What is sizing like at Oséree?

Oséree runs on the snug side — most pieces come up slightly small, particularly across the bust — so if you're hovering between two sizes, take the larger one. The brand itself quietly admits this in its size guide, advising intermediate sizes to round up, and after years of dressing clients (and myself) for sun-soaked holidays, I'd back that up entirely. This is beautifully made Italian swimwear with a body-skimming, slightly compressive fit — gorgeous on, but not the place to take your "usual" size on faith.

So, does Oséree come up small?

In a word: yes, a little. Oséree is made in Italy and cut to flatter rather than to forgive, which means the fabric sits close and holds you in. It's the swimwear equivalent of a fitted Italian blazer — designed to look sculpted, not slouchy. Here's what to expect:

The bust is the pinch-point. Triangle and balconette tops in particular run tight across the chest. Fuller busts will almost always want to size up on the top half.
Bottoms are truer to size than the tops, though high-leg and cheeky cuts sit higher and narrower than UK high-street briefs.
The famous Lumière metallic fabric has very little give. That shimmery lurex finish looks incredible but doesn't stretch like a standard matte swim fabric, so don't expect it to "give" once you're wearing it.
Sizing is Italian (XS–L). An Oséree Small is not a generous Small — it's a true, neat Italian small.

The Oséree fit, piece by piece

Because the cut varies so much across the collection, it's worth knowing your piece before you order:

Lumière two-pieces & sets — the signature shimmer. Stunning, but the firmest fabric in the range. Size up if you're borderline, especially on the top.
Maillots & one-pieces — generally the most reliable fit and the easiest to size. The high-cut leg elongates beautifully; if you're long in the body, check the torso measurement so it doesn't pull.
Latex & balconette styles — structured and supportive, and closer to true-to-size, but unforgiving if you guess wrong.
Kaftans & cover-ups — the one place Oséree is relaxed and generous. Buy your normal size and enjoy the drape.

A quick confession on the fashion-fail front: I once ordered a Lumière set in my "safe" size for a trip to Puglia, convinced shimmer fabric would be stretchy. It was not. The bra was a good half-size too tight and I spent the whole flight regretting it. Ordered the size up, problem solved — and that two-piece has since photographed better than anything else I own. Lesson learned, and now passed on to you.

How to nail your Oséree size

My styling shortcuts for getting it right first time:

Lead with your bust measurement, not your dress size. With Oséree, the chest decides everything.
Size up on Lumière and metallics, stay true-to-size on matte fabrics and kaftans.
If you're a different size top and bottom, buy separates or a set that lets you mix — never compromise the bust to fit the brief.
Order two sizes if the retailer allows free returns. Italian swim is worth trying side by side.

Where else to shop if you love the Oséree look

If Oséree's polished, holiday-glamour energy is your thing, here's where I'd send clients across every budget.

High street

Marks & Spencer (M&S) — the best high-street swim for genuine bust support and tummy-smoothing one-pieces.
Boden — joyful prints and flattering, properly-engineered shapes that don't dig in.
Seasalt Cornwall — coastal, sustainable swim with a relaxed, wear-all-day fit.
Hush — pared-back, chic swimsuits in that quiet-luxury palette Oséree fans love.
Anthropologie — the closest high-street hit for statement, embellished, resort-y pieces.
Whistles — elevated minimalist swim with a grown-up, sculptural cut.
Monsoon — embellished and beaded resortwear if you want a bit of drama for less.
Phase Eight — clever shaping swimwear with built-in support and a true-to-size fit.

Premium

Ganni — Copenhagen-cool swim with playful prints and a fashion-forward edge.
Totême — sculptural, minimalist one-pieces for the understated-luxury crowd.
Me+Em — beautifully flattering, well-supported swim engineered to actually fit real bodies.

Luxury & designer

Eres — the French gold standard in luxury swim; faultless fabric and fit.
La DoubleJ — maximalist Italian prints and the spiritual sister to Oséree's glamour.
Zimmermann — romantic, intricate designer swim for full holiday drama.

Two to discover (my left-field picks)

Form and Fold — an Australian independent making structured, bust-size-inclusive swim — the answer to Oséree's snug-top problem if you're fuller-chested.
Casa Raki — a sustainable independent crafting elegant, timeless pieces from recycled fabrics, with a fit that's quietly forgiving.

Never guess your swim size again

Swimwear is the hardest thing to size online, which is exactly why I built Tellar — the UK's leading sizing tool. Match your body to 1,500-plus brands instantly and never squint at a confusing size guide again.

Measure once — using your bust, waist and hip, or simply your existing size in a brand you already own.
Use the Store Size Lookup tool to get your precise size in any label — Oséree, COS, Reiss, Everlane, Arket and more.
Always free, no downloads, works straight in your browser.

There's also the Tellar Fashion Hub — a library stacked with free posts from our top stylists. Honest, unbiased, independent and always free: style advice, top picks and the best brands for every body.

A few of my favourite reads to take you further:

Find your exact Oséree size in seconds

Your body, matched to 1,500+ brands. Always honest, always unbiased, always free.

Try the Store Size Lookup → Visit Tellar →