The formula
This is the standard quick estimate used for knit tops:
Fabric per garment (g) = (body length + sleeve length + length allowance) × (chest width + width allowance) × 2 × GSM ÷ 10,000
All measurements are in centimetres. Chest width is measured flat, from side seam to side seam. The × 2 covers front and back. Wastage is then added as a percentage.
Example with the default values: (72 + 22 + 10) × (54 + 4) × 2 × 180 ÷ 10,000 = 217 g, or 239 g with 10% wastage.
What the estimate leaves out
- Hoods, pockets and wide rib trims. Add these as extra length or a higher wastage figure.
- Marker efficiency. Real consumption depends on how well the pattern pieces nest on your fabric width.
- Shrinkage after washing or dyeing.
Use the result for budgeting and to sense-check a quote. A factory works out the exact figure from the marker. Next, price the fabric with the fabric cost calculator.
Common questions
What wastage percentage should I use?
Around 8 to 12% is a common planning figure for knit tops. Garments with many small panels or large prints waste more.
Does this work for woven garments?
It is designed for knit tops. Woven garments are normally calculated in metres from a marker, because the pieces and fabric widths differ more.