Fabric GSM is very important in the garment manufacturing industry. Every garment merchandiser should understand how to calculate fabric GSM correctly. Fabric GSM can be measured either by using a GSM cutter or by using other calculation methods based on fabric construction. In this guide, the focus is on the practical method of calculating fabric GSM by using a GSM cutter.
What is GSM?
GSM stands for grams per square meter. It is the standard unit used to measure the weight of fabric. The unit is written as g/m² or gm/m². In simple terms:
- A higher GSM means the fabric is heavier
- A lower GSM means the fabric is lighter
What is a GSM Cutter?
A GSM cutter is a circular cutting tool used to cut a fixed area of fabric for GSM testing. Normally, it cuts a sample equal to 1/100 of a square meter. Because the cut sample area is 1/100 m², the weight of that sample must be multiplied by 100 to find the actual fabric GSM.
GSM Calculation Method Using a GSM Cutter
The GSM calculation method using a GSM cutter is different from the theoretical method based on fabric construction. This method gives the actual measured GSM of the fabric.
Step 1: Cut the fabric swatches – Cut 5 swatches from different parts of the fabric using the GSM cutter.
Step 2: Weigh each swatch – Measure the weight of each swatch one by one using a weighing balance.
Step 3: Calculate the average swatch weight. Use the following formula:
- Average swatch weight = (1.2 + 1.4 + 1.3 + 1.1 + 1.5) ÷ 5
- Average swatch weight = 6.5 ÷ 5
- Average swatch weight = 1.3 g
Step 4: Calculate fabric GSM
- Fabric GSM = Average swatch weight × 100
- Fabric GSM = 1.3 × 100
- Fabric GSM = 130 g/m²
Example Summary:
- Suppose the weights of the 5 cut swatches are 1.2 g, 1.4 g, 1.3 g, 1.1 g, and 1.5 g.
- The average swatch weight is 1.3 g.
- The fabric GSM is 130 g/m².
- So, the fabric GSM measured by using a GSM cutter is 130 g/m².
Important Note:
The area cut by the GSM cutter is 1/100 m², which is why the average swatch weight is multiplied by 100. For better accuracy, swatches should be taken from different parts of the fabric, because GSM may vary across the fabric width or length.
Conclusion / Final Word
Using a GSM cutter is a simple, practical, and reliable method to measure the actual GSM of fabric. It is widely used in factories, fabric inspection, and quality control because it gives a direct result based on the real fabric sample. By cutting several swatches, weighing them carefully, and calculating the average, merchandisers and quality teams can get a more dependable GSM result.
