What Is GSM in T-Shirts? A Plain Guide to Fabric Weight

Brands print the GSM number on product pages because shoppers now look for it. Google searches in India for "240 gsm" grew about 150 times in five years. Out of the brands in the Desi Drip directory, 81 mention 240 GSM on their websites. This guide tells you what the number means and how to use it when you buy.

#What GSM means

GSM is short for grams per square metre. It is a measure of fabric weight. To find it, a factory cuts a piece of fabric and weighs it. The weight of one square metre of that fabric is the GSM.

The number does not measure the whole t-shirt. A large t-shirt and a small t-shirt from the same fabric have the same GSM. The large one is heavier only because it uses more fabric.

Factories use a round cutter for the test. The cutter takes out a circle of exactly 100 square centimetres. They weigh the circle and multiply the result by 100. A circle of 2.4 grams gives 240 GSM.

#The GSM ranges for t-shirts

Most t-shirt fabric falls into one of four ranges. The names are not official, but most Indian brands use them in the same way.

A number in the middle of a range does not change the feel much. The difference between 180 and 200 GSM is small. The difference between 160 and 260 GSM is easy to feel with your hand.

#Why GSM matters

GSM changes four things that you notice when you wear the t-shirt.

1. Thickness. A higher GSM fabric is thicker. Light passes through it less, so a white heavyweight tee is not see-through.
2. Shape. Heavy fabric holds its own shape. It falls straight from the shoulders. This is why oversized and boxy t-shirts use 220 GSM or more. A thin oversized tee clings to the body and looks like a size mistake.
3. Heat. Thick fabric keeps more heat. A 260 GSM tee feels warm in May in Delhi or Chennai.
4. Print quality. Heavy fabric gives a flat and stable base for prints. Puff print and screen print look cleaner on it.

#Is a higher GSM always better?

No. GSM tells you the weight of the fabric. It does not tell you the quality of the cotton.

Two fabrics with the same GSM can feel very different. The type of cotton changes the feel. Combed cotton (cotton with the short fibres removed) feels smoother and pills less than regular cotton. The knit also changes the feel. Single jersey (the common flat knit of t-shirts) is smooth. Loopknit and french terry have small loops on the inside and feel thicker.

The finish also matters. Bio-washed fabric (fabric washed with enzymes) feels softer. Pre-shrunk fabric changes size less after the first wash.

Use GSM to choose the weight you want. Then use the fabric details to judge the quality.

#Which GSM is best for Indian weather?

For most of India, the weather decides more than the style. Use this table as a start.

If you want an oversized fit in a hot city, choose 220 to 240 GSM. This weight keeps the shape but is not too warm.

#Why 240 GSM is the standard for oversized tees

Most Indian streetwear brands sell their oversized t-shirts at 240 GSM. There are three reasons.

First, 240 GSM is heavy enough to hang straight from a drop shoulder. A drop shoulder is a shoulder seam that sits below the edge of the shoulder. Second, it is light enough to wear in most of India for most of the year. Third, the number became a short way to say "premium" in product titles. Shoppers now search for it by name.

Some brands now go higher. You can find 260, 280 and 300 GSM tees. These feel close to a light sweatshirt. They are a good choice for winter in the North.

#How to check GSM at home

You cannot measure the exact GSM without a cutter and a scale. But you can test the weight in three simple ways.

1. Hold the tee up to a window. You can see a lot of light through 160 GSM fabric. You can see much less through 240 GSM fabric.
2. Hold the tee by the shoulders and let it hang. A heavyweight tee falls straight and keeps its shape. A light tee folds and clings.
3. Feel the collar. A heavyweight tee usually has a thick, tight neck rib (the stretchy band around the neck). A thin neck rib often comes with thin fabric.

If a product page does not show the GSM, ask the brand. Good brands answer in one line.

#GSM on a product page

When you read a product page, look for three facts together.

• The GSM number, for example 240 GSM.
• The fibre, for example 100% cotton or combed cotton.
• The finish, for example bio-washed or pre-shrunk.

A page that gives all three tells you most of what you need. A page that says only "premium fabric" tells you nothing.