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GSM Calculator for Fabric Weight

GSM, grams per square metre, is the number everyone quotes when buying or selling fabric. This calculator turns a weighed sample into GSM and then into the figures purchasing and logistics actually use: ounces per square yard, grams per metre, metres per kilogram and roll weight.

Your numbers

Sample weight

Weight of the cut sample after conditioning.

Sample area

cm2

A standard round cutter gives 100 cm2.

Fabric width

Roll length

Your results

GSM

180

Grams per square metre.

Metres per kg

3.7037

Ounces per square yard

5.3088

1 oz/yd2 is about 33.906 g/m2.

Grams per linear metre

270

Roll weight

21.6

Estimated net roll weight in kilograms.

Results depend on sample accuracy. Test per your agreed method, for example round cutter sampling at several roll positions.

Save results:

Metres per kg vs sample weight

Sweeps Sample weight from 1 to 3, holding your other inputs fixed.

Lot test data in your ERP

Optional: a short guide to storing fabric lot attributes like GSM and width in your ERP.

Optional. The tool and every export work without this. No spam.

How to measure

Cut a sample with a round GSM cutter, which gives a known area, often 100 square centimetres. Weigh it on a balance accurate to 0.01 gram. Take samples from several positions across the width and along the roll, then average. Enter the average weight and area. Make sure the fabric is conditioned, since moisture changes weight, especially in cotton.

Avoid the first and last metres of the roll.
Cut away from selvedges unless testing selvedge weight.
Record the conditioning atmosphere used.

Formulas and conversions

GSM equals sample weight in grams divided by sample area in square centimetres times 10,000. Ounces per square yard equals GSM divided by 33.906. Grams per linear metre equals GSM times width in metres. Metres per kilogram equals 1,000 divided by grams per linear metre. Roll weight is grams per metre times the length. Knit fabrics are often sold by weight and woven by length, so these conversions are used constantly.

Reading the result

Compare your GSM against the buyer specification and its tolerance, often plus or minus five percent. Very light jersey sits around 120 to 150 GSM, mid-weight tees around 160 to 200, fleece and heavy knits well above that. If GSM varies widely across the width or roll, the finishing or knitting process needs attention.

Common mistakes

Weighing samples before conditioning, using the label width rather than the measured width for linear weight, and mixing finished GSM with greige GSM are the common errors. State whether the number is greige, dyed or finished when you share it.

Frequently Asked Questions

How do I calculate GSM of fabric?

Weigh a sample of known area and divide the weight in grams by the area in square centimetres, then multiply by 10,000. A 100 cm2 sample weighing 1.8 g gives 180 GSM.

How do I convert GSM to oz per square yard?

Divide GSM by 33.906. For example, 200 GSM is about 5.9 oz per square yard. For the reverse, multiply ounces per square yard by 33.906.

How do I get metres per kg from GSM?

Multiply GSM by fabric width in metres to get grams per linear metre, then divide 1,000 by that number. Wider or heavier fabric gives fewer metres per kilogram.

What tolerance is normal for GSM?

Many specifications allow around five percent either way, but it depends on the buyer and the fabric. Always check the agreed specification or test standard on the order.

Netray can help bring fabric lot test results such as GSM and width into the item and lot records in your ERP so purchasing and quality use the same numbers.

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