What is GSM in fabric? A weight guide for apparel designers
GSM means grams per square meter — the weight of one square meter of fabric. It is the first number on most mill spec sheets and the quickest way to tell a sheer blouse fabric from a hoodie fleece. But weight is only a starting filter: it says nothing about fiber, drape or the exact color.
Fabric GSM chart for apparel
Typical ranges used in apparel sampling. Mills, fibers and constructions vary, so treat these as a guide, not a spec.
| Weight | Feel | Common apparel uses |
|---|---|---|
| Under 100 gsm | Very light, often sheer | Chiffon, georgette, voile, linings, summer blouses |
| 100–150 gsm | Light | Poplin and lawn shirting, light linen, light jersey |
| 150–200 gsm | Light to medium | T-shirt jersey, viscose and lyocell dresses, linen shirts |
| 200–250 gsm | Medium | Heavyweight tees, piqué polos, twill trousers |
| 250–300 gsm | Medium to heavy | French terry, sweatshirts, chinos, light denim |
| 300+ gsm | Heavy | Fleece hoodies, heavier denim, coating, canvas outerwear |
What GSM does not tell you
- Fiber. A 180 gsm linen and a 180 gsm cotton jersey feel nothing alike.
- Construction. Knits and wovens at the same weight differ in stretch, drape and recovery.
- Opacity and hand. Finishing, yarn count and density change how sheer or soft a fabric is.
- Quality. Heavier is not better. Choose the weight that fits the garment.
- Color. Mills update their colors often, and photos show structure and texture, not every available shade. Confirm color with the physical card.
Convert oz/yd² to GSM
Denim and some US spec sheets quote ounces per square yard. 1 oz/yd² ≈ 33.9 gsm. So 10 oz denim is roughly 339 gsm and 12 oz is roughly 407 gsm. To go back, divide GSM by 33.9.
To check a sample yourself, cut a 10 × 10 cm square (100 cm²), weigh it in grams and multiply by 100. A round GSM cutter does the same job more precisely.
Shortlist by GSM, then confirm by touch
- Filter the catalog by weight. Start with light fabrics under 150 gsm, 150–250 gsm or 250 gsm and up. Or describe the garment in AI fabric search.
- Request the physical cards. Add up to 10 fabrics to a Swatch Box. The cards are free; the fee covers coordination and worldwide express shipping — $69 for up to 5 swatches or $119 for up to 10.
- Test the one you lock. Upgrade to a 1–10 m cut sample for wash and drape tests: $4 per fabric plus shipping at cost.
FAQ
What is GSM in fabric?
GSM means grams per square meter: the weight of one square meter of fabric. A higher number means a heavier fabric for the same area. GSM alone does not tell you the fiber, construction, drape or color.
What GSM is good for a T-shirt?
Many T-shirt jerseys fall roughly between 140 and 200 gsm, and heavyweight tees often go above 200 gsm. Ranges vary by mill, fiber and knit, so confirm the weight and hand with a physical swatch.
Is a higher GSM fabric better quality?
Not necessarily. Higher GSM means heavier, not better. A light lyocell or silk can be the right premium choice for a blouse, while a 300 gsm fabric would be far too heavy. Choose GSM by end use.
How do I convert oz/yd² to GSM?
Multiply ounces per square yard by about 33.9. For example, 10 oz/yd² denim is roughly 339 gsm. To convert back, divide GSM by 33.9.
Can I filter SwatchFree fabrics by GSM and check them in person?
Yes. The fabric catalog has a GSM filter. Shortlist fabrics, then request physical mill color cards in a Swatch Box: the cards are free; the fee covers coordination and worldwide express shipping — $69 for up to 5 swatches or $119 for up to 10, with a maximum of 10 fabrics per box. For wash or drape tests, order a 1–10 m cut sample at $4 per fabric plus shipping at cost.
Fabrics by weight in the catalog
Acetate silk crepe de chine60 gsm · very lightBamboo cotton single jersey145 gsm · tee weight
Brushed cotton canvas270 gsm · medium-heavyPima cotton brushed fleece480 gsm · heavyPhotos show structure and texture; confirm current colors with the physical card.