There are two ways of fabric weight calculation. One is the weight per unit area such as GSM (grams per square meter) or oz / yd2 and another way is weight in running length.

Fabric Weight Calculation from Running Length: Calculate the GSM of the following technical textile fabric,

…120 x 70
……………………… x 58 …30 x 30

Answer:

For warp weight calculation

Here EPI is 120

Total number of ends = 120 x 39.37

Length of each end = 1 m + 1m x 0.03 (warp crimp% = 3%)
= 1.03m

Total length of warp yarn = 120 x 39.37 x 1.03 m

We get from the yarn numbering system,

……..L x W
Ne = …………. ……..W x l

………..L X W
∴ W = ……………..….. ….. …..Ne x l

….120 x 39.37 x 1.03 x 453.6
=……………………………………………….…. gm ……….40 x 840 x 0.9144

For weft weight calculation

Here, PPI = 70

Total number of picks = 70 x 39.37

Length of each pick = 1m + 1m 0.05 (weft crimp% = 5%)
= 1.05m

Total length of weft yarn = (70 x 39.37 x 1.05) meter

….70 x 39.37 x 1.05 x 453.6
= ………………………………………….………..gm ………30 x 840 x 0.9144

Total weight of the fabric per square meter,

….120 x 39.37 x 1.03 x 453.6 70 x 39.37 x 1.05 x 453.6
= ………………………..……………. + ……………………………….…….…….. ……….40 x 840 x 0.9144 30 x 840 x 0.9144

……120 x 1.03 70 x 1.05 39.37 x 453.6
= (…………………+ …………………) x .……………………………………… ………….40 30 840 x 0.9144

……120 x 1.03 70 x 1.05
= ( …………….. + ..……………….. ) x 23.25 …………40 30

……………….EPL x 1.03 PPI x 1.05
GSM = (……………….….. + …………………) X 23.25 ……………………Ne_{wa} Ne_{we}

Similarly,

oz/yd^{2} can be calculated by the following formula:

…………………EPI x 1.03 PPI x 1.05
oz/yd^{2} = (……………..….. + ……………..….. ) X 0.686 …………………….Ne_{wa} Ne_{we}

1.03 = For warp crimp (warp crimp % = 3%)

1.05 = For weft crimp (weft crimp % = 5%)

The crimp % for warp and weft can be changed. These two values normally applicable for maximum common fabric, although crimp% mainly depends on fabric structure.

Reference: Understanding Textile for A Merchandiser (Second Edition) by Prof. Dr. Engr. Shah Alimuzzaman Belal.