Fabric Weight

GSM is commonly found when shopping for fabric online. GSM stands for grams per square meter. It is the metric measurement of the weight of a fabric or how much 1 square meter of that fabric weights. The higher the number, the heavier or denser the fabric is. Patterns will usually call for either lightweight, medium or heavy weight fabrics to be used. The imperial equivalent is ounce (OZ) per square yard which is usually simply referred to as OZ. Denim is often described using OZ.  

The weight of a fabric doesn’t determine its quality, but it can reflect its opacity, fluidity and sturdiness. As a general guideline, a heavier fabric will yield a more structured garment, may not need interfacing and would probably be more durable. A type of fabric can presents various weight. For example, linen can range from lightweight (around 100 GSM, sheer and more suitable for summer tops and blouses), medium weight (around 200 GSM, opaque and suitable for clothing and heavy enough for pants) to heavy weight (for home decor applications). The composition (i.e. cotton, rayon, bamboo, spandex, etc.) and whether it is a woven or a knit fabric will also affect the weight.

The following table summarizes the weight categories and GSM ranges to expect.

Weight Category

GSM Range

OZ Range


50 – 170

1.5 – 5.0

Medium Weight

170 – 340

5.0 – 10.0

Heavy Weight

340 +

10.0 +


In summary, GSM info is provided to help guide the choice of fabric online without being able to touch and feel it, but it can’t be used to assess all the qualities of a particular fabric.