What is Fabric GSM and How to Measure It

When we’re out to buy fabric for our crafting needs, one term we often hear is fabric GSM. Even when you take a close look at the hang tag of a garment, you’ll see it there. It’s a very important attribute of a garment because along with many other factors the price and comfort depend heavily on it. Also, different type of knitting stitches and woven structures give rise to different GSM values.

In this article, we’ll provide you an in-depth look into what is fabric gsm and how do we measure fabric gsm.
Without further ado, let’s jump right in.

GSM stands for “Gram per Square Meter.” Therefore, we can say it’s a measure of fabric density, i.e., the weight of the fabric per square meter. By evaluating the fabric GSM value, we can assess whether the fabric is heavy or lightweight. The higher the GSM, the heavier it weighs and vice versa. It’s an essential parameter in the textile sector for obvious reasons.

We can’t characterize a fabric without mentioning it. We can measure GSM for all types of fabrics. It’s an essential parameter of the garments ordering process. Thus, maintaining it in all stages of the production is of utmost importance. For this, every textile engineer, specially merchandiser of woven and knit garments, should know the GSM calculation to execute the order properly.

Now, we must remember that while fabric GSM gives us the idea of its weight it’s not a clear indicator of its thickness. The fabric thickness mainly depends on its structure/ construction.

During the calculation of fabric GSM, the crimp factor may be needed sometimes, and for that reason, we have to know the crimp percentage.

Warp and weft yarns are used to form fabrics. These two sets of threads, i.e., warp and weft yarns, create the structure of cloth by interlacing with each other. Due to the interlacing of these two sets of yarn, a wavy structure formed. This waviness is called Crimp. And Crimp always expressed in percentage. Here, the yarn loses its length while forming a wavy formation.

The normal length of the yarn is longer than the interlaced one. That means the threads that are used to create interlacing lose its length due to wavy formation. Suppose a yarn whose length is 5.5 meter in normal or in straight condition, but when it interlaces with another one and form a fabric, then it loses its length, and the length is 5 meter(0.5 meter loss).

For measuring the GSM, we need to measure the crimp percentage first. The measurement of warp crimp and weft crimp percentages formula are mentioned below:

You need to use the following equation to get the crimp% of the warp –

Crimp% of Warp Yarn = {(Length of the Warp in Straight Condition – Length of the Warp in Fabric Formation) ÷ Length of the Warp in Fabric Formation} × 100

You need to use the following equation to get the crimp% of the weft –

Crimp% of Weft Yarn = {(Length of the Weft in Straight Condition – Length of the Weft in Fabric Formation) ÷ Length of the Weft in Fabric Formation} × 100

We can use this formula to determine the GSM of given woven fabric:

Woven Fabric GSM = [{(Ends Per Inch × Warp Crimp Factore) ÷ Warp Count} + {(Picks Per Inch × Weft Crimp Factore) ÷ Weft Count}] × 23.5

Now by putting down all the value from a sample, we can easily determine GSM value for a woven fabric.

We can use either of these formula to determine the GSM for knit fabric:

Fabric GSM with Direct Count(Tex) = Course Per Inch × Wales Per Inch × Stitch Length in mm × Yarn Count in Tex × 0.001549

Fabric GSM with Indirect Count(Tex) = (Course Per Inch × Wales Per Inch × Stitch Length in mm × 0.9155) ÷ Yarn Count in Ne

Basically, the GSM cutter machine works through its Four highly sharp blades. The blades are fitted inside the machine and sorted out in a pattern as every blade can participate in cutting in sequential order and cut the fabric very smoothly. A plate covers the outer part in which blades lie inside. As the blades are highly sharp, so we have to be careful while cutting fabric.

There are machines of various diameters, but for use in textiles, the ideal diameter is about 11.2 cm.

A cutting pad is an inescapable item for GSM cutter. It is also known as GSM PAD. GSM pad is mainly used to avoid crinkles and crease from the fabric during cutting. It helps to get the actual value of GSM.

Actually there are two methods for measuring GSM; one with a GSM cutter and the other without it. Here, we’ve discussed the method with the GSM cutter. But if you don’t have a GSM cutter, then read our article on how to find GSM of fabric without GSM cutter.

Step 1: Condition the Fabric

Firstly, take a sample from the main fabric and reserve it for conditioning. The conditioning time may vary from fabric to fabric because it depends on the nature of the fabric.

Step 2: Placing It over the GSM Pad

When the conditioning time is over, then the fabric is placed on the GSM pad to avoid crinkle and crease. Then the GSM cutter is placed on the fabric.

Step 3: Cut the Fabric

Now, with the hand-driven metal knob, we have to cut the fabric, maintaining a steady pressure. And thus, the fabric is finally cut into 11.2 cm in diameter.

Step 4: Weigh the Fabric

Then we have to move the machine and take the fabric for weighting on the electronic balance to have an accurate measurement.

Step 5: Calculate the GSM

The formula for measuring GSM by GSM cutter machine:

GSM= Specimen weight(gm) × 100

After weighing the value of the cut specimen, we have to multiply the value with 100 and then calculate it. The calculated result is the GSM value for the fabric.

Important Notes

For more accuracy, we should cut the fabric sample from five different places of the main fabric and measure the weight. After calculating the mean value, we have to multiply it by 100 just like before.

N.B. Thread count 80 wt means 80 kilometers of that thread weighs 1 kilogram.

Hopefully after reading this article, now you have a clear idea of what is fabric gsm and how you can calculate it.

References

1. oschaslings.com
2. What is GSM | GSM in Textile Industry
3. How to Check Fabric Weight?