What Is Sizing Like at COS menswear?

COS is cut clean, straight and generous, and it leans slightly larger than most of the high street. It's a Scandinavian-minded brand (part of the same group as Arket and Weekday), and that shows in the design language — architectural lines, dropped shoulders, plenty of intentional volume. The clothes are designed to skim the body rather than hug it.

The catch for us blokes is that the fit isn't uniform across the range. A relaxed tee and a tailored blazer are cut to two completely different briefs, so "my COS size" isn't really one number. Here's how it shakes out:

Tees and casual tops

Run relaxed to oversized. COS builds most of its jersey with a loose, boxy body and a dropped shoulder on purpose.
If you like a cleaner, closer fit, size down — a lot of blokes take a small where they'd normally reach for a medium.
Watch the shoulder seam: on the boxier styles it should sit slightly off the shoulder by design, not halfway down your arm.

Shirts

The Regular fit is true-to-size but roomy through the body — comfortable, but not tapered.
Chest is usually the deciding factor. If you're broad, that's your limiting measurement even on a relaxed cut, so buy for the chest and have the body taken in if you want it neater.
The oversized poplin styles are genuinely oversized — lovely worn open over a tee, less so if you wanted a smart everyday shirt.

Tailoring and blazers

This is where COS is closest to true-to-size. The structured pieces fit much more predictably than the jersey.
Expect a modern, streamlined shape with a slightly relaxed shoulder — not a sharp Italian cut, more an easy, unstructured one.
Take your normal jacket size and try before you commit if you can.

Trousers

The tailored, non-stretch trousers come up true to size at the waist — trust the waist measurement over the alpha label.
COS cuts a straighter leg than the curvier high-street brands, so if you're used to a slim taper, the leg line will read looser.
The wide and relaxed styles are exactly that. Size down only if you specifically want them neater.

Knitwear and outerwear

Both run large and long. Coats in particular are cut with a generous, cocooning line, often with a dropped shoulder.
Size down one if you want a trimmer silhouette — but leave a touch of room if you're a heavy layerer, because that's the point of the cut.
Shorter blokes should check the length carefully; COS coats can sit long, and a hem that hits below the knee changes the whole proportion.

My Honest Advice on Buying COS

After years of dressing clients in it, here's how I'd approach a COS order:

Decide on the silhouette first. COS is a brand where you choose whether you want relaxed or fitted, then size to that intention — not the other way round.
Buy for your biggest measurement. For most men that's the chest or the shoulders. A tailor can bring a body in far more easily than they can let a chest out.
Don't trust the alpha label alone. A COS medium is not an M&S medium. Check the actual centimetre measurements on the product page every time.
Lean into what it does well. COS is at its best for elevated minimalism — clean knits, easy trousers, unfussy outerwear in quiet colours. That's the wardrobe it was built for.

Brands to Wear Alongside COS

If you love the clean, considered COS look, these are the brands I'd genuinely send a client to — across every budget. All of them share that pared-back sensibility, so they layer together beautifully.

On the high street

Massimo Dutti — the natural step up in high-street tailoring. Where COS goes architectural, Massimo Dutti goes softly Mediterranean: gorgeous knitwear, smart chinos and blazers that fit a shade neater than COS if you want more shape.
Weekday — COS's Scandi cousin (same group), and the place to go for the wider-leg denim and boxy basics that define the current relaxed look, usually for a good deal less money.

Independent and boutique

Asket — a Swedish brand built entirely around a permanent collection of perfect essentials, with proper mid-length sizing (S/M/L split into shorter and longer bodies). If COS's inconsistency drives you mad, Asket is the antidote.
Norse Projects — Danish, minimal and quietly brilliant. Their overshirts, knits and relaxed trousers are the sweet spot between COS's price point and true designer money, with far more predictable fit.

Designer and luxury

Margaret Howell — the understated end of British luxury. Beautiful cloth, unshowy cuts and a fit philosophy that's essentially COS grown up. The pieces last decades.
Lemaire — the French label that arguably invented the relaxed-volume look COS borrows from. Dropped shoulders and soft tailoring done at the very highest level.
Jil Sander — if minimalism is your religion, this is the cathedral. Precise, architectural, impeccably made. The aspirational upgrade for anyone who's maxed out their COS wardrobe.

Never Guess Your COS Size Again

COS is exactly the kind of brand where guesswork costs you — a returns slip, a wasted lunch break, or a jumper you never quite wear. That's the problem Tellar was built to solve.

Tellar is the UK's leading sizing tool: measure yourself just once — chest, waist, hip, or simply enter your size in a brand you already know fits — and Tellar matches your body to 1,500+ brands instantly. No more scrolling size guides, no more ordering two sizes to be safe.

Measure once and you're set for life.
Store Size Lookup gives your precise size in COS, Reiss, Everlane, Arket and hundreds more.
Shop with confidence — fewer returns, better-fitting kit.
Always free, works straight in your browser, nothing to download.

There's also the Tellar Fashion Hub — a free library of honest, unbiased, independent posts from our stylists covering every fashion question you can think of. Style advice, top picks, best brands. No adverts, no sponsors, no catch.

Find Your COS Size → How to Measure →

Get your measurements dialled in and COS goes from a gamble to one of the smartest brands on the high street. Buy for the silhouette you actually want, trust the centimetres over the label, and you'll wonder why you ever found it confusing.

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Tellar is always honest, unbiased and unsponsored. We never take payment to recommend a brand — every pick here is based on genuine stylist experience.