What Is Sizing Like at COS Clothing?

COS sizing is true to the size on the label, but the cut runs generous and architectural – which is exactly why so many shoppers swear it “comes up big.” In reality, the number on the tag is accurate; it’s the deliberately relaxed, slightly oversized silhouette COS has built its name on that throws people off. Once you understand that one thing, the fit becomes very easy to predict.

I’ve been styling clients in COS for years, and it’s one of those brands I reach for constantly because the quality-to-price ratio is genuinely excellent. But I’ve also watched plenty of people order their “usual” size, feel swamped, and decide the brand isn’t for them. It almost always is – you just have to read it correctly.

The short answer

COS uses both letter sizing (XS–XL) and numeric sizing (4–18), and both run true to UK high-street standards.
The cut is intentionally loose, boxy and elongated – Scandi-minimalist by design.
For a closer fit, size down one. For the intended relaxed look, stick to your normal size.

How COS actually fits, piece by piece

Tops and knitwear

This is where COS runs most generous. Jumpers, shirts and tees are cut with real volume through the body and dropped shoulders. If you like a neat fit, size down. If you love that effortless tucked-and-bloused look, stay true to size.

Trousers

COS trousers are cut long. They’re designed with a tall, leggy line in mind, so if you’re petite, factor in a hem. The waist is usually accurate, but the leg is roomy and the high-rise styles sit beautifully.

Dresses

Often the trickiest category. COS dresses can be voluminous, so the shape matters far more than the number. Belted and wrap styles are much more forgiving than the column shifts – choose by silhouette, not size.

Coats and outerwear

Built for layering, so there’s plenty of room already. I rarely size up here, even with a chunky knit underneath.

A win and a fail from my own wardrobe

My favourite COS win: a charcoal wool wrap coat I bought in my true size that’s been in heavy rotation for four winters – proof their outerwear sizing is reliable and the cost-per-wear is unbeatable. My fail? An oversized poplin shirt dress I ordered in my “safe” larger size for a wedding. I looked like I was wearing a very chic tent. I exchanged it for one size down and it was perfect. The lesson stuck: with COS, trust the cut, not your nerves.

If COS isn’t quite your fit, try these

Not everyone gets on with COS’s relaxed lines, and that’s completely fine. Here’s where I send clients who want a similar minimalist aesthetic but a different fit profile.

High street

Uniqlo – Japanese minimalism with reliable, consistent sizing; the closest true-to-size alternative to COS basics.
Massimo Dutti – A more tailored, elevated cut than COS; ideal if you find COS too boxy.
Whistles – Contemporary British label with a precise, true-to-size fit and clean lines.
Jigsaw – Understated quality with a slightly more structured shape than COS.
Mango – Sleek and on-trend, but runs a touch small, so size up where COS would have you size down.
Reiss – Sharp tailoring and a slimmer fit for anyone wanting definition over volume.
M&S – Brilliant for dependable, well-sized wardrobe staples at a gentle price.

Premium

Totême – The natural step up from COS: Scandinavian minimalism, also cut relaxed, with beautiful fabrics.
Joseph – Refined, fluid tailoring with an elegant, slightly more fitted silhouette.

Luxury / designer

Max Mara – The gold standard for minimalist coats and camel tailoring; impeccable, true-to-size construction.

Two independents worth knowing

The Frankie Shop – A cult New York label built on oversized, sculptural minimalism; if you love COS’s volume, you’ll adore this.
Ninety Percent – A British sustainable brand with clean, modern lines and an honest, true-to-size fit.

Never guess your COS size again

Tellar.co.uk is the UK’s leading sizing tool – match your body to over 1,500 brands instantly, so you never squint at a size guide again.

Measure once using your bust, waist and hip – or simply enter a brand size you already own.
Use the Store Size Lookup to get your exact size in any brand – COS, Reiss, Everlane, Arket and more.
Always free, no downloads needed – it works straight in your browser.

Beyond the tool, there’s the Tellar Fashion Hub – a library stacked with free posts from our stylists. Honest, unbiased, independent and always free. Real style advice, top picks and the best brands, with no sponsored fluff.