Quick answer: GSM stands for Grams per Square Metre — the industry measure of how heavy, thick and durable a t-shirt fabric is. Lightweight sits around 120–150 GSM, midweight (the most versatile, everyday range) is 150–180 GSM, and heavyweight, structured tees run 180–260 GSM. There's no single "best" GSM — the right number depends on the season, the fit, and how you want the t-shirt to feel.
Everything you need to know before buying an oversized tee — GSM explained, fit types, fabric quality, stitching, and how to spot a t-shirt that's actually built to last.
