What Is Momme? Silk Weight, Explained

Momme is the number that does the real work on a silk pillowcase listing — once you know what it measures, two cases that look identical in photos become easy to separate.

On this page

The definition
What the numbers mean on a pillowcase
Momme is not thread count — and grade is a third thing
How to use momme when comparing

The definition

Momme (pronounced 'mommy', written mm) is a unit of weight for silk fabric: it is the weight, in pounds, of a piece of silk 45 inches wide and 100 yards long. A 19 momme fabric weighs 19 pounds at that standard size; a 25 momme fabric weighs 25. Higher momme simply means more silk packed into the same area — a denser, heavier fabric.

What the numbers mean on a pillowcase

Pillowcases are commonly sold somewhere between the mid-teens and 30 momme. At the lighter end the fabric is thinner and usually cheaper; it drapes softly but wears faster. Through the low-to-mid twenties, cases feel noticeably more substantial. At the top end you get the densest, most hard-wearing fabric — and the highest prices.

There is no single 'best' momme. It is a trade-off between weight, durability and price, and it only compares silk against silk: a satin polyester case has no momme at all, whatever its listing implies.

Momme is not thread count — and grade is a third thing

Thread count is a cotton measure (threads per square inch) and doesn't transfer to silk, which is why silk listings use momme instead. If a silk listing leads with a big thread-count number, treat it as marketing rather than a spec.

Silk grade is separate again: it describes the quality and length of the raw silk fibres, graded from A down, with 6A the top grade. A listing can pair a high momme with an unstated grade, or a top grade with a light momme — the two numbers measure different things, and both appear in our spec tables when the listing states them.

How to use momme when comparing

Use momme as a density check alongside the things you can feel in use: the closure (zip or envelope), the size, and whether the case is sold singly or as a pair. Two 22 momme cases can still differ in all three. Our mulberry silk collection shows each product's momme in its spec table wherever the listing states it.