GSM — grams per square meter — is the single most useful number on a fabric spec sheet. It tells you how heavy, warm, and durable a garment will feel before a single sample is cut.
What GSM Actually Measures
GSM measures the weight of one square meter of fabric. A higher GSM generally means a heavier, more substantial garment, but weight alone doesn’t tell the whole story — fiber content and knit structure matter just as much.
Common Fleece Weights and Where They’re Used
- 240–280 GSM: Lightweight fleece, suited to warmer climates or layering pieces
- 300–340 GSM: The standard mid-weight range for everyday hoodies and crewnecks
- 350–400+ GSM: Heavyweight streetwear fleece, prized for structure and a premium hand-feel
- 450 GSM and above: Very heavy, often used for statement outerwear pieces
Fleece Texture: Loopback vs. Brushed
Loopback fleece keeps its looped interior for a more casual, textured feel, while brushed fleece is combed for a softer interior finish. Brands chasing a premium streetwear look often lean toward brushed, heavyweight fleece for that cozy-but-structured feel buyers associate with quality.
When you’re briefing a factory, always specify GSM alongside fiber content and finish — “heavyweight fleece” means something different to every supplier until you put a number on it.