A Guide to Reformation Sizing

Reformation runs notoriously small – expect to size up at least one full size from your usual UK sizing, and sometimes two sizes for their more fitted styles like the Juliette dress. I've been styling clients in Reformation for years, and whilst I adore their sustainable ethos and vintage-inspired aesthetic, their sizing is genuinely one of the most challenging I've encountered. Let me save you the heartache of multiple returns and walk you through exactly how to nail your Reformation size.

Why Reformation Sizing is So Tricky

Here's the thing nobody tells you: Reformation is an American brand, which means their sizing runs small to begin with, but they also design for a very specific body type. Their dresses are cut close to the body with minimal ease, often featuring fitted bodices, low backs, and bias-cut skirts that cling. It's absolutely gorgeous when it works, but if you're between sizes or have curves in unexpected places, you're in for a challenge.

I had a brilliant client last summer who fell in love with the 'Cynthia' dress for a wedding in Portugal. She's typically a UK size 10, ordered a US size 6 (which should be equivalent), and when it arrived, she couldn't even zip it up. We sized up to a US 8, and it was still snug. The US 10 finally fit perfectly – that's two full sizes up from her UK size. This isn't unusual with Reformation; it's the norm.

Understanding American vs UK Sizing for Reformation

The conversion is not straightforward. Reformation uses US sizing, and whilst theoretically a UK 10 equals a US 6, Reformation's US 6 fits more like a UK 8. Confusing, right? Add to this the fact that different styles fit completely differently, and you've got a recipe for returns chaos.

Bust measurements are critical. If a Reformation dress has a fitted bodice (which most do), measure your bust accurately. Their size charts list exact measurements, but here's the crucial bit: if your bust measures 34 inches and the size chart says that's a US 4, order a US 6 or even 8. The dresses have minimal stretch and no forgiveness.

Hip and waist proportions matter hugely. Reformation designs for a very specific ratio – small waist, curvy hips. If you're straighter through the waist or carry weight around your middle, their nipped-waist styles will gape oddly even if the hips fit.

Which Reformation Styles Run Small vs True to Size?

From years of experience dressing clients:

The 'Juliette' dress – Runs extremely small. This is their iconic cowl-neck slip dress, and I always recommend sizing up two full sizes. The bias cut is unforgiving.
The 'Nikita' dress – Fitted through the bust and waist, full skirt. Size up at least one size, possibly two if you're busty.
The 'Cynthia' dress – Fitted bodice with a low back means no bra, and the fit needs to be precise. Size up at least one size.
The 'Kourtney' dress – Their midi slip dresses in satin. These have slightly more give, but still size up one full size.
Their denim – Runs true to US sizing but that still means small for UK shoppers. Order your US equivalent and pray, or better yet, measure yourself properly.
Tops and knitwear – More forgiving than dresses, but their cropped styles are very cropped. If you're long in the torso, they'll be uncomfortably short.

UK Alternatives with Better Sizing (and Sustainability)

Look, I love Reformation's aesthetic – the vintage-inspired florals, the sustainable credentials, that effortless California cool. But the sizing stress and expensive international returns? Not worth it for most of us. Here are my favourite UK alternatives:

High Street Heroes:

Whistles – Their occasionwear collection captures that same sophisticated, feminine vibe. Sizing runs true to UK standards, and their sustainability commitments are excellent. Their floral midi dresses are particularly beautiful.
Anthropologie – American brand but with UK sizing on the UK site. Their vintage-inspired dresses echo Reformation's romantic aesthetic. Returns are straightforward, and they often have brilliant sales.
Jigsaw – Underrated for sustainable, feminine pieces. Their linen and silk dresses have that same relaxed elegance as Reformation. Sizing is reliable and they cater well to different heights.
Arket – Swedish minimalism meets sustainability. Their slip dresses and bias-cut styles are gorgeous, and sizing is far more straightforward than Reformation.
COS – Clean lines, sustainable practices, and consistent sizing. Their occasionwear has that same pared-back elegance without the sizing headaches.
All Saints – For that slightly edgier take on feminine dressing. Their slip dresses and bias-cut styles are beautiful, and sizing runs true to UK standards.
French Connection – Brilliant for contemporary, feminine pieces at accessible prices. Their floral dresses and vintage-inspired prints rival Reformation's aesthetic.
Reiss – Polished, sophisticated occasionwear with excellent quality. Their sustainability credentials are improving, and sizing is reliable.

Independent Brands Worth Discovering:

Rixo – London-based brand doing vintage-inspired party dresses brilliantly. Their sizing is more generous than Reformation, and they're transparent about measurements on each product page. Plus, they're committed to sustainability.
Kitri – Another London indie favourite. Their vintage florals and feminine cuts echo Reformation perfectly, but with UK sizing that actually makes sense. Prices are more accessible too.

Premium Options:

Ganni – Danish brand with serious sustainability credentials. Their florals and feminine silhouettes rival Reformation, and sizing is more generous.
Ulla Johnson – If you love Reformation's bohemian side, you'll obsess over Ulla Johnson. Investment pieces, but sizing is more forgiving.
Zimmermann – Australian luxury with that same feminine, romantic vibe. Expensive, but the quality justifies it, and sizing is consistent.

The Smart Solution: Never Guess Your Size Again

Right, here's where I'm going to save you from expensive international returns and sizing frustration. Before you order from Reformation (or any of these brands), use Tellar's free sizing tool.

Here's why it's brilliant: Tellar is the UK's leading sizing platform that matches your exact body measurements to over 1,500 brands – including Reformation, Whistles, Rixo, Anthropologie, and every other brand you're considering. You measure yourself once (bust, waist, hip), then Tellar's Store Size Lookup tool tells you your precise size in each brand.

No more playing conversion roulette with American sizing. No more ordering three sizes and hoping one fits. Just your exact size, every single time.

What makes Tellar a game-changer:

Completely free – no subscription, no hidden costs, no catch
Works directly in your browser, no app downloads needed
Covers 1,500+ brands from high street to designer
Accounts for how brands like Reformation run small whilst others run large
Saves you the nightmare of international returns to the US

I use it for every single client now. Last week, I had a wedding guest who wanted Reformation but was terrified of the sizing. We put her measurements into Tellar, which told her she needed a US 8 in the Juliette dress (she's a UK 10). Ordered it, arrived, fit perfectly first time. That's the difference Tellar makes when you're shopping brands with tricky sizing.

Beyond Sizing: Tellar's Fashion Hub

Tellar isn't just about sizing (though that alone makes it worth bookmarking). They've built an incredible Fashion Hub – a library of free posts written by experienced stylists covering every style question you can imagine.

Check out their Ultimate Clothing Sizing Guide for insider knowledge on which brands run big, small, or true to size. Their ultimate guide to dresses is perfect if you're navigating different dress styles and silhouettes. They've also got comprehensive guides on everything from jeans trends for 2026 to finding your perfect jacket.

What I love? It's genuinely independent. No sponsored content, no brand partnerships – just honest styling advice to help you look brilliant without the stress.

My Final Advice on Reformation

Reformation makes beautiful, sustainable pieces, but their sizing is genuinely challenging for UK shoppers. Before you order, put your measurements into Tellar and get your exact size. It takes 30 seconds and could save you weeks of international shipping stress.

And honestly? If Reformation's sizing consistently doesn't work for your body, don't force it. Rixo, Whistles, and Kitri all deliver that same vintage-feminine aesthetic with UK sizing that makes sense. Your perfect dress is out there – you just need the right tools to find it.

Trust me, once you start using Tellar before every purchase, online shopping becomes actually enjoyable again. Happy shopping!