What Is 240 GSM Cotton? A Plain-English Guide

If you’ve shopped for a good oversized t-shirt, you’ve seen 240 GSM cotton in the specs — and probably wondered whether it actually matters or it’s just a number brands throw around. It matters. Here’s what GSM means, why 240 sits at the heavier, more premium end, and how to tell the difference with your own hands.

What GSM actually measures

GSM stands for grams per square metre — the weight of the fabric across a fixed area, literally how much a one-metre square of the cloth weighs. Higher GSM means denser, heavier fabric; lower GSM means thinner and lighter. It’s the single most useful number for judging how substantial a t-shirt will feel before you ever touch it.

Where 240 GSM sits

Most mass-market and fast-fashion tees land between 140 and 180 GSM — thin, lightweight cotton that can feel flimsy in hand, sometimes lets light through, and tends to sag or lose shape after a few washes. At 240 GSM you’re in genuine heavyweight territory: thick, opaque cloth that holds structure instead of clinging, and stands up to repeated wear and washing.

• 140–180 GSM — lightweight everyday tees; thin, can be see-through, shorter lifespan.
• 190–220 GSM — mid-weight; a step up, common in better basics.
• 230–260 GSM — heavyweight; structured, opaque and durable, where 240 GSM lives.

Why heavier cotton matters for an oversized fit

Weight and fit are connected. An oversized cut has more fabric hanging off the body, so lightweight cloth collapses and drapes limply — the shape falls flat. Heavyweight 240 GSM cotton has the body to hold a structured drop: the shoulders sit where they’re meant to, the hem falls cleanly, and the silhouette reads intentional rather than baggy. If you’re buying oversized specifically, GSM matters more, not less.

What “bio-washed” and “pre-shrunk” add

Weight isn’t the whole story. Two finishes do the rest of the work:

• Bio-washed — treated with enzymes that lift away loose surface fibres, leaving the fabric softer and less prone to pilling, without thinning it.
• Pre-shrunk — shrunk during manufacturing rather than on your first wash, so the size you buy is the size it stays. This is the finish that quietly prevents a lot of “it fit, then it didn’t” disappointment.

How to judge GSM with your own hands

You won’t always have a spec sheet, so here’s the quick test:

• Hold it up to light. Heavyweight cotton is opaque; thin tees glow through.
• Feel the weight. A 240 GSM tee has real heft — it feels like a garment, not a wrapper.
• Stretch and release. A dense knit springs back; loose, thin knit stays distorted.
• Check the hem and collar. Reinforced stitching and a collar that holds its shape signal a tee built to last.

The short version

240 GSM cotton is heavyweight, opaque, structured and durable — the weight that lets an oversized tee actually look oversized instead of shapeless. Every OverBlaze oversized tee is cut from 240 GSM cotton, bio-washed and pre-shrunk, with high-density prints and reinforced stitching.

Next, work out your size with our Size & Fit Guide, or browse the oversized tees.