Momme: What the Silk Weight Means and Which Number to Look For
Buy silk and sooner or later you meet a figure like “19 momme” or “22 momme”. It sits right next to the product name and is rarely explained, yet it is one of the most telling specs a silk product carries: in short, a measure of how heavy the fabric is. This guide covers what momme means, how it converts to grams per square metre, why silk is measured by weight rather than thread count, and which number makes sense for what.
What does momme mean?
Momme (mm) is how the weight of a silk fabric is measured. The unit comes from Japan, and it sets a figure for how much silk sits in a given area. In practice, one rule of thumb is enough: 1 momme equals roughly 4.34 grams per square metre. A fabric at 22 momme therefore weighs about 95 grams per square metre.
The higher the momme, the more silk fibre sits in the same area. The fabric is either more densely woven or made from heavier threads; it hangs with a heavier drape and feels more substantial. A low number means a lighter and usually more sheer material.
Stated precisely: one momme is the weight in pounds of a piece of silk 100 yards long and 45 inches wide, which converts to 4.34 grams per square metre. That sentence and the table below are the whole of the unit.
| Momme | Weight (g/m²) | Hand and drape | Opacity | Where you meet it |
|---|---|---|---|---|
| 12 | 52.1 | very light, airy, fluid | sheer, clearly translucent | scarves, linings, light blouses |
| 16 | 69.4 | light, soft, still fluid | slightly translucent | blouses, dresses, light bedding |
| 19 | 82.5 | medium weight, supple | largely opaque | the usual entry point for pillowcases and bedding |
| 22 | 95.5 | dense and substantial, still flowing | opaque | the established standard for silk pillowcases |
| 25 | 108.5 | noticeably heavy, firmer drape | usually opaque | premium bedding, duvet covers |
| 30 | 130.2 | heavy, stiff, upholstery-like | usually opaque | curtains, heavy furnishing fabric |
Hand, opacity and drape are typical values for the weaves usual in each use; weave and finishing shift all three. Values are calculated from the 4.34 g/m² conversion and given to one decimal place. Where you see them rounded to whole numbers elsewhere, 22 momme is quoted as about 95 g/m² and 25 momme as about 109 g/m².
Where the 4.34 figure comes from
The conversion is worth showing rather than asserting, because a second figure circulates and the two do not agree.
The definition fixes an area: 100 yards by 45 inches. In metric that is 91.44 m × 1.143 m, or 104.516 m². One momme is one pound spread over that area, and a pound is 453.592 g. Dividing gives 453.592 ÷ 104.516 = 4.3399 g/m², which is where the 4.34 rule of thumb comes from.
You will also find 4.3056 g/m² quoted, and it is close enough that the difference rarely shows. It comes from rounding the pound to 450 g before dividing (450 ÷ 104.516 = 4.3056). At 22 momme the two constants differ by less than one gram per square metre, so either will do for judging a product. For a stated figure, 4.34 is the one that follows from the definition.
Why weight instead of thread count?
For cotton bedding, thread count, the number of threads per square inch, is the usual quality figure. Silk settled on weight instead, and for a good reason: silk threads are so fine that a raw thread count tells you little. Fabric weight reflects thread fineness and weave density together, without separating them. Momme and grade then describe two different things: momme is about the fabric, while the raw-silk grade, such as 6A, is a multi-factor grading of the raw silk. We cover what lies behind that grading in our guide to mulberry silk.
Which momme for what?
Where the table above gives the measured weight of each value, this one groups them the way the trade talks about them. There is no official standard, but there is a settled trade convention you can use as a guide:
| Momme | Character | Typical use |
|---|---|---|
| under 16 | light, fluid, sometimes sheer | scarves, linings |
| 16 to 19 | light to medium weight | blouses, light bedding |
| 19 to 25 | dense and opaque, substantial in the hand | pillowcases, bedding, bonnet linings |
| over 25 | heavy and very dense | heavy bedding, curtains |
For silk pillowcases, 19 to 25 momme is the usual quality range. Within it, 22 momme has become the established standard: heavy enough to be opaque in the usual weaves and feel dense in the hand, while staying soft and flowing rather than stiff.
Why pillowcases stop at around 22 to 25 momme
Silk is woven far heavier than 25 momme, so the ceiling on a pillowcase is a choice rather than a limit of the material. Three things set it.
Material input rises with the weight. As the momme figure rises, so does the amount of silk per square metre, and with it the material input. Going from 22 to 30 momme adds around a third more silk per square metre, and that shows up in the shelf price, while the extra weight is felt mainly as warmth and a firmer drape rather than as more of what silk is on a pillow for.
