GSM stands for grams per square metre. It is the standard way to measure the weight of a fabric: take one square metre of cloth, weigh it, and the result in grams is its GSM. A lightweight summer tee might sit around 150 GSM, while a heavyweight hoodie can be well over 400.

Fabric weight is one of the most useful numbers on a product page, yet it is often misunderstood. This guide explains what GSM means, what typical weights look like and what weight can and cannot tell you about a garment.

How GSM is measured

Manufacturers cut a precise circle or square of fabric, weigh it on a calibrated scale and scale the result up to one square metre. The figure describes the fabric itself, not the finished garment, so two hoodies made from the same 345 GSM cloth will weigh differently if one is longer or has a bigger hood.

You may also see fabric weight given in ounces per square yard, especially for denim. As a rough conversion, one ounce per square yard is about 34 GSM.

Typical GSM ranges

There is no official scale, but the industry broadly uses these bands for knitted fabrics:

• Lightweight, under about 180 GSM: summer tees, fine jersey, base layers.
• Midweight, about 180 to 300 GSM: heavier tees, lighter sweatshirts, many joggers.
• Heavyweight, above about 300 GSM: sweatshirts, hoodies and winter pieces with a substantial hand.

Woven fabrics such as shirting and tailoring cloth follow their own conventions, and silk is often measured in momme, a separate unit specific to silk.

GSM across the Parhela collection

To give the numbers some context, here is how weight varies across our pieces:

• The Pearlescent Tee is cut from a 200 GSM Italian fabric with a natural silky sheen.
• The Flight Suit Top uses a 265 GSM Portuguese modal.
• The Breton is a plush 330 GSM Italian cotton fleece.
• The Terry Shorts use a 340 GSM Italian towelling.
• The Staple Hoodie and the Wild Window pieces are cut from our 345 GSM Italian loopback cotton.
• The Snoodie uses a 375 GSM Italian loopback.
• The Celestial pieces use a 445 GSM Italian wool blend.
• The Lined Hoodie reaches 580 GSM and weighs over a kilo when finished.

What a higher GSM gives you

A more substantial feel

Heavier fabrics feel denser in the hand and hang differently on the body. A heavyweight sweatshirt holds its shape rather than clinging, which is why it often looks more structured.

Durability

All else being equal, a denser fabric tends to resist stretching, thinning and holes for longer. That makes weight a useful indicator of how well a piece might age.

Warmth

More fabric usually traps more air, so heavier pieces are generally warmer. If warmth is your priority, our guide to heavyweight hoodies goes into more detail.

What GSM does not tell you

Weight is useful, but it is only one part of the picture.

• Fibre quality. A heavy fabric made from short, coarse fibres can pill and feel rough. Long-staple fibres, like those in Pima cotton, make a softer, stronger cloth at any weight. See what makes Pima cotton worth it.
• Knit construction. Loopback, fleece and jersey of the same weight behave very differently. Our guide to loopback cotton versus fleece explains why.
• Breathability. Some heavy fabrics trap heat; others, thanks to their construction, stay breathable. Our Lined Hoodie was designed to make the wearer feel cocooned whilst still maintaining breathability.
• Finishing. How a fabric is dyed, washed and finished changes its hand and how it ages.

In other words, a higher number is not automatically better. A 200 GSM tee from an excellent mill can outlast and outperform a 250 GSM tee made from poor cotton.

How to use GSM when shopping

1. Match weight to purpose. Choose lighter weights for layering and warm weather, heavier ones for outerwear-like hoodies and winter sweatshirts.
2. Compare like with like. Compare a hoodie with other hoodies, and a tee with other tees.
3. Look beyond the number. Check the fibre, the knit and where the fabric comes from. Mills with long histories tend to produce more consistent cloth; we explain our approach in why we source our fabrics from Italian mills.
4. Think about construction. Heavy fabrics need stronger seams and ribbing. On the Lined Hoodie, we had to create a specific type of ribbing to match the thickness of the fabric.

GSM and longevity

Fabric weight is closely linked to how long a garment lasts, which in turn shapes its real cost. A heavier, well-made sweatshirt worn hundreds of times costs less per wear than a cheaper one replaced every season. We explore that maths in what a £15 T-shirt and a £400 hoodie are really paying for.

In short

GSM means grams per square metre and measures how heavy a fabric is. Under about 180 GSM is lightweight, 180 to 300 is midweight and above 300 is heavyweight. A higher GSM usually means a more substantial, durable and warmer fabric, but fibre quality, knit construction and finishing matter just as much. Across our collection, weights range from the 200 GSM Pearlescent Tee to the 580 GSM Lined Hoodie. Compare them in our jumpers and hoodies.