and quality requirements.