What Is Sizing Like at Rachel Gilbert? Your Complete UK Fit Guide

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

Rachel Gilbert runs in Australian sizing, which means UK shoppers need to size up by roughly one size — so if you're normally a UK 10, you'll most likely be a Size 1 (AU 8) in Rachel Gilbert, and you should reach for a Size 2 (AU 10) for the most comfortable fit. It sounds confusing, but once you've got your measurements to hand, it becomes much clearer — and that's exactly why using a tool like Tellar.co.uk is a game-changer for a brand like this.

Why Rachel Gilbert Sizing Trips People Up

I'll be honest — the first time I ordered a Rachel Gilbert piece for a client, I got it completely wrong. She was a UK 12, I ordered an AU 12 without properly converting, and when it arrived it was enormous. That's because Australian sizing doesn't directly mirror UK sizing — it runs about one size smaller in label terms, meaning you need to go one up. On top of that, the brand uses its own internal sizing scale (RG 0–5, or XXS–XXL) which adds another layer of confusion.

The good news is the clothes themselves are exquisitely cut. Rachel Gilbert is an Australian luxury occasionwear brand known for structured corsetry, beautifully draped gowns, and that very specific kind of polish that makes you look like you've stepped off a film set. It's a favourite for black-tie events, weddings, and red carpet moments — and if you get the sizing right, it's completely transformative.

The Rachel Gilbert Size Conversion Table

Here's how their sizing converts across international systems, based on measurements in centimetres:

RG SizeUK SizeAU SizeUS SizeEU SizeBust (cm)Waist (cm)Hips (cm)XXS / 0044030795886XS / 066232846391S / 188434896896M / 210106369473101L / 312128389978106XL / 41414104010483111XXL / 51616124210988116

Important: Rachel Gilbert measures each garment by hand, and fit can vary significantly between styles. Always cross-reference with the individual garment's fit notes.

How Different Rachel Gilbert Styles Actually Fit

This is where it gets really important, because not all Rachel Gilbert pieces are cut the same way. The sizing label is just your starting point — the garment type matters enormously.

Gowns & Corseted Dresses

These are the pieces Rachel Gilbert is most famous for, and they're the ones where you need to be most precise. The internal boning and corsetry structures mean the fit is very specific — particularly through the bust and waist. If you're between sizes, size up without question. I've seen clients lose a deposit on a dress hire because they were convinced they could squeeze into the smaller size. You can always take a gown in slightly; letting it out over built-in boning is a proper job.

Fitted silhouettes with internal boning: measure your bust and waist carefully
Between sizes? Always size up in a corseted gown
Strapless styles: your bust measurement takes priority over everything else

Mini & Midi Dresses

Generally these run true to size in terms of the Australian conversion — so the standard "size up one" rule applies. The fitted skirt styles can feel snug through the hips even if the bodice fits beautifully, so if you're fuller through the hip, size up. Asymmetric and one-shoulder designs also need a bit of thought around shoulder width — if you're broad-shouldered, the fit at the shoulder seam can pull.

Tailored Separates & Blazers

These are cut close to the body with minimal ease — no stretch, sharp tailoring. If you're planning to layer, or if you have broader shoulders, I'd go up a size here. The look is intentionally structured and fitted, and there really isn't any give in the fabric.

Bridal & Bridalwear

Rachel Gilbert has a gorgeous bridal offering and for these pieces, your exact measurements are absolutely essential. The hand-finishing and delicate construction mean alterations can be costly — so rather than getting close and hoping, get precise. Measure your bust, waist, and hips properly, then use Tellar to match.

My Top Tips for Buying Rachel Gilbert in the UK

Get your measurements first. I cannot stress this enough. The Australian sizing system is unfamiliar to most UK shoppers and a tape measure is your best friend here.
Read the individual garment fit notes. Rachel Gilbert provides style-specific guidance on their site — actually read it. It's there for a reason.
When in doubt, size up. Their pieces are designed to be tailored, so slightly too big is a far better starting point than too small.
Consider dress hire first. If you're investing in a gown for a one-off occasion, hiring the piece first (through a service like The Volte) lets you check the fit before committing to a purchase.
Contact their team. Rachel Gilbert's customer experience team is genuinely helpful for fit queries — don't be shy about emailing.

Want Rachel Gilbert's Aesthetic Without the Price Tag?

I love Rachel Gilbert, but at £400–£1,500+ per piece, it's not an everyday buy — and I wouldn't pretend otherwise. The good news is that the aesthetic — structured occasionwear, beautiful draping, sculptural silhouettes — is something that a few other brands do really well at more accessible price points.

High Street Picks

Coast — has always been one of the best high street names for structured occasion dresses. The construction is genuinely impressive for the price point and the silhouettes are very Rachel Gilbert-adjacent.
Reiss — sharp, polished occasionwear with excellent tailoring. Their corset-style tops and sleek midi dresses have real luxury feel without the luxury price tag.
Phase Eight — particularly strong for wedding guest and black-tie pieces. Lots of flowing, draped styles that sit beautifully on the body.
Whistles — understated but beautifully made. If you love the clean, architectural quality of Rachel Gilbert, Whistles delivers a similarly restrained elegance.
LK Bennett — a perennial favourite for special occasion dressing. Structured, flattering and always looks more expensive than it is.
Ted Baker — for the more overtly glamorous, embellished end of the Rachel Gilbert spectrum, Ted Baker delivers sparkle and structure at a fraction of the cost.
Hobbs — beautifully cut occasion wear with a classic feel. Great for the more tailored Rachel Gilbert pieces — the blazer sets and structured dresses.

Independent & Under-the-Radar Picks

Zeynep Arcay — a Turkish-born, Paris-based designer producing impeccably structured knitwear and bodycon occasion pieces. It's a real step up in craft and is genuinely comparable to Rachel Gilbert in terms of quality. Not cheap, but far less widely known.
Aje — another Australian brand, so the sizing logic is identical to Rachel Gilbert, which makes it easy to cross-shop. Aje has a similar sculptural, high-occasion aesthetic and their dresses regularly appear in the same editorial circles.

Premium Options

Roland Mouret — if you love the fitted, architectural drama of Rachel Gilbert but want a European designer with a different sensibility, Roland Mouret is the natural step up.
Self-Portrait — sits between high street and luxury and produces occasion dresses that genuinely rival Rachel Gilbert for impact at a slightly lower price point.

Never Get Your Size Wrong Again — Try Tellar Free

Rachel Gilbert's sizing can be genuinely confusing for UK shoppers — but it doesn't have to be. Tellar.co.uk is the UK's leading free sizing tool, matching your body measurements to over 1,500 brands instantly — including Rachel Gilbert, and every other brand on your radar.

✔ Measure once — bust, waist, and hips
✔ Use the Store Size Lookup tool — get your precise size in any brand, from COS to Rachel Gilbert, instantly
✔ Always free — no app download, works in-browser

Plus, explore the Tellar Fashion Hub — a library of honest, unbiased, unsponsored fashion guides from our stylists. Style advice, brand reviews, best buys — always free, always independent.

👉 tellar.co.uk | 👉 Store Size Lookup Tool