For tubular fabric the flattened width is doubled first, because a flattened tube presents two layers of fabric.
This is a clean-production figure. It excludes yarn consumed knitting fabric that is later downgraded or rejected — a cost that does not appear in any consumption formula but appears in every yarn bill.
Multiply GSM by the fabric area in square metres. Area is width in metres times length in metres. Add a wastage allowance on top — that gives the yarn quantity you actually need to buy.
Typical knitting wastage runs 3–5% for well-controlled operations covering set-up, joins and end-of-roll losses. Add process losses separately: scouring and dyeing shrinkage can remove a further 5–8% of weight.
Yes. Tubular knit width is half the flattened circumference, so the fabric area doubles when opened. Enter the open width if you are calculating against an open-width specification, or set the calculator to tubular and it will double the width for you.
The usual culprits are defect-related. Fabric knitted with a fault still consumed yarn, and rolls downgraded at inspection consumed full yarn for partial value. A 5% downgrade rate is 5% of your yarn purchase converted into seconds quality.
Every metre rejected at the inspection table was knitted with first-quality yarn on paid machine hours. Catching the fault at the machine is the only point where that yarn is still recoverable.
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