Weight is the first spec buyers ask for and the one most often misread.
GSM is grams per square metre. Cut a 10 × 10 cm square, weigh it, multiply by 100, and you have the fabric's weight. It tells you how much fibre is in the fabric, which drives cost and, roughly, warmth and opacity.
- 120–150: g/m², shirting and summer tees
- 160–200: g/m², core T-shirts
- 280–350: g/m², sweatshirt fleece
What GSM doesn't tell you
Two 180 g/m² jerseys can feel completely different. Yarn count, twist, knit density and finishing all change the hand without changing the weight much. A compact-spun yarn feels smoother than an open-end yarn at the same weight.
Denim speaks in ounces
Denim is weighed in ounces per square yard. One oz/yd² is about 33.9 g/m², so an 11 oz denim is roughly 373 g/m² and a 14 oz denim roughly 475 g/m².
