Guide2 min read

The bill of materials

The bill of materials (BOM) lists everything a garment is made of, one line per material, with enough detail for a factory to source each one, cost the garment and check what arrives.

Updated 30 October 2026

What each line needs

FieldTypical entryWhy it matters
ComponentBody; RibWhere the material goes, so it can be costed and checked
MaterialBrushed-back fleeceThe construction: which knit or weave
Content80% cotton, 20% polyesterFibre by weight, adding to 100%; it goes on the care label
Weight340 g/m²Decides the handle, the cost and how the garment hangs
Colour18-0601 TCXOne per colourway, as a TCX code or a lab dip
PlacementBody, sleeves, hood and pocketWhich pieces are cut from it
Supplier and referenceNominated, or factory to sourceWho buys it, and to what standard
The fields of a BOM line
CodeComponentMaterialContentColour
ABodyBrushed-back fleece, 340 gsm80% cotton, 20% polyester18-0601 TCX Charcoal Gray
BRib2x2 rib, 320 gsm95% cotton, 5% elastane18-0601 TCX Charcoal Gray
  • 01Round cotton drawcord, metal tipsdrawstring · 8 mm · Hood×1
  • 02Metal eyeletsother · 10 mm · Hood front, either side of centre front×2
  • 03Polyester core-spun sewing threadthread · Tex 27 · All seams
The hoodie sample's bill of materials and trims as the Studio exports them. The letters are the codes the PDF uses for each line, and a callout on the flat uses the same letter.

Fabrics

Name the construction a mill would recognise: single jersey, 1x1 rib, brushed-back fleece, cotton twill, oxford. Give the weight in grams per square metre (GSM). Denim is often quoted in ounces per square yard, where 12 oz is about 407 g/m². The fibre content must add to 100%.

If the fabric is washed or dyed as a garment, say so on its line: it changes the shrinkage the pattern must allow for.

Trims

Trims are everything that is not the main fabric. Each one needs its size, its quantity per garment and where it goes.

  • Buttons by ligne: 1 ligne is 1/40 in (0.635 mm), so an 18L button is about 11.4 mm across.
  • Zips by type (coil, metal or moulded), gauge and length, and whether they open at the bottom.
  • Thread by type and weight, with the stitches per inch for each kind of seam.
  • Elastic and drawcord by width or diameter, with the finished length and how the ends are finished.

Colour per colourway

Each line has a colour in every colourway. A TCX code gives the mill a physical standard to match. The Studio matches every colour to its nearest TCX within a ΔE of 4, and marks anything further away for a lab dip.

Nominated or factory-sourced

Say who buys each material. A nominated line names the supplier and the article; a factory-sourced line gives the standard the factory must meet. A line with neither is a common reason a first sample arrives in the wrong fabric.

Labels and packaging belong in it too

Main, care and size labels, hangtags, polybags and cartons are materials as well. List them with their size and placement, and give the care label's content: what it must show depends on the market you sell in.

Make your next pack in the Studio