The Top 10 Clothing Brands That Run Large

The ten women's brands that consistently run large are COS, Marks & Spencer, Boden, Seasalt Cornwall, Gap, Fat Face, Toast, Ralph Lauren, Max Mara and Ganni. In most of these, a UK 12 will feel closer to a 14, and in the boxier pieces you'll often be better off dropping a full size. It happens for two reasons: some houses cut deliberately loose and oversized as a design signature, and others quietly add a couple of centimetres across the bust and waist because generous sizing keeps customers happy. Knowing which is which is the difference between looking relaxed and looking like you've borrowed something.

The brands that run large, and by how much

COS — the biggest offender, and unapologetically so. Shirts, blazers and knitwear are cut with deep armholes and dropped shoulders. Size down one, sometimes two in outerwear. The trousers are the exception and sit far closer to true.
Marks & Spencer — generous across almost every line, particularly jersey, trousers and the Autograph knitwear. Most people I dress take a size smaller here than they do at Zara.
Boden — roomy through the waist and hip, especially in the printed dresses and cotton knits. Lovely fabrics, but size down if you want any shape at the waist.
Seasalt Cornwall — designed for layering over a jumper in coastal weather, so the fit is soft and easy by design. Their dresses and smocks run particularly large.
Gap — American vanity sizing at its most obvious. Denim is the worst culprit and will stretch further after an hour's wear.
Fat Face — casual, relaxed and forgiving. Jersey dresses and sweatshirts run a full size big.
Toast — intentionally oversized. Volume is the whole point, but that means an XS often behaves like a M elsewhere.
Ralph Lauren — classic American cut, generous through the chest and sleeve. Shirts especially.
Max Mara — the coats are cut for layering over tailoring. I almost always take clients down a size in the icon coats.
Ganni — boxy, cropped and wide-shouldered. The proportions are the design, but the bust measurement runs well above the label size.

My own expensive lesson

Years ago I bought a Max Mara camel coat in a UK 12 in a January sale, delighted with myself, and wore it exactly four times. It swamped me. The shoulder seam sat halfway down my arm and no amount of belting fixed it. A tailor eventually told me the honest answer: it was two sizes too big and couldn't be rescued. I sold it on and rebought a 10 the following year. That coat is still in my wardrobe eight years later.

The win, for balance: I once bought a COS wool blazer in a size 8 when I'd normally take a 12, purely because a shop assistant insisted. It's the single most-worn thing I own.

How to size yourself in a brand that runs large

Judge by the garment, not the brand. COS trousers and COS coats behave completely differently.
Check the shoulder seam first. If it's dropped by design, size down. If it's meant to sit on your shoulder point and doesn't, it's too big.
Woven fabrics don't forgive. Linen, cotton poplin and wool have no recovery, so a generous cut simply reads as loose.
Buy for the largest measurement and have the rest taken in. Cheaper and better than trying to let something out.

Where to shop, by tier

High street

COS — architectural, minimal, superb wool and cotton. Size down.
Marks & Spencer — reliable basics and knitwear, genuinely generous fit.
Boden — colour, print and easy dresses with a roomy cut.
Seasalt Cornwall — soft, relaxed, brilliant organic cotton.
White Stuff — gentle, forgiving shapes and a warm everyday palette.
Fat Face — weekend casualwear with a comfortable, oversized lean.
Gap — denim and sweatshirting, but expect the sizing to run big.
Monsoon — occasionwear that's generous through the bust.

Premium

Toast — considered, oversized, exceptional natural fabrics.
Hush — relaxed British staples, easy through the body.
Ganni — Copenhagen cool with a deliberately boxy fit.
Brora — cashmere cut with generous ease. Size down for a neat look.

Luxury and designer

Max Mara — the definitive camel coat, cut for layering.
Totême — quietly oversized Scandinavian tailoring.
Ralph Lauren — classic, roomy American proportions.

Two independents worth knowing

Lucy & Yak — Brighton-based, best known for dungarees, with a genuinely relaxed and inclusive fit.
Kowtow — New Zealand organic cotton label with beautifully boxy, drapey shapes that run big by intention.

How Tellar takes the guesswork out of it

This is precisely the problem Tellar was built to solve. It's the UK's leading sizing tool: you measure once and your body is matched instantly to over 1,500 brands, so you never look at a size guide again.

Measure once — bust, waist and hip, or simply enter a brand size you already own and wear.
Use the Store Size Lookup tool to get your exact size in any brand, including COS, Reiss, Everlane, Arket and hundreds more.
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There's also the Tellar Fashion Hub, a library stacked with free posts from our stylists. Honest, unbiased, independent and always free — style advice, top picks and best brands.

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