Fabric weight numbers show up on product labels, online listings, and spec sheets — and most people scroll right past them. That is a missed opportunity. Those numbers tell you more about how a fabric will feel, drape, and perform than almost any other spec on the page.
Fabric weight measures how heavy a set area of fabric is. The two most common units are GSM (grams per square meter) and oz/yd² (ounces per square yard). Silk uses its own system called momme. Once you know what the numbers mean, shopping for everything from t-shirts to bedding gets much easier.
GSM stands for grams per square meter. It tells you how much one square meter of fabric weighs. A higher GSM means denser, heavier fabric. A lower GSM means lighter, thinner fabric.
Think of it as a density score. Tighter weaves pack more fiber into the same area, which increases weight — and generally improves durability. A 300 GSM cotton feels noticeably thicker and sturdier than a 130 GSM cotton. You can feel the difference the moment you pick them up.
Oz/yd² (ounces per square yard) is the same concept in imperial units. It is primarily used in the United States. To convert, divide GSM by 33.906. So a 200 GSM fabric is roughly 5.9 oz/yd². Most product listings outside the US use GSM, which is why I recommend getting comfortable with that number first.
One thing worth knowing: GSM is not perfectly comparable across different fabric types. A 200 GSM knit fabric and a 200 GSM woven fabric will feel quite different in your hands. Knit fabrics use more yarn in their construction and often include spandex or lycra, which adds weight without adding stiffness. So a knit can read higher on the scale yet feel lighter and stretchier than a woven fabric at the same GSM. Keep that in mind when comparing across fabric categories.
Most woven and knitted cloth spreads across a familiar ladder. It runs about 120-170 GSM for warm-weather fabrics, 170-280 GSM for everyday garments, and 280 GSM upward for anything built for structure or warmth. Sheer fabrics like chiffon and organza fall below 100 GSM, which is why they are translucent.
Silk starts at the bottom of that ladder and keeps going down. A 19-momme silk pillowcase is about 82 GSM. A 12-momme scarf is closer to 52.
Put those next to a 180 GSM t-shirt and the ladder stops being useful. The differences that matter between two silks are a few grams apart, and GSM rounds them into the same bucket. Silk keeps a unit of its own, the momme, inherited from the Japanese silk trade.
If you have ever shopped for silk products, you have probably seen a different number: momme (pronounced “mommy”). Silk uses its own weight measurement because the silk trade inherited the momme, a traditional Japanese unit of weight.
One momme roughly equals 4.34 GSM. So when a silk pillowcase says “22 momme,” that translates to about 95 GSM — which sounds lightweight for cotton, but is actually considered premium weight for silk.
Here is how momme ranges map to silk products:
| Momme | GSM (approx.) | Feel | Best For |
|---|---|---|---|
| 10-14 | 43-60 | Sheer, delicate | Scarves, lightweight blouses, linings |
| 16-19 | 69-82 | Smooth, mid-weight | Sleepwear, everyday pillowcases, shirts |
| 22-25 | 95-108 | Luxurious, substantial | Premium pillowcases, sheets, quality apparel |
| 28-30 | 120+ | Dense, heavy | Upholstery, ultra-luxury products |
For most silk purchases — pillowcases, pajamas, scarves — the 16-22 momme range hits the best balance of feel, durability, and value. Higher momme silk is denser and more durable, but also more expensive and less breathable. A 19-momme silk pillowcase will feel smooth and last well without being excessively warm.
The honest truth about momme: a higher number does mean more silk per area, which generally means more durability. But jumping from 22 to 30 momme raises the fabric density by about a third and adds cost while making the silk noticeably heavier and warmer. For a summer scarf, 12-14 momme is perfect. For a pillowcase that needs to withstand nightly friction, 19-22 momme is the practical sweet spot. Match the weight to the product, not to the highest number.
No. This is the most common misconception I run into. Heavier does not equal better — it equals different.
The mismatch is easiest to see at the extremes. A 400 GSM t-shirt is a light jacket, and a 120 GSM bath towel does not absorb. In both cases the fiber can be excellent and the product still wrong.
Silk fails the same way, just over a narrower range. A 30-momme scarf is dense enough to hang stiffly and sleep warm, which is the opposite of what a scarf is for. A 12-momme pillowcase feels beautiful in the shop and will not survive a few hundred nights of friction at the same spot.
Weight tells you about density, not quality. Quality comes from fiber type, yarn construction, and finishing. A 60 GSM silk outlasts a 300 GSM polyester in drape and feel because of what the fiber is, not how much of it there is.
So the question is never which number is highest. It is whether the weight matches the job, and every product category has its own answer.
Next time a weight number appears on a listing, run it through two checks.
First, identify the unit. If it is momme, you are looking at silk and the momme table above is the reference.
If it is GSM on something sold as silk, divide by 4.34 to get back to momme. A listing that quotes GSM for silk is usually a synthetic borrowing the word.
Second, ask whether the weight fits the job. Sixteen to 19 momme is the working range for sleepwear and everyday pillowcases; 22 to 25 is where pillowcases and sheets stop showing wear; 12 to 14 is a scarf that drapes instead of hanging.
A listing that gives you neither a momme number nor a fiber content is telling you something by omission. When we quote custom silk fabric by the meter, momme comes first, because it is the spec that decides how the finished piece behaves.