Which Brands Get Sizing So Wrong?

The worst offenders are the online-first fast fashion retailers — ASOS Design, Boohoo, PrettyLittleThing, Shein and Missguided — followed by H&M and Zara, whose sizing shifts wildly between sub-lines and collections. Add to that the American brands that quietly inflate their labels (Gap, Old Navy, Abercrombie & Fitch) and the European houses cut to a narrower block than we expect here (Mango, Maje, Sandro), and you have almost every fitting-room meltdown I have ever witnessed in twenty years of styling.

Here is the part nobody tells you: none of this is illegal, or even unusual. There is no legal sizing standard in the UK or the EU. A “size 12” is a marketing decision, not a measurement. Brands set their own fit model, use different factories, and adjust the block whenever it suits them commercially. So when you order three size 12s and one fits, one swamps you and one won’t do up, nothing is wrong with your body. The label is the unreliable part.

The brands that get it most wrong

I’ve pulled these from years of client fittings, returns data and independent measurement studies — not from grudges.

ASOS Design – the single most inconsistent name in British fashion. ASOS uses dozens of different manufacturers for its own-label lines, and each one interprets the tech pack differently. Two size 10 dresses from the same drop can differ by several centimetres. Branded stock sold through ASOS is far more reliable.
H&M – notorious, and rightly so. Divided, Conscious and the main line are effectively three different sizing systems sharing one shopfront. H&M denim in particular runs at least one size small against the UK high street.
Zara – cut for a narrow, straight, Spanish fit model. Shoulders and hips are the pinch points. Zara also changes its block far more often than it admits, which is why the trousers you loved in 2023 fit nothing like this season’s.
Boohoo, PrettyLittleThing and Shein – effectively unsizeable. Stretch jersey hides a multitude of pattern-cutting sins, and quality control is minimal. Buy by garment measurement or don’t buy at all.
Gap, Old Navy and Abercrombie & Fitch – classic American vanity sizing. A US-converted UK 12 frequently measures like a UK 14. Flattering for a moment, useless for planning a wardrobe.
Mango, Maje and Sandro – not badly made, just cut small and short in the body. Continental sizing assumes a shorter torso and slimmer ribcage than the average British customer.
Luxury denim across the board – waistbands labelled in inches that bear little relation to your actual waist, because the fabric composition changes the fit entirely.

My own worst fail? A silk slip dress bought online for a wedding, size 12, from a brand I’d worn for years. It arrived cut for someone with a 25-inch ribcage and no bust. I had it altered the morning of the wedding by a tailor in Islington who charged me £80 and refused to make eye contact. The win, for balance: I now own four pairs of the same Me&Em trousers because I know, absolutely, that the size will not move between reorders. That is worth more than any trend.

Why it happens — the short version

No regulation. Sizing is voluntary and unpoliced.
Different fit models. Each brand fits garments on one real person, usually a size 10 or 12, whose proportions become the entire range.
Multiple factories. The more suppliers, the more drift. This is the ASOS problem in one line.
Grading shortcuts. Sizes above a 16 are often scaled up mathematically rather than re-fitted, which is why accuracy collapses at the larger end.
Vanity sizing. A deliberate flattery tactic. Today’s size 10 measures roughly like a size 14 from the year 2000.

The brands that actually get it right — where I’d shop instead

High street

M&S – the most sizing-consistent large retailer in Britain, and the benchmark I use when a client tells me their size. Main line and Per Una hold true season after season.
Next – reliable to the point of being boring, which in sizing terms is the highest compliment. Excellent for basics, tailoring and anything you’ll reorder.
Boden – British-cut, generous through the bust and hip, and honest about it in the product copy. Their fit notes are genuinely useful rather than decorative.
Seasalt Cornwall – cut for real proportions, with a relaxed but predictable block. Rarely a return.
Uniqlo – Japanese precision. Slim through the shoulder and short in the sleeve, but consistently so, which is all I ask.
Hobbs – proper British tailoring with a stable size 12 block. The place I send clients who need a suit that fits first time.
Phase Eight – strong on occasionwear, and the dress sizing genuinely matches the size chart, which is depressingly rare.
Jigsaw – a slightly narrow but very reliable cut, particularly in knitwear and coats.

Premium

Me&Em – obsessive about fit, with genuine long and petite options rather than a scaled hem. My most repeat-purchased brand for clients.
The Fold – workwear cut on a proper tailoring block, with garment measurements listed per style. No guesswork.
Cefinn – designed for a British body and a British working week. Sizing holds across the whole range.

Luxury & designer

Max Mara – Italian sizing done properly. Roomy through the shoulder on the coats by design, and utterly consistent year on year.
Joseph – clean, narrow and completely predictable. Once you know your Joseph trouser size you know it for life.
Toteme – oversized by intention rather than by accident, and the product pages say so plainly.

Two independents worth knowing

Kitri Studio – a London label producing in small runs on one stable block, so a size 12 dress fits like the last size 12 dress. Interesting prints, sane sizing.
Wyse London – cashmere and knitwear with a relaxed but honest fit, and unusually clear guidance on whether a style is cut close or loose.

My stylist rules for surviving bad sizing

Know three numbers. Bust, waist, hip. Written down, in centimetres, remeasured twice a year.
Buy the measurement, not the label. If a brand lists garment measurements, that beats their size chart every time.
Fit the widest part. Shoulders on jackets, hips on dresses, waist on trousers. Everything else can be altered cheaply.
Read the fit description. “Relaxed”, “oversized” and “boxy” are instructions, not adjectives.
Stop buying your “size”. The number is not a fact about you. It is a number a stranger chose.

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