What Is Sizing Like at Marks & Spencer?

Marks & Spencer sizing runs true to size across most of its ranges — but with eight different sub-ranges, three length options, a dedicated plus size line, and a bra fit service that's practically an institution, there's a lot more to know if you want to get it right every time. I've been shopping M&S since before I could legally drink, and I've styled clients in it for years. Here's the honest breakdown.

I'll be upfront: M&S is one of those brands I have a proper soft spot for, not out of nostalgia (well, maybe a little), but because the quality genuinely punches above its price point. I've had clients come to me absolutely dismissive of it — "Oh, M&S is for my mum" — and I've watched their opinions change the moment they tried on a well-cut Autograph blazer or a pair of their slim straight jeans. The brand has quietly become one of the most reliable places on the British high street for everyday dressing. But the sizing? It takes a little getting to know.

The M&S Sizing Overview — What You Need to Know First

M&S sizes from UK 6 through to UK 24 across most ranges, which is genuinely inclusive and one of the brand's real strengths. The overall fit is true to size — if you're a UK 12 elsewhere, a UK 12 at M&S will generally fit. That said, there are meaningful differences between the sub-ranges that are worth understanding before you shop:

M&S Collection — the everyday range. True to size, relaxed-to-regular fit depending on the piece
Autograph — the premium range. Cut more precisely, often more structured. True to size and tends to be the most consistent fit in the entire store
Per Una — runs a touch generous, particularly through the body. If you're between sizes, size down here
Curve — M&S's dedicated plus-size range (sizes 18–28). Specifically designed for curvier proportions rather than just scaled up — this matters and makes a real difference to how the clothes actually sit

Length options across most ranges are Petite (for heights under 5'3"), Regular, and Long (for heights over 5'7"). This is one of the things M&S genuinely gets right that many high street brands still don't bother with properly.

M&S Size Conversion Table

M&S UK SizeEU SizeUS SizeBust (cm)Waist (cm)Hips (cm)634280–8260–6286–88836483–8563–6589–911038686–8866–6892–941240890–9370–7396–9914421095–9875–78101–104164412100–10380–83106–109184614105–10885–88111–114204816110–11490–94116–120225018116–12096–100122–126245220122–126102–106128–132

Sizing by Garment Category

This is where the detail really matters, because M&S is such a broad retailer. A size 12 in their dresses fits very differently to a size 12 in their tailoring — and knowing which way each runs could save you a frustrating return.

Trousers & Jeans

This is where M&S has genuinely improved enormously over the past few years. Their jeans in particular — the Sienna slim leg and the Lily slim cut — are consistently well-reviewed and fit true to size. Their tailored trousers in the Autograph range are excellent: true to size, clean through the thigh, and the length options (Petite/Regular/Long) make them actually workable for real bodies rather than the standard 30" inseam that suits approximately nobody.

💡 Stylist tip: M&S trouser waistbands can run slightly roomy — if you're between sizes, size down on trousers specifically. Their stretch fabric ranges have more give, so your usual size will be fine there.

Knitwear

M&S knitwear is brilliant value and I recommend it without embarrassment. Their Pure Cotton and Pure Cashmere ranges (yes, M&S does cashmere, and it's genuinely good for the price) fit true to size with a relaxed, comfortable cut. The Collection range tends to be slightly more generous through the body; the Autograph cashmere knits are more precisely cut. Either way, your usual size is a safe bet.

Dresses

Dresses vary considerably depending on style. Wrap dresses and jersey styles are very true to size and flattering across a wide range of body shapes. Structured shift dresses in the Autograph range fit like proper tailoring — true to size but with little ease, so if you're fuller on the bust, consider sizing up. Per Una dresses often run slightly loose through the waist — size down if you want more shape.

Lingerie & Bras

This deserves its own heading because it's arguably where M&S is most famous — and rightly so. Their bra range is extraordinary: they stock 60+ sizes and their in-store fitting service is one of the best on the high street. Sizing is very accurate and consistent. If you've never been properly fitted, honestly, walk into an M&S and let them do it. It's one of the more life-changing minor experiences available to women on a Tuesday afternoon.

Swimwear

M&S swimwear is another strong suit — particularly for women who want real support rather than an Instagram bikini. Sizing is true to size. Their tankini and swimdress ranges are particularly good for those who want more coverage without sacrificing style. For bikini tops, if you're a fuller bust, size up on the top and take your usual size on the bottoms — they do separates, which is genuinely useful.

