What Is Momme in Silk, and What Weight Is Best?

Momme is the weight of silk — the number that tells you how much actual silk is packed into the cloth, and so how dense, durable and substantial it will feel. The higher the momme, the more silk per square metre. For a pillowcase, the sweet spot is 22 momme: heavy enough to glide, drape and last for years, without tipping into something warm or stiff.

It's the single most useful number on a silk label, and the one most often left off. Here's how to read it.

So what is momme, exactly?

Momme (pronounced "mommy", and written 匁) is an old Japanese unit of weight, and in silk it measures how much the fabric weighs for a set size — specifically, the weight in pounds of a piece 45 inches wide and 100 yards long. One momme works out to about 4.34 grams per square metre. You don't need the arithmetic; you need the idea. Momme is to silk what thread count is to cotton: a shorthand for density. A 22-momme silk simply has more silk woven into the same space than a 16-momme one, which is why it feels weightier in the hand and lasts longer on the bed.

Does a higher momme always mean better silk?

Up to a point, yes — but only up to a point. A higher momme does mean a denser weave: more durable, more opaque, with a richer drape and a longer life. That's why bargain-bin silk is almost always low momme — it's using less silk. But heavier isn't endlessly better; it's about the right weight for the job. Very high momme silks (28, 30 and up) are wonderful for heavy bedding or upholstery, yet against your face they can feel warm and a touch stiff. The aim isn't the biggest number — it's the number suited to the purpose.

What momme is best for a silk pillowcase?

For pillowcases, the considered range is 19 to 25 momme, and 22 is widely regarded as the sweet spot. At 22 momme the silk is dense enough to feel genuinely substantial, to glide rather than catch, and to survive years of washing without thinning or fraying — but light and breathable enough to stay cool against your skin all night. Below 19 momme, silk becomes the featherweight stuff of scarves and light blouses: lovely to wear, too flimsy to last as bedding. Push much past 25 and you gain heft you don't need and warmth you may not want. Twenty-two is the Goldilocks weight.

What does "22 momme" actually mean — and is it good?

It means the silk weighs 22 momme for that standard size, and yes — for a pillowcase it's about as good as it sensibly gets. Think of it as the point where durability and comfort meet: substantial enough that the pillowcase keeps its body and sheen for years, fine enough that it still feels cool and liquid-smooth under your cheek. When a brand states 22 momme plainly, it's usually a sign they've nothing to hide about how much silk you're actually getting.

Momme or grade — which tells you the quality?

Both, and they're not the same thing. Momme measures the weight of the woven fabric; a grade (you'll see "6A" used for the top tier) describes the quality of the raw fibre — its length, uniformity and colour before weaving. A silk can be a high grade but woven thin, or heavy momme from mediocre fibre. The reassuring combination to look for is a high grade of mulberry silk woven to 22 momme — fine fibre, generous weight. One without the other only tells half the story.

How do you use momme when buying silk?

Read for three things together: the momme, the fibre, and the certification. You want a stated momme weight (22 for a pillowcase), the words "100% mulberry silk" rather than a vague "silk" or, worse, "satin" — which is a weave often made of polyester — and ideally an OEKO-TEX certification that the fabric has been tested for harmful substances. If a silk product doesn't mention its momme at all, treat the silence as an answer: quality silk tends to be proud of its weight.

Ours is no secret: every LS Silk AU pillowcase is 22-momme, 100% mulberry silk, OEKO-TEX certified.

It's a strange little word to fall for, momme — a unit of weight borrowed from another century, doing the quiet work of telling you whether a silk will still be smooth in five years or pilled in five months. Learn to look for it, and you'll never again pay good money for silk that was mostly air.