GSM stands for grams per square metre. It tells you how heavy a fabric is: the higher the number, the heavier and usually thicker the fabric. It is one of the first things a factory will ask you, because it affects the feel, the look and the price of every garment.
Typical GSM ranges
These are common ranges, not fixed rules. The right weight depends on your market, your price point and the season.
- Lightweight T-shirts: roughly 120 to 150 GSM
- Regular T-shirts: roughly 160 to 180 GSM
- Heavyweight T-shirts: roughly 200 to 240 GSM
- Polo shirts in pique: roughly 180 to 220 GSM
- Sweatshirts and hoodies: roughly 240 to 400 GSM
What changes with weight
Heavier fabric generally feels more substantial, hangs straighter and is less see-through. It also uses more yarn, so it costs more and weighs more in the carton, which affects freight.
Lighter fabric is cooler to wear and cheaper per piece, but can feel thin if the yarn or knit quality is poor.
GSM is not the same as quality
Two fabrics with the same GSM can feel very different. Yarn type (combed or carded cotton), yarn count, knit structure and finishing all matter. A well-made 160 GSM combed cotton jersey can feel better than a rough 180 GSM fabric.
How to specify it
State the GSM you want with a tolerance, for example 180 GSM plus or minus 5 percent, along with the fibre content and the knit type. Then ask for a fabric swatch or sample garment and check it in your hand before approving bulk production.
