Understanding Fabric GSM
The single number that predicts how a garment will hang, wear and price — and the four things GSM will never tell you.
GSM stands for grams per square metre: the weight of one square metre of cloth. It is the most useful single specification in a fabric conversation because it correlates directly with opacity, structure, warmth, cost and the way a garment falls from the shoulder.
It is also routinely misunderstood. GSM measures weight per area, not thickness, not quality, and not fibre. This guide covers how to use it well and where it stops being informative.
How to read GSM in practice
Broadly: below 100 GSM you are in sheers and fine voiles; 100–150 GSM covers shirting, summer dresses and light linings; 150–250 GSM covers most prêt, heavier dresses and light jackets; above 250 GSM you are into trousering, upholstery weight, coats and structured outerwear.
These bands shift by fibre. A 120 GSM silk feels substantial; a 120 GSM cotton feels light; a 120 GSM linen sits somewhere between and behaves quite differently again. Use GSM as a comparison tool within a fabric family, not across all of them.
- Under 100 GSM — organza, voile, chiffon, fine Chanderi
- 100–150 GSM — shirting, summer dresses, linings, light kurtas
- 150–250 GSM — prêt, dresses, light jackets, most everyday cloth
- 250 GSM+ — trousering, structured jackets, coats, heavy brocades
What GSM does not tell you
A heavy cloth is not automatically a good cloth. A dense, low-count fabric can be heavy and coarse; a fine, high-count silk can be light and exceptional. GSM says nothing about yarn quality, twist, fibre length, finish or how the cloth will feel against skin.
It also says nothing about drape direction. Two fabrics at identical GSM can behave completely differently depending on weave and twist — a 150 GSM crepe flows and a 150 GSM taffeta stands. Always handle the swatch; never buy on a number alone.
GSM, width and the cost you actually pay
Fabric is frequently quoted per metre while its weight varies with width. A 58-inch cloth at 200 GSM contains substantially more material per running metre than a 44-inch cloth at the same GSM, and that difference belongs in your costing sheet.
For accurate comparison, convert to weight per running metre: GSM × width in metres. Compare suppliers on that figure alongside price, and the true value picture usually changes.
- Always record GSM together with usable width
- Compare cost against grams per running metre, not per metre alone
- Confirm whether width quoted is cuttable or includes selvedge
Specifying GSM in an order
Never write a single figure. Woven cloth is produced within a range, and a hard number invites either rejection disputes or quiet substitution. Specify a band — 180–200 GSM, for example — with a stated tolerance, and name the test method used.
Then verify on receipt. A GSM cutter and a lab balance take two minutes per lot, and catching a downward drift at goods-in is far cheaper than discovering it in a finished garment run.
- GSM is grams per square metre — weight per area, not thickness or quality.
- Read GSM bands within a fibre family; they do not transfer across fibres.
- Weave and twist govern drape as much as weight does.
- Always pair GSM with usable width when comparing cost.
- Specify a GSM band with tolerance, and verify each lot on arrival.
Bring the question to the studio
Reading only takes you so far. Handle the cloth, compare qualities side by side, and let us build the fabric plan for your collection with you in Ahmedabad.