If you source silk, you will eventually face this question: a supplier quotes a price, and when you ask "what weight is it?" they say "19 momme." You wonder – how many grams per square metre is 19 momme? How do these two units convert? And does a higher momme always mean better quality?
If you've ever had these questions, this article is for you.
What Is Momme?
Momme (mm) is a unit of weight used almost exclusively for silk. It originates from the Japanese word monme (匁), a traditional Japanese weight unit later adopted by the international silk trade to measure fabric thickness.
1 momme = 4.34 grams per square metre (g/m²).
That means a 19 momme silk fabric weighs 19 × 4.34 = 82.46 g/m². Common momme weights for charmeuse are 12, 16, 19, 25, 30, and 40. Higher momme means a thicker, heavier fabric – and generally higher cost.
What Is GSM?
GSM (grams per square metre) is the universal fabric weight unit used across the textile industry – for cotton, linen, wool, synthetics, and everything in between. It simply measures how many grams one square metre of fabric weighs.
To measure GSM, you cut a fixed area (usually 10cm × 10cm), weigh it on a precision balance, and extrapolate to grams per square metre.
How to Convert Between Momme and GSM
The formula is simple:
GSM = momme × 4.34
And the reverse:
momme = GSM ÷ 4.34
Here are some common values:
| Momme | GSM (g/m²) |
|---|---|
| 16 mm | 69.44 |
| 19 mm | 82.46 |
| 25 mm | 108.50 |
| 30 mm | 130.20 |
| 40 mm | 173.60 |
Why Are There Two Different Units?
Momme is a historical industry convention. Japan, as one of the birthplaces of modern silk manufacturing, brought the traditional weight unit monme into silk trading. The International Silk Association (ISA) still recognises momme as the standard unit for silk, and it remains widely used globally.
GSM is the modern international standard used across all textile types – regardless of fibre. In sourcing, you will encounter three scenarios:
- Suppliers who use momme: typically silk specialists, especially in high-end silk.
- Suppliers who use GSM: usually mills that handle multiple fibres (cotton, linen, synthetics).
- Suppliers who provide both: the most professional ones will give you both measurements.
Common Misconceptions
Myth 1: Higher momme is always better.
Not necessarily. 19mm charmeuse is great for shirts and dresses; 25mm is better for outerwear; 30mm+ is suited for heavy coats or formalwear. The right weight depends on your design, not on a simple “higher is better” rule.
Myth 2: Same momme means same hand feel.
Wrong. Two fabrics both labelled 19mm can feel completely different depending on yarn quality, weaving density, and finishing. Momme is a weight unit, not a quality grade.
Myth 3: Whatever the supplier says is correct.
You can verify. Request a test report from the supplier, or measure it yourself – cut a 10cm×10cm sample, weigh it, multiply by 100 to get GSM, then divide by 4.34 to get momme.
Always ask your supplier to specify the unit. If they say "19" – confirm whether they mean 19 momme or 19 g/m². The difference is more than fourfold.
Practical Advice for Buyers
- Clarify the unit at order stage. Never assume. Confirm whether the quoted weight is in momme or GSM – they are not interchangeable.
- Request test reports. Reputable mills will have weight test data for every batch. Ask for third-party or in-house test results.
- Verify upon receipt. After delivery, cut a sample and weigh it to confirm the weight matches the contract. A tolerance of ±5% is generally acceptable.
- Don't fixate only on momme. Weight is just one factor. The final hand feel, luster, and drape also depend on fibre grade, weave density, and finishing.
Understanding momme and GSM is one of the most fundamental skills in silk sourcing. The next time a supplier says "19 momme," you will immediately know it's 82.46 g/m² – and whether that thickness is right for your product.
Frequently Asked Questions
I find. I check. I seal. You relax.