What Is Sizing Like at Reformation?

Reformation runs small, and that's the honest answer before you spend a penny — it sits a touch snugger than most contemporary labels, particularly through the bust, ribcage and shoulders, and the cut is built on US sizing rather than UK. The good news is that it's a predictable kind of small once you know the fabric rules, so you very rarely have to gamble. I've been pulling Reformation for clients and for my own wardrobe for years, and I can tell you the brand fits beautifully when you order with a bit of strategy rather than hope.

First things first: it's American sizing

This is the bit that catches British shoppers out. Reformation is a Los Angeles brand and its number sizes (0, 2, 4, 6, 8 and up) are US numbers, not UK ones. As a rough mental shortcut, a US number is roughly four sizes below the UK equivalent — so the woman who buys a UK 10 on the high street is usually reaching for a Reformation 6. They also do lettered sizing (XS to XL), and in my experience those run truer than the brand's own size guide suggests, which I'd treat as a vague starting point at best rather than gospel.

Where Reformation runs small

The snugness isn't uniform — it's all about fabric and structure. Here's where I'd size up almost every time:

Anything fitted in a non-stretch fabric — silk, viscose, crepe and structured cotton have no give, so a fitted bodice can feel tight even in your usual size.
The bust and ribcage — this is Reformation's tightest zone. If you're a C-cup or above, size up on fitted styles or you'll get that pulling-across-the-chest look.
Denim — Reformation jeans are rigid with very little stretch, cut close through the thigh and waist. I'd go up at least one size, especially if you're curvier through the hips.
Fitted tops — the structured tops and bodysuits are deceptively small. A "small" can feel like an "extra small" if you've any shape to you.

Where it's actually very forgiving

It's not all sizing up. Plenty of Reformation runs true to size — and a few pieces are genuinely generous:

Linen styles — the breezy linen dresses and separates are the brand at its most reliable. Order your normal size and relax.
Smocked or elasticated backs — that stretch panel does the heavy lifting, so these forgive a multitude of sins. Take your smaller size here.
Knits and sweaters — often cut oversized to begin with, so no need to size up unless you want it slouchier.
Looser, floaty dresses — the relaxed silhouettes sit true to size and move beautifully.

Petite, extended and the length question

Reformation is better than most for body diversity. There's a dedicated petite line aimed at anyone under about 5'4", plus extended sizing that runs up to a 3X. Worth knowing: a lot of the regular-length dresses are genuinely long — gorgeous if you've height to carry them, but if you're petite the midis can read as maxis and the slits sit higher than you'd expect. If you're shorter, the petite range is the difference between a dress you live in and one that lives in the wardrobe.

A stylist's confession

My own Reformation fail was an early one: I bought a fitted crepe slip dress in my "usual" size for a wedding, convinced the size guide knew best. It zipped — just — and then I spent the entire reception holding my breath through the ribcage. Lesson learned. These days my rule is simple: order two sizes whenever I'm unsure, lean to the larger one in anything fitted or structured, and only trust my smaller size in linen or smocked styles. Returns are free, so there's no shame in a try-on at home. That single habit has turned Reformation from my most-returned brand into one of my most-worn.

If Reformation isn't quite your fit: where else to shop

Reformation's whole charm is that romantic, vintage-inspired, slightly-sustainable cool-girl thing. If the fit or the price isn't working for you, here's where I send clients for the same feeling at every budget.

High street

Nobody's Child — the closest spiritual match on the high street. Sustainable, deeply feminine, and the floral midis are practically a Reformation dupe at a fraction of the cost.
Ghost — the original bias-cut, slip-dress brand. If you love Ref's fluid silhouettes, Ghost does them with that fabric-led, drapey quality.
Monsoon — underrated for occasion florals and event dresses, with a softer, more romantic line than most of the high street.
Oliver Bonas — pretty, print-led pieces with proper attention to flattering cuts. Brilliant for wedding-guest season.
Hush — the relaxed, lived-in linen end of the Reformation aesthetic, done in a more forgiving fit.
Mango — the trend-led option. Their dresses move fast and nail the of-the-moment shapes for very little outlay.
Anthropologie — boho-feminine with that textural, slightly whimsical edge. Excellent for prints and standout occasion pieces.

Premium

Sezane — the French answer to Reformation. Vintage-inspired, feminine, beautifully made, and arguably more elegant. My top premium swap.
Ganni — the Scandi cool-girl alternative. Quirkier prints, playful shapes and a sustainability story to match.
Me&Em — British, polished and clever with proportion. Their pieces actually solve fit problems rather than create them.

Luxury / designer

Toteme — for the minimalist who wants Reformation's ease without the prints. Quietly expensive, endlessly wearable.
Max Mara — the investment end. If you've graduated from trend dresses to forever pieces, this is where the tailoring and fabric justify the price.

Two off the beaten track

And because I always like to send people somewhere they won't have thought of:

Rixo — the London independent for hand-illustrated vintage prints and dreamy tea dresses. If you love Reformation's romance but want something nobody else will be wearing, start here.
Faithfull the Brand — Bali-made, ethically produced and built for sun-drenched, holiday-dressing escapism. The linen and the prints are exactly the Reformation mood with a different passport.

How Tellar takes the guesswork out

Here's the thing — none of this sizing detective work should be your job. Tellar is the UK's leading sizing tool: you measure yourself once, using your bust, waist and hip — or simply your existing size in a brand you already own — and we instantly match your body to over 1,500 brands. No more squinting at size guides, no more "is this US or UK?" panic at the checkout.

Measure once, then use the Store Size Lookup tool to get your precise size in any brand — Reformation, COS, Reiss, Everlane, Arket and more.
It's always free, with no downloads — it just works in your browser.
And the Tellar Fashion Hub is a growing library of free posts from our stylists — honest, unbiased, independent and always free. Style advice, top picks and the best brands, all in one place.

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