Somewhere on the label of a decent suit there is a number: Super 110s, Super 130s, sometimes Super 150s. Salesmen say it in a tone implying that higher is better, men nod, and almost nobody knows what it means.
Here is the short answer, which will save you money: the number measures fineness, not quality, and for most men a higher number is worse.
And that is only one of several things worth knowing about wool. It is the most useful fibre in menswear — it insulates when damp, resists odour, breathes, holds a crease, and returns to shape — but the word covers an enormous range of cloths behaving in completely different ways.
Super numbers, decoded
The Super number measures the diameter of the wool fibre, in microns. Higher numbers mean finer fibres.
| Super number | Fibre diameter | Feel | Durability | Best for |
|---|---|---|---|---|
| Super 100s | 18.5 microns | Sturdy, slight texture | Excellent | Daily wear, travel |
| Super 110s–120s | 17.5–18 microns | Smooth, still robust | Very good | The sweet spot |
| Super 130s | 17 microns | Noticeably soft | Good | Office, occasional wear |
| Super 150s | 16 microns | Very soft, lustrous | Poor | Special occasions |
| Super 180s+ | 15 microns or less | Extraordinarily soft | Very poor | Display, essentially |
Finer fibres are weaker fibres. A Super 150s suit feels wonderful in the shop and creases if you look at it, wears shiny at the elbows and seat within a year or two of regular use, and is expensive to replace.
For a suit you will actually wear, Super 110s to 130s is the correct range. Below 100s can feel coarse; above 150s is a suit for a wedding you attend once. This is the same buy-once logic that runs through what is worth buying once.
One more caveat: the Super number tells you nothing about the construction of the garment — the canvas, the stitching, the finishing. A Super 130s suit with a glued fused front is worse than a Super 110s with a floating canvas.
The wool cloths
Worsted
The default suiting cloth. Worsted wool is made from long fibres combed parallel before spinning, producing a smooth, tightly woven, hardwearing cloth that holds a crease.
It is what most suits are made from, and it is the right answer for business. Smooth, formal, and it presses beautifully.
Flannel
Wool that has been brushed after weaving, raising a soft fuzzy nap. Warmer than worsted, considerably softer, and with a matte finish that reads as relaxed rather than corporate.
Grey flannel trousers are one of the great menswear staples — they go with everything from a blazer to a jumper. A flannel suit in autumn is warmer and more characterful than worsted, though it wrinkles more and shines at stress points if worn hard.
Tweed
Coarse, thick, textured wool from Scotland and Ireland, typically with flecks of multiple colours. Heavy, extremely warm, effectively weatherproof and enormously durable.
Tweed is country cloth — it belongs with odd jackets, boots and knitwear, and it looks slightly odd in a city boardroom. Herringbone and Donegal are the two patterns most worth knowing.
Fresco
An open-weave, high-twist worsted, developed for hot weather. Hold it up and you can see through it. It is the best summer suiting there is — nearly as cool as linen but wrinkle-resistant and properly formal. The full case for it is in the summer suiting guide.
Hopsack
A loose basket weave with a visible texture. Breathable, wrinkle-resistant, and the classic cloth for a navy blazer. Slightly less formal than worsted because of the texture, which is exactly why it suits an odd jacket — see the blazer guide.
Merino
Fine wool from Merino sheep, used mostly in knitwear and base layers rather than tailoring. It is the best fibre for jumpers and thermal layers for the reasons set out in the knitwear guide.
Weight, and why it matters more than the Super number
Cloth weight is given in grams per metre, and it does more to determine when you can wear a suit than any other specification.
| Weight | Season | Character |
|---|---|---|
| Under 240g | High summer | Light, drapes softly, creases easily |
| 250–280g | Spring / summer | The lightweight standard |
| 280–320g | Year round | The most versatile weight to own |
| 320–380g | Autumn / winter | Holds shape beautifully, drapes well |
| Over 400g | Deep winter, overcoats | Heavy, structured, very warm |
Heavier cloth actually looks better. It drapes rather than clinging, resists wrinkles, and holds a press. The fashion for very lightweight suits produced a generation of tailoring that wrinkles by lunchtime.