Weight starts to work against the purpose. A pillowcase has to move with your head and settle back flat. In the satin and plain weaves used for bedding, a 30 momme fabric behaves more like a furnishing textile: it holds its shape, creases differently, and its surface becomes noticeably firmer.
Breathability drops as the weave tightens. The denser the fabric, the less air moves through it. In bedding fabrics the extra weight above roughly 25 momme is therefore felt mainly as warmth, which is how the buying guides describe it too.
The result is a practical band rather than a single right answer: by the trade convention 19 momme is the sensible entry point, 22 is where most quality pillowcases sit, and 25 is generally taken as the upper limit that still behaves like bedding.
Is more momme always better?
No, and this point often gets lost in the marketing. The momme figure describes the fabric, not the quality of the fibre. A high-momme fabric woven from low-grade silk is still a low-grade product. A very high momme also has practical downsides: the fabric gets heavier, warmer, and noticeably more expensive, while what the extra weight adds is mainly warmth and a firmer drape.
Momme only means something read alongside the rest: the fibre (mulberry silk), the raw-silk grade (6A is the top grade of the multi-factor raw-silk grading, which weighs evenness, cleanliness and strength among other things), and the weave (usually a satin weave). If a silk product states no momme at all, that is not automatically a bad sign, but it is worth asking about.
What the momme figure does not tell you
A single number cannot carry a whole product, and it is worth being precise about where its reach ends.
It says nothing about the fibre. Momme measures the fabric only. Two pillowcases at 22 momme can be woven from very different silk, which is why the fibre statement and the raw-silk grade belong next to it.
It does not describe the make. Seams, closure and finishing are judged separately. German buying guides routinely rate the closure type on its own, comparing an envelope closure against a hidden zip, and that has nothing to do with fabric weight.
It is not a wash-life figure. Buying guides often state that heavier silk is more hard-wearing, and the usual explanation is mechanical: the same rubbing is spread across more fibre per square metre. What that does not support is a prediction of how long a given pillowcase lasts. Silk is a protein fibre and stays sensitive to heat, alkaline detergent and mechanical stress at every weight, so how it is washed matters more than where it sits on the momme scale. Care guidance in the trade converges on cool water and a detergent made for silk or wool, with the temperature on the care label as the ceiling. Our own guide to washing silk covers the method.
It does not settle the weave. Momme and weave are independent: a satin weave and a plain weave at the same momme feel quite different, because the surface, not the weight, is what your skin registers.
How to check the momme figure on a product page
Four things make the number readable, and they take about a minute.
- Find the figure at all. Look for a number followed by “momme” or “mm” in the specifications, not only in the headline. If a silk product states no momme at all, that is not automatically a bad sign, but it is worth asking about.
- Check it against the fibre statement. A momme figure means most when it sits beside “100% silk”, ideally mulberry silk. A high momme on an unnamed fibre, or on a blend, describes a fabric you have not been told the composition of.
- Read “mm” carefully. On silk, mm is the abbreviation for momme. A pillowcase listed as “22mm” is 22 momme, not 22 millimetres.
- Sanity-check the weight if it is given. Where a page states grams per square metre as well, the two should agree: divide the g/m² figure by 4.34 and you should land back on the stated momme. A 22 momme product should read close to 95 g/m².
Momme at RENESSY
The pillowcases in our silk pillowcase collection sit at 22 momme: 100% organic mulberry silk, Grade 6A, woven with silk on both faces instead of a silk front over a cotton or synthetic backing. The pillowcases are GOTS certified for the organic fibre and carry the OEKO-TEX MADE IN GREEN label. Dermatest has tested and certified them for skin compatibility, including sensitive skin. Keeping silk at its best is covered in our guide on how to wash silk.
Frequently asked questions
How much does 22 momme silk weigh?
About 95 grams per square metre, following the rule of thumb that 1 momme is roughly 4.34 g/m². For comparison: 19 momme is about 82 g/m², and 25 momme about 109 g/m².
How do I convert momme to g/m² myself?
Multiply the momme figure by 4.34. The constant comes from the definition of the unit: one pound (453.592 g) spread over 100 yards by 45 inches (104.516 m²).
Where does the momme unit come from?
From Japan, where momme (匁) is a traditional unit of weight. Through the historic silk trade it became the international measure for silk fabric, and it is still used worldwide today.
Is momme enough to judge quality?
No. It is an important piece, but it says nothing about the quality of the fibre. Alongside it, check the fibre statement (“100% silk”, ideally mulberry silk), the raw-silk grade, and any certifications.
What momme should a silk pillowcase be?
19 to 25 momme is the range buying guides settle on, with 22 momme the most common choice. Below 19 the fabric is generally considered thin for a pillowcase; in bedding weaves, above 25 it starts behaving like furnishing fabric.