What Is Sizing Like at Karen Millen?

By Ella Blake – Fashion Stylist | Tellar Fashion Hub – Always honest, unbiased & unsponsored

Karen Millen runs slightly small — particularly in fitted, tailored, and corset-style pieces. If you're between sizes or have a fuller bust and hip, sizing up one is the safest call. In more relaxed styles and jersey knits, you'll generally find it true to standard UK sizing. The golden rule: always go by measurements, not the label.

I have a real soft spot for Karen Millen. It's the brand I reach for when I need to look polished at a wedding and don't want to look like everyone else in a Phase Eight wrap dress (no offence to Phase Eight, I also own three of them). There's something about the sculpted silhouettes and the quality of the fabric that just feels a cut above high street — and for the price, that's genuinely impressive. But over the years I've had my fair share of "why won't this zip do up" moments with them, so let me save you the panic.

The Sizing in Plain English

Karen Millen uses standard UK sizing — so you're looking at sizes 6 through 18 (or XS to XL in some ranges). On paper, that sounds straightforward. In practice, it's slightly more complicated, because Karen Millen has always had a reputation for a snug, sculpted fit. This isn't accidental — it's the whole point of the brand. Their designs are intentionally body-conscious, with waist seams, boning, structure, and tailoring built in to create a particular silhouette. All of which means that if you're wearing a UK 12 in Zara, you may well need a 14 in a Karen Millen fitted dress.

Where it gets more nuanced is across different product categories. Knitwear, jersey pieces, and more relaxed styles tend to be far more forgiving and often come up true to size. It's the structured dresses, tailored blazers, corset tops, and coats where you'll really feel the difference.

💡 Quick TipThe bust and rib area are where Karen Millen most commonly catches people out. If you have a larger chest, always check the bust measurement on the size guide and consider sizing up — you can always have a waist taken in if needed, but there's no fixing a too-tight chest on a structured dress.

Karen Millen Size Guide

Karen Millen SizeBust (inches)Waist (inches)Hips (inches)UK 6 / XS31–32"23–24"33–34"UK 8 / XS–S33–34"25–26"35–36"UK 10 / S35–36"27–28"37–38"UK 12 / M37–38"29–30"39–40"UK 14 / M–L39–40"31–32"41–42"UK 16 / L41–42"33–34"43–44"UK 18 / XL43–44"35–36"45–46"

Always use the above measurements as your guide rather than matching to your usual UK size elsewhere. Karen Millen's own size chart is your friend here — it tends to be accurate, and sticking to your tape measure rather than habit will give you a much better result.

Sizing by Garment Type

Not all Karen Millen pieces behave the same way, so here's a breakdown by category:

Fitted and bodycon dresses — this is where KM runs most noticeably small. If you're between sizes, go up. If the dress has no stretch and a back zip, definitely size up. I once confidently ordered my "usual" size 10 in a bandage dress and could barely sit down. Size 12 was perfect. Lesson learned (eventually).
Corset and structured tops — same advice as above. The boning and structure leave zero room for error. Measure your bust and go by the chart, not habit.
Tailored blazers and jackets — these can be narrow in the arm and shoulder. If you're broad-shouldered or have muscular arms, size up and take in the waist if necessary.
Coats — generally more true to size than the dresses, but if you plan to layer underneath, go up a size. The cuts are quite sleek and don't leave a huge amount of room.
Knitwear and jersey pieces — the most forgiving category. These usually come up true to size and are a great entry point if you're new to the brand and not sure where you fall.
Trousers and skirts — check both the waist and hip measurements. Karen Millen cuts tend to be narrower through the hips than many high street brands, so this one catches people out even when the waist fits fine.

Does Karen Millen Cater for Petite or Plus Sizes?

Karen Millen runs from UK 6 to UK 18 across most of their main range, which is a reasonably broad offering for the premium market. They don't have a dedicated petite line, which is a gap — the brand's longer hemlines and structured cuts can overwhelm a shorter frame. If you're petite, pay close attention to dress and coat lengths, and don't be afraid to have hems taken up; the quality absolutely warrants it. For plus sizing, the range stopping at a UK 18 is limiting, and KM would do well to extend this given the quality of the product.

What's Worth Buying at Karen Millen?

For me, the dresses are the hero pieces — specifically the structured occasion dresses and anything in their signature stretch crepe. These are the pieces that photograph beautifully, hold their shape all night, and genuinely look more expensive than they are. I also rate their coats enormously. A Karen Millen wool coat will last you years and still look sharp. Their knitwear has improved significantly too; the merino and cashmere-blend jumpers are proper investment pieces.

What to skip? The very trend-led, fast-turnaround pieces can feel less polished than the brand's core range. Stick to their classic silhouettes and you won't go wrong.

High Street Alternatives at a Similar Level

If Karen Millen's sizing isn't working for you, or you want to explore similar polished, feminine brands with great occasion dressing, these are my picks:

LK Bennett — the closest spiritual sibling to Karen Millen. Feminine, tailored, designed for women who want to look properly dressed. Excellent for weddings and smart events. Also slightly forgiving in sizing compared to KM.
Reiss — beautiful tailoring, similar price bracket, and a very clean modern aesthetic. Their dresses and blazers are consistently well-cut and come up fairly true to size.
Jigsaw — more understated than Karen Millen but similar quality level. Brilliant for investment knitwear, trousers, and relaxed tailoring that looks expensive without shouting about it.
Ted Baker — shares KM's fondness for feminine silhouettes and embellishment. Great for occasion dressing and floral prints, and generally true to size in our experience.
Whistles — lovely grown-up dressing with a quiet luxury feel. Particularly good for tailoring, silk blouses, and workwear that crosses over to evenings effortlessly.
Mint Velvet — pitches perfectly between relaxed and polished. A good option if KM's sculpted fits feel a bit unforgiving; Mint Velvet tends to be more generous in the cut.
Coast — this is where I'd send anyone who loves KM's occasion dresses but finds the sizing tricky. Coast does beautiful embellished pieces with a more forgiving structure — and they've genuinely upped their quality game.
Massimo Dutti — the most underrated name on this list. Spanish tailoring at its finest, and their dresses and blazers are exquisite for the price. Sizing tends to run true to UK.

Two Independent Brands Worth Discovering

Rat & Boa — a gorgeous independent label beloved by fashion editors and very much flying under the radar of mainstream shoppers. Their silk slip dresses and bias-cut pieces are everything Karen Millen's occasionwear aspires to be, and then some. Sizes tend to come up generously. One to bookmark immediately.
Nadine Merabi — a Manchester-born label that's become a cult favourite for anyone who loves a seriously glamorous occasion dress. Think sequins, sculpted silhouettes, and fabric that genuinely photographs like a dream. If you love KM's event dressing but want something nobody else will be wearing, this is your answer.

Unsure of Your Karen Millen Size? Let Tellar Sort It Out — Free.

Karen Millen's sculpted cuts mean your usual UK size won't always translate — and getting it wrong with a fitted dress is a painful (and expensive) business. That's exactly the problem Tellar.co.uk was designed to solve.

Tellar is the UK's leading free sizing tool, matching your exact body measurements to 1,500+ brands in real time. No more guessing. No more costly returns.

Measure once — your bust, waist, and hips, or use a size you already know fits you well
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