What Is GSM in Fabric?

GSM is grams per square metre, the weight of a fabric, and for a clothing brand it sets three things at once: how the garment drapes, what it costs and what it costs to ship. A higher number usually means a heavier, thicker and more premium-feeling cloth, and it is the single most useful figure for describing a garment to a manufacturer. Fabric is bought by weight, so moving a tee from 160 to 190 GSM raises the fabric cost of every unit and the freight weight of every carton. On a full container that is a real number, not a rounding error, so settle the weight before you compare quotes. Weight also sets the drape: a lighter cloth drapes, a heavier one gives the garment structure. What the number cannot tell you is how the cloth feels, because yarn, construction and finishing change that at the same weight.

A t-shirt is usually 140 to 180 GSM and a standard hoodie or sweatshirt 280 to 350 GSM, with a lighter and a heavier band on either side of each. The full weight chart runs like this. At 110 to 140 GSM you get lightweight, drapey tees and summer styles. 140 to 180 GSM is the standard everyday t-shirt. 180 to 220 GSM makes a heavyweight, premium tee with structure. 220 to 280 GSM covers heavy tees to about 240 GSM, then lightweight sweats and mid-weight layers. 280 to 350 GSM is the standard hoodie and sweatshirt, and 350 to 500 GSM is for heavyweight, structured streetwear hoodies. Heavier is not always better, so match the weight to the garment and the season you sell into. Each step up the chart adds fabric cost and freight weight to every unit, so choose the lightest band that gives the feel you want, not the heaviest one the budget allows.

No single fabric is best: the right one depends on the garment and the season. For tees and everyday basics, combed cotton single jersey at 140 to 240 GSM is the soft, smooth default, and organic cotton jersey gives the same garments with documentation to stand behind, made in our GOTS-certified facility (RSC 9687). For hoodies and sweats, French terry runs from 240 GSM for lighter, transitional pieces to 500 for heavyweight streetwear, while brushed fleece at 280 to 500 GSM is warmer and cosier. Pique at 190 to 220 GSM is the polo knit, and rib at 280 to 400 GSM does cuffs, collars, waistbands and fitted tops. Modal and bamboo viscose at 140 to 200 GSM are extra-soft, drapey and breathable for loungewear and intimates. Poly/spandex performance blends at 180 to 280 GSM bring stretch, moisture-wicking and recovery to activewear and leggings. Recycled blends, performance or cotton-rich fabrics with recycled content, are lower-footprint versions of the fabrics above.

Two fabrics at the same GSM feel different because GSM only measures weight; the yarn, the construction and the finishing decide the hand. Start with the yarn. Combed ring-spun and open-end cotton can be knitted to the same weight, yet a 180 GSM tee in each feels like a different price bracket, so ask which yarn you are being quoted; a vague answer usually means open-end. Next comes construction. Single jersey, terry, fleece, pique and rib behave differently at identical weight: terry has loops on the back, fleece is terry with those loops brushed into a nap, and rib recovers where jersey relaxes. Then the finishing. Compacting relaxes the knit and takes most of the shrinkage out before cutting; skipping it is a common cost saving and the usual reason a cheap tee loses most of a size in its first wash. Ask for the measurement to be checked after wash testing rather than before.

Give the manufacturer a feel, a number and a reference garment. Decide the feel first, such as a lightweight summer tee or a heavyweight hoodie, then pick the GSM from the weight chart. Name the construction as well as the weight, for example combed cotton single jersey or brushed fleece, because constructions behave differently at the same GSM. Add the yarn and the finish you expect, so every quote prices the same cloth. Then send a garment whose feel you like: we ask for a reference garment alongside a GSM figure because the number alone is not a complete specification. If sustainability matters, ask for certified organic cotton: ours is made in our GOTS-certified facility (RSC 9687), and the scope certificate is available on request. Still unsure? Ask for fabric swatches and a sample, because feeling the cloth beats guessing. Our minimum is 150 pieces per style and per colour.

Yes. Every cotton fabric in our library can be made in organic cotton: single jersey for tees, French terry and brushed fleece for hoodies, sweatshirts and joggers, interlock, rib for cuffs and neckbands, and piqué for polos. The garments are made in our GOTS-certified facility, certificate RSC 9687, and the scope certificate is available on request. The minimum is the same as for conventional cotton, 150 pieces per style and per colour, although certified yarn is bought in its own lots, so tell us early if a colour or weight is unusual. One point about wording: an organic product can only be labelled as GOTS certified when it is made and certified under that standard, so agree the label and hang-tag text with us before printing. If you want an organic range, say so in your enquiry and we quote the organic fabric directly rather than as a later swap.

Each common knit fabric has a weak point worth checking on the sample, before bulk production. Combed cotton single jersey shrinks if it has not been compacted, so ask for the finish. Organic cotton jersey needs the same finishing check, and its certified yarn carries its own lot minimums, though we run it from the same 150-piece minimum as conventional jersey. French terry has loops on the back that can snag on rough trims. Brushed fleece pills sooner when the base yarn is poor. Pique needs interlining in the collar or the collar curls. Rib for cuffs and waistbands needs elastane to recover after wear. Modal and bamboo viscose are weaker when wet, so write the care instructions carefully. Poly/spandex performance fabric needs an opacity check, so always squat-test leggings before bulk. And if a blend is sold as recycled, ask for the GRS or RCS certificate behind that claim.

GSM is measured by cutting a disc of known area from the fabric, usually 100 square centimetres with a round GSM cutter, weighing it and multiplying the grams by 100. Several discs are cut across the width and along the roll and averaged, because weight varies slightly across a fabric. Labs follow published methods: ASTM D3776 covers mass per unit area for most fabrics, and EN 12127 is a small-sample method for woven and knitted fabrics. ISO 3801 is often quoted as well, but it is written for woven fabrics, so a report on jersey, terry or fleece usually cites one of the other two. Samples are conditioned first in the standard atmosphere set out in ISO 139, since damp fabric weighs more than dry. The figure that belongs on your spec is the finished weight after dyeing and compacting, agreed with a tolerance and checked on the pre-production sample.

No. GSM is weight per area, and thickness and yarn count are separate measurements that GSM does not capture. Thickness is how far a fabric measures from face to back. Two fabrics at the same GSM can differ in thickness: a brushed fleece has a raised, airy nap and feels thicker than a tightly knitted interlock of the same weight. Yarn count describes how fine each yarn is. A fine yarn knitted densely and a coarser yarn knitted more openly can reach the same GSM, yet feel and drape quite differently. Thread count, which you may know from bed sheets, applies to woven fabrics and is rarely used for knits. So GSM tells you how much fabric is in a garment, which drives its cost, warmth and freight weight, but not how it will feel. Give a manufacturer the GSM, the construction and the yarn, and send a reference garment whose feel you like.