What Is Sizing Like at Oasis? An Honest Stylist's Guide

By Ella Blake — Senior Fashion Stylist & Founder | Tellar — Always honest, unbiased & unsponsored.

Oasis sizing runs slightly small, particularly in fitted dresses, structured blazers, jumpsuits and anything in satin or non-stretch fabric — but jersey tops, knitwear and flowing midi dresses tend to come up true to size or even a touch generous. Their cut is built around the classic UK adult silhouette rather than the youth-skewed fits you'll find at Zara or Topshop, which means most women shopping there for the first time get caught out by the more tailored pieces and pleasantly surprised by the casualwear.

Now Oasis is online-only after the high street closures a few years back, which makes getting your size right even more important — there's no popping into a fitting room any more. So let's go through it properly, item by item, the way I'd brief a client.

I had a bridesmaid styling job last summer where the bride had bought all five of her girls the same Oasis satin midi in their "usual" UK size. Three of them couldn't get the zip up. We ended up doing an emergency Oasis re-order in a size up the next day, paying for express delivery, and then I had to take in two of them at the waist because the bust now fitted but the rest swam. Lesson learned: with Oasis satin and anything cut on the bias, always go up. Always.

How Oasis Sizing Actually Fits — Category by Category

Dresses

Casual jersey & flowing midi/maxi dresses: true to size. Their viscose midi range is genuinely one of the better-fitting on the high street and works well across a 10–18.
Bodycon and pencil dresses: size up. The cut is unforgiving and the fabric content rarely has enough elastane to give you room across the hip.
Satin and silk-effect dresses: always size up. Satin sits on top of you rather than skimming, and Oasis cuts theirs on the snug side of the silhouette.
Wrap dresses: usually true to size, but check the bust measurement — a generous chest will pull the wrap open.

Tops & Blouses

Jersey t-shirts and casual tops: true to size, occasionally a touch generous.
Woven blouses (no stretch): size up if you're between sizes — the shoulder fit is the giveaway.
Statement sleeve and ruffle styles: size as normal — the volume sits in the design rather than the body.

Tailoring, Blazers & Jumpsuits

Blazers: size up. Oasis blazers run narrow across the back and through the bust.
Tailored trousers: true to size in the waist but can sit slim through the thigh — size up if you're curvy below the waist.
Jumpsuits: size up, especially if you're tall or long in the torso. The proportions on Oasis jumpsuits are cut for an average-to-petite frame.

Knitwear & Outerwear

Jumpers and cardigans: true to size or slightly generous — perfect if you like to layer.
Coats: size up if you wear chunky knitwear underneath. Their tailored coats are cut close.

Jeans & Denim

Oasis denim runs broadly true to size, but their styles tend to be designed with a fairly low rise compared to the new high-rise wave at the rest of the high street. If you usually wear a 12 in jeans elsewhere, you'll likely wear a 12 here too — but check the rise carefully, because a low rise in a non-stretch denim is one of the quickest routes to a return.

How Oasis Compares to Other High Street Brands

In my experience styling clients, Oasis sits roughly between the slim, youth-cut sizing of Topshop and the more generous, classic cuts of Hobbs or Boden. Warehouse (their nearest cousin in style and price) sizes almost identically. Whistles tends to run a touch slimmer through the bodice. Mint Velvet is consistently more generous than Oasis, particularly in dresses and knitwear, while LK Bennett is similar in tailoring but with a more polished finish.

The Best Alternatives to Oasis — My Stylist Picks

If you love the Oasis aesthetic — feminine, work-meets-occasion, that "polished but pretty" energy — but want better fit consistency, or you just want to widen your shopping list, these are the brands I genuinely send clients to.

High Street Alternatives

Warehouse — The closest stylistic match to Oasis on the high street, with very similar sizing and a slightly trend-led edge. If you can't find what you want at Oasis, start here.
Coast — The go-to for occasion wear at this price point. Their bodycon and bridesmaid pieces are far better cut than Oasis equivalents and the satin handles much more like a premium fabric.
Monsoon — For feminine occasion and holiday dressing. Their embroidery and embellished pieces are far better than anything Oasis is putting out at the moment, and the cut is more generous through the bust and hip.
Mint Velvet — The relaxed-luxe alternative. Everything is cut a touch more generously, the fabrics feel richer, and the styling is more "off-duty modern woman" than Oasis's "boardroom-meets-Friday-night".
Ted Baker — A bolder, print-led alternative. Sizing is slimmer than Oasis (their numbering runs 1–5 rather than 8–18), so check carefully — but the workmanship is a noticeable step up.
Hobbs — For polished workwear with reliable, grown-up sizing. Where Oasis tailoring feels sharp but slightly stiff, Hobbs feels fluid and considered.
Boden — More forgiving cuts, a touch more colour and print, and far better sizing consistency. The dress fit in particular is a revelation if Oasis bodycon styles never quite work on you.
LK Bennett — A natural step up for the working Oasis customer. The blazers and shift dresses are cut beautifully and the fabrics last far longer.

Premium Picks

Hush — Relaxed luxe at its best — easy-elegant pieces with a softer, more generous fit. Great for the Oasis customer who is moving away from structured tailoring and into something more effortless.
Claudie Pierlot — Parisian-girl polish with feminine details. Sizing runs slimmer than Oasis (French cut), so size up — but the quality and longevity justify it entirely.

Luxury / Designer

Max Mara — The investment evolution. If you've worn Oasis tailoring for years and are ready for one really beautiful blazer or camel coat, this is where I'd send you.
Self-Portrait — The occasion-wear upgrade. Their lace and crepe midi dresses are exactly the silhouette the Oasis customer reaches for — done at couture-adjacent level. Sizing runs true to European standard, so check before ordering.

Two Independent Brands Worth Knowing

Damson Madder — A brilliant young British indie label that has quietly become a stylist favourite. Sustainable, trend-led, joyful — and their cut is far kinder than Oasis on the curvier hip-to-waist ratio. If you want something a bit more "now" with a clean ethical backstory, this is it.
Aligne — A London-based contemporary brand that sits exactly where the Oasis customer is heading: grown-up, considered, beautifully tailored without being stuffy. Their blazers and trousers are some of the best-cut pieces I've fitted on clients this year.

Stop Guessing Your Oasis Size — Use Tellar

The honest truth about Oasis sizing is that it varies enough across categories that you genuinely can't rely on the label alone. That's exactly why I built Tellar.co.uk — the UK's leading sizing tool, matching your real body measurements to 1,500+ brands instantly, so you never have to second-guess a fitting room (or a returns bag) again.

Measure once — bust, waist, hip, or just use your existing brand size.
Use our Store Size Lookup tool to find your precise size in any brand — Oasis, COS, Reiss, Everlane, Arket and over 1,500 more.
Always free, always browser-based, no downloads or sign-ups required.

And the Tellar Fashion Hub is a free, fully searchable library of stylist-written posts — honest, unbiased, independent. Style advice, top picks, brand sizing guides — all free, all the time.

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