GSM in Satin: What Fabric Weight Means and How to Measure It

What does GSM mean for satin?

GSM means grams per square metre: the weight of one square metre of fabric. It is the standard way to say how heavy a fabric is, whatever its fiber, and it lets you compare a silk satin, a polyester satin and a heavy duchess satin on the same scale. A light satin lining may be around 60 GSM, a blouse satin around 90 and a bridal duchess well above 200. The number tells you weight, not quality.

ASTM International’s test method D3776 covers the measurement of fabric mass per unit area, which it notes is traditionally called fabric weight, and it offers four options: a full piece, a full-width sample, a small swatch, and narrow fabrics (ASTM D3776, Mass per Unit Area (Weight) of Fabric). The ISO standard for woven fabrics is ISO 3801. Both exist because the same fabric can be reported in several ways, and a shop’s number may not match your own scale. This guide explains the units, gives a working converter, shows how to measure GSM at home, and explains what the number can and cannot tell you.

How do GSM, momme and ounces per square yard convert?

Multiply momme by 4.34 to get GSM, and divide GSM by 33.906 to get ounces per square yard. The momme figure comes from the Norwegian encyclopedia Store norske leksikon, which gives 1 momme as 4.34 grams per square metre of silk fabric (Store norske leksikon, momme). The ounce figure follows from exact definitions: an avoirdupois ounce is 28.3495 grams and a yard is exactly 0.9144 metres, so a square yard is 0.8361 square metres, and 1 oz/yd2 is 33.906 g/m2.

Fabric sold by the linear yard adds width. A fabric at 3 oz per square yard that is 45 inches wide (1.25 yards) weighs 3 x 1.25 = 3.75 oz per linear yard. A 140 cm wide fabric at 100 GSM weighs 1.4 x 100 = 140 g per linear metre. Always check whether a listing means per square or per linear unit before you compare two fabrics. If this is your question, see our guide to heavyweight satin.

How do you measure GSM at home?

Cut a 10 cm by 10 cm square, weigh it, and multiply the grams by 100. A 10 cm square is 0.01 square metres, which is one hundredth of a square metre, so the weight in grams multiplied by 100 gives grams per square metre. If the swatch weighs 0.82 g, the fabric is about 82 GSM, which is about 19 momme.

1. Press the fabric flat and let it rest in the room for an hour so it is at room humidity.
2. Mark a 10 cm square with a ruler and a set square, away from the selvage. The selvage is the tight edge of the cloth and can weigh differently from the body.
3. Cut along the marks with sharp scissors or a rotary cutter, and keep the edge straight.
4. Weigh the swatch on a kitchen scale that reads to 0.01 g. A scale that only reads to 1 g is too coarse for light fabrics.
5. Multiply the weight in grams by 100. Repeat on two or three other spots and average them, because weight varies across a roll.
6. Convert the result with the converter above if you want momme or ounces.

Know the error. A cutting mistake of 1 mm on each side changes the area by about 2 percent (101 squared over 100 squared is 1.02), which moves an 82 GSM result by about 1.6 GSM. A scale that rounds to 0.01 g on a 0.8 g swatch is accurate to about 1 percent. Moisture matters too, since fibers take up water. The ASTM method conditions fabric before weighing, so a home result will not match a lab report exactly. It is still good enough to compare one fabric with another.

What GSM is light, medium or heavy satin?

There is no official standard, so use bands as a working guide. On this site we use the following bands for satin garments and furnishings. Treat them as a way to compare, not as a rule from a standards body.

Retail wording differs. Silk sellers call 19 to 22 momme (about 82 to 95 GSM) a mid weight, because they compare it with other silk. By the bands above it falls in the light range, because it is compared with all satin. Neither is wrong. They are using different yardsticks, so always compare numbers, not adjectives.

Does a higher GSM mean a better satin?

No. GSM measures weight per area, not quality. A heavy satin can be thick because it uses coarse yarn, a loose weave or a heavy finish. A light satin can be fine and tightly woven. The fiber, the yarn size, the number of yarns per centimetre and the finishing all matter, and GSM captures only the total.

• Same GSM, different fiber. A 90 GSM polyester satin and a 90 GSM silk satin weigh the same, but silk takes up moisture and drapes differently. See silk satin and polyester satin.
• Same fiber, different GSM. A heavier silk satin is more opaque and durable, and a lighter one is more fluid and more fragile.
• Weight can hide thin weaving. A heavy, loosely woven satin can look good in a photo and fray quickly. Check the yarn density and the hand, not just the number.

How does GSM change drape, opacity and warmth?

Heavier fabric hangs lower, shows less through it, and feels warmer. Light satin flutters, clings and can be see-through in pale colours. Heavy satin holds a shape and hides the lining, but it can feel stiff and hot. The effect depends on stiffness as well as weight, so two fabrics of the same GSM can drape quite differently.

• Drape. A light, fluid satin falls in small folds. A heavy one falls in larger, rounder folds, and a stiff one holds a shape.
• Opacity. More fabric per area blocks more light. Pale colours show through at lower weights than dark ones.
• Warmth. More fabric per area traps more air, and polyester satin traps heat at any weight.
• Price. Heavier fabric uses more fiber and costs more to buy by the metre, but it may last longer.

Which GSM suits which use?

Pick the weight by what the fabric has to do, then check fiber and weave. The ranges below are practical starting points, not rules.

Buying by the metre? Our guide to buying satin by the yard covers widths, cuts and what to ask the seller.

How does GSM relate to yarn size and thread count?

GSM is what you get when you add up every yarn in a square metre. For a woven fabric, the weight comes from the yarn count in each direction and the weight of each yarn. A simple estimate is GSM = (warp yarns per cm x warp yarn weight in tex x crimp allowance + weft yarns per cm x weft yarn weight in tex x crimp allowance) divided by 10. Tex is the weight in grams of 1,000 metres of yarn, and crimp allowance, usually a few percent more, accounts for the yarn bending over and under the others.

