Finding out exact fabric weights 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, therefore you can get a better idea of what you can do with it. Knowing the weight is even more important when buying fabric online when you can physically feel the fabric.
If you are buying a new fabric you havnt worked with before, knowing the weight will give you a little more insight. Fabric weights 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.
Medium Weigh Fabrics
These categories give some help to guide you, but many fabrics don’t quite fit neatly into these categories! At this point 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 simple breakdown of the method along with the terms that are used to describe it.
GSM (Grams Square Metre)
GSM 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 for yourself. 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 can vary with these.
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.
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!
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 no mistakes. When you have cut five or six circles, place them on a weighing scale to find out the average weight. You then need to multiply the average weight of swatches by 100 to calculate GSM of the fabric.