Silk Fabric Weight: How Light, Medium and Heavy Divide

Silk weight is measured in momme (mm), a unit the trade has used for a century. Converted, one momme is about 4.34 g/m², so the two systems line up: a 12 mm is roughly 52 g/m², a 19 mm roughly 82, a 30 mm roughly 130. Those three numbers are also the honest boundary between what most people call light, medium and heavy silk.

Light silk — under ~60 g/m² (6–12 mm)

Medium silk — ~60–100 g/m² (14–22 mm)

Heavy silk — over ~100 g/m² (25–40 mm)

So which band should you be in?

The question behind the weight question is nearly always one of three things. If it is drape — how the cloth falls under its own weight — the answer is almost always medium, 14–22 mm. If it is opacity, medium does it; light will not without a lining. If it is structure — a bodice that stands, a coat that hangs — that is heavy, 25 mm and up, and the families change with it: you leave charmeuse behind and arrive at mikado and duchess.

What about stretch silk?

Silk fibre itself does not stretch the way knitted yarn does. Woven silk gives slightly on the bias and in a crepe twist, but if a pattern genuinely needs two-way stretch, that cloth is woven with elastane or knitted — and it is a different fabric from anything on our card. We would rather say that plainly than sell a crepe as a stretch silk.

Frequently asked questions

What is a lightweight silk?

In practice, anything under about 60 g/m² — roughly 12 momme and below. Chiffon, gauze, organza and lining-weight habotai live here.

What is a heavyweight silk?

Above roughly 100 g/m², from about 25 momme up. Mikado, duchess satin and heavy noil are the usual families; 30–40 mm behaves like a light wool.

Does silk fabric stretch?

Woven silk has very little mechanical stretch — the give you feel is the weave, not the fibre. Real stretch comes from adding elastane or from a crepe twist yarn, and those are different constructions, not a heavier plain charmeuse.

What does GSM mean next to momme?

Momme is the silk trade's own unit; GSM is grams per square metre and the wider textile world's. One momme is about 4.34 g/m², so a 19 mm is roughly 82 g/m².