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How to Choose Suit Fabric Weight: Grams, Super Numbers, and Seasons
Year-round cloth is about 270–310 g. Tropical sits 240–270 g. Flannel starts near 320 g. Super numbers are fineness, not quality, and high Supers shine.
Updated 27 Aug 2026 · 6 min read · how to choose suit fabric weight
Grams per metre is the number that matters
Mills quote grams per linear metre at a standard width, or ounces per square yard. They are not identical units, but in shop talk 250 g is light, 280–300 g is mid, 350 g is heavy. Ask. A salesman who only says “four-season Super 150s” is selling a label. Midweight worsted in navy or charcoal is the first-suit cloth in the first-suit brief. You can feel midweight: it drapes, it does not float, it does not sit like a blanket on the arm.
High twist and open weaves (fresco) wear cooler than a closed worsted at the same gram weight. That is the next distinction: tropical wool versus fresco.
Super numbers, shine, and the marketing trap
Super 100s–120s: a working worsted, durable, matte enough. Super 130s–150s: finer, softer, more wrinkle-prone, more shine at the seat and thighs after a year of sitting. Super 180s and the costume numbers above: dinner-party cloth, not a commute. Fineness is fibre diameter, not canvas quality and not a better shoulder. A fused Super 150s at $400 is still fused.
| Weight (approx.) | Season | Use |
|---|---|---|
| 230–260 g tropical / fresco | Hot weather, hard air-con contrast | Summer suit, not your only suit |
| 270–310 g worsted | Three to four seasons | First suit, office rotation |
| 320–380 g worsted or flannel | Cold months | Winter suit, odd trousers |
| 400 g+ heavy flannel | Proper winter | A second or third cloth |
Climate, office air-con, and the one-suit man
If you live in a hot city and sit in 22 °C air-con, midweight still wins as the only suit: tropical will look frail under a 9–11 mm watch and a winter overcoat. If you already own midweight, add fresco or tropical for outdoor summer weddings, and flannel for December. Travel: midweight plus a 36–40 mm thin watch under the cuff beats a 240 g suit that wrinkles into a map by the time you land. Hang the jacket; do not crush 280 g canvas in a tiny garment bag for 12 hours without a fold.
Questions, answered
- Is a heavier suit always better quality?
- No. Weight is climate. Canvas, wool content, and the mill matter more. A 400 g fused polyester-blend is still a bad suit.
- Can I wear 300 g wool in August?
- Indoors, often yes. Outdoors in 32 °C sun, you will feel it. That is when tropical or fresco earns a second jacket.
- What does 9 oz versus 11 oz mean on British labels?
- Ounces per square yard, roughly. 9 oz is lighter (tropical-to-mid), 11–13 oz is mid to heavy. Ask for grams if the tag is silent.
