This calculator works out knit fabric GSM from the yarn and the loop. Use the first mode when you have a fabric sample and can count courses and wales. Use the second to estimate single jersey GSM before knitting, from the count and stitch length alone.
How it works
- GSM = courses/cm × wales/cm × stitch length (mm) × tex ÷ 100.
- Tex = 590.5 ÷ Ne, or denier ÷ 9.
- Double knits (rib, interlock): count the wales on one face and the calculator doubles the loops.
- Estimate mode: courses/cm = Kc ÷ stitch length (cm) and wales/cm = Kw ÷ stitch length (cm). The default constants are typical for relaxed cotton single jersey.
Greige, dyed and finished fabric give different counts, because the loops relax and shrink in wet processing. Count on the fabric in the state you want the GSM for. Elastane adds weight that this formula does not include; check Lycra fabric against a weighed sample.
Questions
What is the formula for knit fabric GSM?
GSM = courses per cm × wales per cm × stitch length (mm) × yarn tex ÷ 100. For double knits such as rib and interlock, count the wales on one face and multiply by 2.
How do I convert Ne to tex?
Tex = 590.5 ÷ Ne. For example, 30 Ne cotton is 590.5 ÷ 30 = 19.7 tex.
Can I estimate GSM before knitting?
Yes, for single jersey. In a relaxed fabric, courses and wales per cm are close to fixed constants divided by the stitch length, so GSM can be estimated from count and stitch length alone. Check the result with a knitted sample.