Fabric is usually the largest cost in a garment, often more than half of the FOB price. Consumption calculation decides how much fabric to book, and therefore both the cost and the risk of a shortage or excess. There are two basic approaches, one for knits and one for wovens.
Knit garments: consumption by weight#
Knit fabric is bought and sold by weight, so consumption is expressed in kilograms per dozen (kg/dz). The method adds up the areas of all panels, converts area to weight using GSM, and adds allowances.
The factor 10⁷ converts cm² to m² (10⁴) and grams to kilograms (10³).
Body block method for T-shirts#
For basic T-shirts, a common quick method treats the body and sleeves as rectangles:
Example: body length 70 cm, sleeve length 20 cm, half chest 52 cm, length allowance 8 cm, width allowance 4 cm, GSM 160.
- Length = 70 + 20 + 8 = 98 cm; width = 52 + 4 = 56 cm
- Net = 98 × 56 × 2 × 160 × 12 / 10⁷ = 2.107 kg/dz
- With 10% wastage: 2.107 × 1.10 = 2.318 kg/dz (about 193 g per piece)
See T-shirt fabric consumption for the details and variations.
Panel method for other knits#
For polos, hoodies, joggers and other knit garments, list each panel with its length and width (including seam allowances), multiply by the number of pieces per garment, and add them up. Separate panels by fabric: body fabric, rib and contrast parts each have their own GSM and price. See knit fabric consumption.
Tubular fabric#
For tubular knits, the tube width matters as well as the weight. If the panel width does not fit the tube, you will waste fabric or need open-width fabric. Check the available diameters with the knitter.
Woven garments: consumption by length#
Woven fabric is bought by meters or yards. The most accurate consumption comes from the marker: the layout of all pattern pieces on the fabric width.
Example: a shirt marker is 6.20 m long with 4 garments. The factory adds 3% for end loss.
- 6.20 / 4 = 1.55 m
- 1.55 × 1.03 = 1.597 m per shirt (19.16 m per dozen)
Before a marker exists, merchandisers estimate from a previous similar style or from a simple area method, then confirm with the CAD marker. See marker making.
Allowances#
| Allowance | What it covers |
|---|---|
| Marker waste | Fabric between pattern pieces; reflected in marker efficiency |
| End loss | Fabric at each end of the lay |
| Splicing and defects | Fabric removed for faults |
| Shrinkage | If the fabric shrinks in processing after cutting (washed garments) |
| Cutting and sewing rejects | Replacement panels |
| Shade and roll ends | Short ends that cannot be used |
Use allowances based on your factory's records for similar styles and fabrics. A single fixed percentage for every style usually either over-books or under-books.
Common mistakes#
- Using full chest instead of half chest in the T-shirt formula, which doubles the fabric.
- Using gross fabric width when the cuttable width inside the selvedges is narrower.
- Ignoring size ratio: a consumption for size M does not represent an order with many XL and XXL.
- Forgetting rib and trims made of fabric, such as neck tape, pocket bags and facings.
- Using greige GSM instead of finished GSM.
- Mixing units: inches, centimeters, yards and meters in one calculation.
Tools#
- T-shirt consumption calculator
- Knit fabric consumption calculator for panel-by-panel knits
- Hoodie consumption calculator
- Woven fabric consumption calculator
- Marker efficiency calculator
To cut waste once consumption is set, see reducing fabric waste in cutting.
Related guides#
- Garment costing: where the consumption figure ends up in the garment price.
- Knit vs woven fabric: why knits are booked by weight and wovens by length.