Coats & Jackets

The Autograph outerwear range is where M&S really shines for investment pieces. Coats are true to size and well-constructed. One thing to bear in mind: M&S tailored coats are cut fairly slim through the shoulder, so if you have broader shoulders or plan to wear thick knitwear underneath, consider sizing up. The Collection range outerwear is slightly more relaxed and forgiving through the body.

Petite, Tall & Curve — Getting Proportions Right

This is genuinely one of M&S's biggest advantages over many high street competitors:

Petite (under 5'3"): Shortened hems, adjusted rise on trousers, repositioned waistlines on dresses — actually designed for a smaller frame, not just hemmed shorter
Regular: Best for heights roughly 5'3"–5'7"
Long/Tall: Extended hems and longer torsos. Works well for heights 5'7" and above
Curve: Dedicated plus-size range with adjusted proportions — wider hips relative to waist, more room through the thigh, longer back rise on trousers. Far better than simply scaling up a standard size

My Honest Verdict on M&S Sizing

M&S is one of the most consistent and reliable sizing experiences on the British high street — once you know which range you're in. The Autograph line in particular is impressively accurate and I recommend it to clients who want quality without the designer price tag. Per Una runs generous; everything else is broadly true to size. The length options are a genuine bonus that more brands should copy.

One thing I will say: M&S has improved its photography and styling significantly in recent years, which means the clothes look much better online than they used to. Trust the size guide, not your instinct to size up "just in case" — M&S is not a brand that cuts mean.

If You Love M&S — Other Brands Worth Knowing

M&S sits in a sweet spot that's hard to replicate exactly, but there are brands that cover similar territory brilliantly. Here's where I'd look:

High Street & Accessible Picks

Next — Probably M&S's closest high street rival for everyday essentials. Great basics, consistent sizing, solid petite and tall ranges, and their denim has genuinely improved
Phase Eight — The go-to if you want M&S-level quality for occasionwear and smart dressing. Beautifully cut dresses and occasion pieces with great size inclusivity
Hobbs — A natural step up from M&S Autograph for workwear. Impeccably tailored, sophisticated, and the kind of brand that makes you feel properly put-together without trying too hard
White Stuff — Excellent if you love M&S's quality casuals but want more personality and print. Very similar fit ethos, slightly more relaxed and bohemian in styling
Fat Face — Great for quality casual pieces: knitwear, casual trousers, and weekend-ready basics. Similar demographic to M&S Collection, with a slightly more outdoorsy edge
Seasalt Cornwall — A genuine gem for women who love M&S's quality but want something more independent. Beautifully made, sustainably minded, and with the kind of prints that genuinely make you happy to get dressed
Hush — For M&S lovers who want something a touch more considered and modern. Brilliant basics, great knitwear, and a relaxed-smart aesthetic that works effortlessly from home to office
Jigsaw — Sits neatly between M&S Autograph and a premium brand. Beautifully designed pieces with a quiet confidence — ideal for women who want investment-worthy wardrobe staples without going designer

Two Independent Picks Worth Knowing

Toast — A beautiful British slow-fashion brand that appeals directly to the M&S Autograph customer who wants something more artisan and considered. Think quality natural fabrics, relaxed silhouettes, and the kind of pieces you'll still wear in ten years. toa.st
Thought Clothing — An independent British brand built around sustainable fabrics and beautiful, wearable design. Fantastic for quality basics, great knitwear, and prints that feel genuinely original rather than trend-driven. Sizing is consistent and inclusive. wearethought.com

Stop Guessing — Find Your M&S Size Instantly with Tellar

M&S has eight sub-ranges, three length options, and a plus-size line — and your size might not be the same across all of them. That's exactly why Tellar exists. The UK's leading clothing sizing tool matches your measurements to over 1,500 brands instantly — including M&S, Next, Phase Eight, Hobbs and hundreds more. No more size charts. No more guesswork. No more returns.

Measure once — bust, waist, and hips, or enter your size in a brand you already know
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And while you're there, explore the Tellar Fashion Hub — a growing library of honest, unsponsored styling posts from our team of stylists. Free, independent, and always worth a read.

Visit Tellar.co.uk → Find My M&S Size →