If you own one suit, make it around 300g. It will work for roughly nine months of the year.
Reading a suit label properly
In order of how much each tells you:
- Fibre content. 100% wool. Any significant polyester is a red flag — see the polyester piece for why.
- Weight in grams. Determines the season. More useful than anything else on the label.
- Construction. Full canvas > half canvas > fused. This matters more than the cloth.
- Super number. Useful within reason. 110s–130s for daily wear.
- Mill name. Loro Piana, Vitale Barberis Canonico, Fox Brothers, Holland & Sherry indicate a serious cloth.
The canvas test: pinch the front of the jacket between the buttonhole and the lining and rub your fingers together. If you can feel a distinct third layer floating between the outer cloth and the lining, it is canvassed. If it feels like two layers glued together, it is fused — and fused jackets bubble and delaminate over time.
Wool myths worth discarding
- “Higher Super number means better quality.” It means finer and more fragile. 150s is not an upgrade on 120s for daily wear; it is a downgrade in durability.
- “Wool is itchy.” Coarse wool is itchy. Merino and fine worsted are not — the itch comes from fibre diameter, not from wool as such.
- “Wool is only for winter.” Fresco and tropical worsted are among the best hot-weather cloths available.
- “Wool needs frequent dry cleaning.” The opposite. Wool is naturally antibacterial and self-cleaning to a degree; frequent dry cleaning shortens its life. Brush and air instead — the method is in the suit cleaning guide.
Caring for wool
- Rest it 24 hours between wears. Wool recovers its shape as it dries out. Wearing the same suit daily roughly halves its life.
- Brush after each wear with a natural bristle brush, downward. This removes the dust and grit that cut fibres.
- Use a broad wooden hanger. Wire hangers deform shoulders permanently.
- Steam rather than iron where possible — direct heat flattens the nap and creates shine. See the wrinkle guide.
- Dry clean two or three times a year at most.
- Store clean in summer. Moths eat body oils and skin cells, not clean wool.
Frequently asked questions
What does Super 120s mean on a suit?
It measures the fineness of the wool fibre — Super 120s is roughly 17.5 to 18 microns in diameter. Higher numbers mean finer, softer fibres. It is a measure of fineness rather than quality, and finer fibres are also weaker and less durable.
Is a higher Super number better?
Not for a suit you wear regularly. Finer fibres are more delicate, crease more easily and develop shine at the elbows and seat faster. Super 110s to 130s is the practical range for daily wear. Above 150s is best reserved for occasion wear.
What weight wool suit should I buy?
Around 300 grams per metre if you are buying one suit — it works for roughly nine months of the year. Under 250g is summer-only and creases readily; over 380g is genuinely wintry. Heavier cloth drapes better and resists wrinkles more effectively than lightweight cloth.
What is the difference between worsted and flannel?
Worsted is made from long fibres combed parallel before spinning, producing a smooth, tightly woven cloth that holds a crease and reads as formal. Flannel is brushed after weaving to raise a soft nap, making it warmer, softer, matte in finish and more relaxed in character.
How can you tell if a suit jacket is canvassed or fused?
Pinch the jacket front between the buttonhole and the lining and rub your fingers. If you feel a distinct third layer floating between the outer cloth and lining, it is canvassed. If it feels like two layers bonded together, it is fused. Fused jackets can bubble and delaminate over time.
Does wool need frequent dry cleaning?
No — the opposite. Wool is naturally antibacterial and resists odour well, and dry cleaning chemicals are harsh on the fibre. Brush the garment after each wear, air it, and spot-clean marks. Two or three dry cleans a year is plenty for a regularly worn suit.
The short version
- Super numbers measure fineness, not quality. 110s–130s for real life.
- Weight matters more. ~300g is the most useful year-round suit.
- Construction beats cloth. Canvassed over fused, always.
- Worsted for business, flannel for autumn, tweed for the country, fresco for summer.
- Heavier cloth drapes better and wrinkles less.
- Brush and rest your wool. Dry clean rarely.
Ignore the salesman pointing at the Super number. Look at the weight, feel for the canvas, and buy the cloth that suits the season you will wear it in.
Read next