Here is an illustrative example, not a real fabric. Suppose a satin has 60 warp yarns per cm at 5 tex (about 45 denier) and 40 weft yarns per cm at 7 tex (about 63 denier), with a 6 percent crimp allowance. The warp contributes 60 x 5 / 10 = 30 GSM and the weft 40 x 7 / 10 = 28 GSM, so 58 GSM, and with crimp about 61 GSM. Double the number of yarns, or use yarns twice as heavy, and the GSM roughly doubles.

This also shows why thread count and GSM are not the same. Thread count counts yarns per unit width. GSM also counts how heavy each yarn is. A high thread count of very fine yarn can weigh less than a low thread count of thick yarn. When a seller quotes only one of the two, you know only half the story.

How do you compare price per square metre?

Fabric is usually priced per metre of length, but the width changes how much cloth you get. To compare fairly, divide the price by the width in metres to get a price per square metre, then divide by GSM if you want a price per kilogram. Suppose a satin costs 12 per metre at 1.4 m wide and another costs 9 per metre at 1.1 m wide. The first is 12 / 1.4 = 8.57 per square metre, and the second is 9 / 1.1 = 8.18. The second looks cheaper per metre of length and per square metre, but if its GSM is lower, you may be buying less fabric by weight.

Price per kilogram is useful because it compares fiber content directly. Take the price per square metre, divide by GSM, and multiply by 1,000. A fabric with a much higher price per kilogram than similar fabrics may be carrying a premium for finishing, brand or fiber. Silk is expensive per kilogram, while polyester is far cheaper, which is part of why GSM alone does not tell you the cost.

Why do sellers’ GSM numbers differ from yours?

Reports differ for several ordinary reasons. Test methods specify how to treat the selvage and how to condition the fabric, and the same fabric can weigh slightly different amounts at different humidity. Rounding, width and the part of the roll that was sampled also matter. Some sellers quote the weight before finishing, some after, and some quote momme for polyester, which is not a standard use of the unit. If a listing does not say how the number was measured, treat it as an estimate and check it against a swatch.

What mistakes do people make when reading GSM?

Most mistakes come from treating the number as a quality grade or from comparing numbers measured in different ways. Four come up again and again:

• Comparing silk momme with polyester GSM as if they were the same scale. They convert, but the fibers behave differently at the same weight.
• Mixing up per square and per linear units. A 45-inch fabric and a 60-inch fabric of the same ounce weight per linear yard are different fabrics.
• Assuming heavier is warmer or better. It is heavier, nothing more, and the fiber and weave decide the rest.
• Trusting a single number. One measurement can be off by a few percent, so average several spots on the cloth.

What should you check before you buy by GSM?

1. Whether the number is per square or per linear unit, and in which units.
2. The fiber content on the label, because GSM does not tell you the fiber.
3. The yarn density or thread count, if listed, and the handle in a swatch.
4. The opacity in your colour, using a swatch against your skin or the intended lining.
5. The care label, because weight and fiber decide how it washes.
6. The return policy, so you can check the weight on your own scale.

Why should you trust this guide?

We do not sell fabric and earn nothing from any brand named here. The conversion between momme and GSM comes from Store norske leksikon, the ASTM method is described on ASTM’s own page, and the ounce conversion follows from exact unit definitions. The measuring method and the error figures are our own arithmetic from the definition of GSM. The weight bands are this site’s working guide, not an industry standard, and the use table is practical guidance. We could not open the full text of ASTM D3776 or ISO 3801, which are paid standards, so we do not describe their procedures in detail. We did not test fabrics for this guide.

Frequently asked questions

What is a good GSM for satin?

It depends on the use. Around 70 to 110 GSM suits blouses, pajamas and pillowcases, 100 to 180 GSM suits dresses and skirts, and 160 GSM and above suits formal gowns and drapery. Check the fiber and weave as well as the number.

Is GSM the same as momme?

No, but they measure the same thing in different units. GSM is grams per square metre, and momme is a silk weight unit. One momme equals 4.34 GSM, so 19 momme is about 82 GSM.

How do I convert ounces per square yard to GSM?

Multiply by 33.906. For example, 3 oz per square yard is about 102 GSM. To go the other way, divide GSM by 33.906.

Does higher GSM mean more durable satin?

Often it means more fabric to wear out, but not always. A heavy, loosely woven satin can wear poorly, and a light, tight one can last well. Fiber, weave and finish matter as well.

Can I measure GSM without a special scale?

You can get a rough figure with a kitchen scale that reads to 0.01 g and a 10 cm square swatch. A scale that reads only to 1 g is too coarse for light satin, so use a larger swatch, such as 20 cm by 20 cm, and multiply by 25.

Why does the same fabric have different GSM on different sites?

Differences come from measurement method, humidity, rounding, finishing and the part of the roll that was weighed. Treat numbers from different sellers as approximate, and compare them using the same method.

What GSM is see-through satin?

Pale, light satin below about 70 GSM often shows through, especially in white and pastel colours. Dark colours and fabrics with a tight weave stay opaque at lower weights. A lining solves it.

Is a heavier satin warmer?

Usually, because it traps more air and covers more of the skin. Polyester satin can feel warm at any weight because it does not absorb moisture. Silk and a loose cut are better for warm sleepers.

Final word

GSM is the most useful single number on a satin listing, as long as you remember what it does and does not say. Convert it into units you understand, measure a swatch when the stakes are high, and read it together with the fiber and the weave. For the silk side of the same measure, see our guide to momme, and for how weight changes the way satin hangs, see our drape and shine guide.