Fabrics are the main components of garments. The garment's weight and cost depend on the fabric GSM. In the garment sampling stage and pre-production, it is essential to know the accurate GSM of the fabric that will be used for making the garment. In the FOB order, if you use a fabric of higher GSM than the approved one based on which material costing is estimated, actual material cost per garment will increase. We have two options to determine the fabric GSM. The first one is the use of a GSM cutter and weighing balance. Which is the most common method of GSM estimation? The other method is calculating fabric GSM from its construction. This method applies to woven garments. In this article, you will learn the second method for fabric GSM calculation.
To calculate the approximate GSM (grams per square meter) of a given fabric, use the formula shown below. Normally, this method is suggested when you don't have access to the GSM cutter and you need to know tehe GSM of the fabric swatch or fabrc sample.
One of my colleagues used to use this formula in the testing lab. If different counts of warp thread or weft thread are used, then this formula will not give you the correct GSM. It is also known as a conversion formula from fabric construction to fabric weight.
GSM calculation Formula:
Fabric GSM = (EPI/Warp Count + PPI/Weft Count) x (100 + Crimp %) X 0.2327
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| Woven Fabric |
To use this method, you must have infomation of fabric construction deatils and fabric count.
Fabric GSM = (120/40 + 60/40) X (100+6%) X 0.2327
Fabric GSM = 104.77
Also See: What is Crimp% in Fabric and How to Measure Warp and Weft Crimp%
I found others use this formula with different multiplying factors.
Fabric GSM= ((EPI/warp count X 1.1) + (PPI/weft count x 1.04)) x 23.5 By Dharmi
In the above formula, 1.1 and 1.04 are warp and weft crimp factors, respectively.