GSM, Width and Yield: How to Read a Knitted Fabric Specification
Short answer: GSM is the weight in grams per square metre, width is the cuttable width in centimetres, and yield is the number of metres you get from one kilogram. Together they decide both how a fabric handles and what it costs per garment: metres per kg = 1000 ÷ (GSM × width in metres).
A specification sheet is a promise about three things: how heavy the cloth is, how wide the usable cloth is, and how much of it you receive for a given weight. Buyers who read those three numbers together rarely get surprised by a roll. Buyers who read only GSM often do.
What GSM tells you — and what it does not
GSM (grams per square metre) is a weight, not a thickness and not a measure of quality. A 300 GSM fleece and a 300 GSM dense interlock can feel nothing alike, because loft, yarn count and finishing change the volume without changing the weight. GSM is useful for comparing fabrics within the same construction, and for calculating yield. It is not a substitute for a swatch.
Our own knitted range runs from 120 GSM to 320 GSM. Prices on each product page are quoted in USD per kilogram in two tiers (standard and volume orders), with composition, GSM and cuttable width listed together.
| GSM band | Typical character | Examples in our range |
|---|---|---|
| 120–160 | Light base layers, linings, summer jerseys | Cotton Base-Layer Jersey 120, Butterfly Mesh 160 |
| 160–200 | Everyday tees, sportswear, prints | Sorona Single Jersey 165, Stretch Bird-Eye 180 |
| 200–260 | Structured double knits, heavier jerseys | Acetate-Touch Double-Face 220, TR Eyelet Jacquard 250 |
| 260–320 | Fleece, brushed warmth, outer layers | Single-Sided Plush Fleece 300, Double-Sided Cationic Warm Fleece 320 |
Width: use the cuttable number, not the loom width
Width is the usable, cuttable width after the fabric is relaxed and finished. Selvedge, needle lines and finishing shrinkage are not part of it. Our knitted qualities run from 140 cm to 300 cm; the widest is a 300 cm circular-knit rib intended for trim, and the narrowest are woven and double-face constructions around 140–162 cm. If a marker is planned on the nominal width rather than the cuttable width, the shortfall shows up at the cutting table.
Yield: the formula worth keeping on your desk
One metre of fabric at width W metres has an area of W m². At GSM G, it weighs G × W grams, or G × W / 1000 kg. So:
metres per kg = 1000 ÷ (G × W) and kg per metre = G × W ÷ 1000
Worked example. A 240 GSM brushed milk silk at 160 cm: W = 1.60 m, so one metre weighs 240 × 1.60 / 1000 = 0.384 kg, and one kilogram gives 1000 / (240 × 1.60) = 2.60 metres. A 320 GSM fleece at 175 cm gives only 1.79 m/kg. Same weight of roll goods, very different garment count.
Why two 180 GSM fabrics behave differently
Construction is the missing variable. A single jersey, a 2×2 rib, a piqué and a brushed fleece can all be produced at similar GSM, but loop geometry, elastane content and brushing change stretch, recovery, drape and perceived warmth. Yarn also matters: cationic polyester, Sorona, modal, Tencel Lyocell and cotton each bring a different hand at the same weight. When a spec sheet feels surprising, ask for the construction and the composition, not just the GSM.
Frequently asked questions
What GSM is right for a T-shirt?
For a standard single-jersey tee, 150–180 GSM is the usual working range; 120–140 GSM reads as lightweight and can be sheer in pale colours, while 200 GSM and above moves into structured, heavier tees. Always confirm against a swatch in your actual colourway.
Does the stated width include the selvedge?
No. The width we quote is cuttable width after finishing. Selvedge and needle-line areas are excluded, because they cannot be used in a marker.
How much GSM tolerance should a contract allow?
Knitted fabric is a textile, not a machined part. Agree a tolerance in writing before production — commonly ±5% on GSM and a small allowance on width — and specify whether the price is settled on nominal or actual weight.
Why do we quote per kilogram instead of per metre?
Per kilogram is stable across different widths and is how the yarn and dyeing costs are actually incurred. If your costing sheet works in metres, use the conversion in our price per kg to per metre guide.
Need a spec sheet checked before you commit to a marker? Send us the construction, GSM and width and we will confirm yield and composition in writing. You can also browse all 53 fabric qualities.