Calculating Fabric Weights

Finding out the exact weight of a fabric can be a little tricky at times and it doesn’t help matters when one company may use a slightly different method than another. We need to know the weight of the fabric before working with it, this is even more important when buying fabric online when you can physically feel the fabric.

If you are not familiar with a fabric, knowing the weight will give you a little more insight. The weight will hold clues as to what you can achieve with the fabric, what you could make out of the fabric, what patterns would be better, how the fabric may hang, and what needles to use. Materials are often placed into a loosely defined set firstly, to give a generalised idea about the weight.

Heavy Weight Fabrics

Medium Weigh Fabrics

Lightweight Fabrics

These categories give some help to guide you, but many fabrics don’t quite fit neatly into these categories!

This is the point when a little more knowledge is needed. There is a widely used method for calculating the weight of a fabric which to some may seem slightly tricky to grasp. Below is a simplified breakdown of the method along with the terms that are used to describe it.

GSM (Grams Square Metre)

This is a metric measurement meaning grams per square metre, sometimes written as gm/m2. You can calculate the GSM in a few ways. The most simple is to weigh one square metre of the fabric yourself, though most manufacturers will calculate this before the fabric goes on sale its good practice to double check. Generally speaking the higher the GSM the denser the fabric will be, although you still have to use your own initiative with some more unusual fabrics such as fabric with holes and textural patterns, the density will of course vary with these.

OZ (Ounces)

Ounce per square yard (oz/sq2) is the imperial measurement which is also commonly used. A lightweight fabric is typically between 30- 150 GSM, medium weight 150-350 GSM and heavyweight 350+ GSM, such as our clear window PVC (640 GSM), although this can vary depending on the type of fabric.

Conversions.
If a fabric you have has the weight in GSM and you need OZ per square yard there are plenty of converters online to help you. These may look rather complicated at first but as long as you have a calculator handy, you will be fine!

GSM Cutter

Another way of measuring the GSM is by using a GSM cutter. These hand held round cutters simply cut a piece of fabric which is the same every time so there is nor discrepancies. When five circles are cut they are placed on a weighing scale to gauge an average weight. Then multiply the average weight of swatches by 100 to calculate GSM of the sample fabric.

Grams Square Metre (GSM) Circular Fabric Cutter
Grams Square Metre (GSM) Circular Fabric Cutter

 

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