What Is Sizing Like at O Pioneers?

O Pioneers sizing runs true to UK measurements but fits on the generous, forgiving side — their prairie-style dresses are cut with room through the bust, waist and hip, often with smocking or adjustable ties, so most women find their usual UK size works beautifully or that they can even size down. Because this is a small London label hand-making pieces in tiny runs, fit varies a little from style to style, so the smartest move is to go by your actual body measurements rather than the number on your everyday labels. Let me talk you through it properly.

First, who actually are O Pioneers?

If you've not come across them, O Pioneers are a genuinely independent, female-founded London label set up in 2019 by Clara Francis and Tania Hindmarch. They're a certified B Corp, and every piece is made in small runs by seamstresses in and around London using Liberty prints and deadstock luxury fabrics. The knitwear is hand-knitted by a team of home knitters dotted around the UK — including the founders' own mums, which I find rather lovely. So when we talk about sizing here, we're not talking factory-line uniformity. We're talking real, handmade clothing, and that changes how you should approach buying.

How the sizing actually fits

Their range spans roughly UK 6 to UK 18, and the cut is romantic rather than body-con. Here's what to expect:

The waist is your friend. Many of the dresses have elasticated smocking, tie belts or adjustable waists, so they flex with you. If you carry a little more on the tummy or hips, this is forgiving territory.
The bust can be the deciding factor. The high necks and gathered, puff-sleeve bodices are gorgeous, but if you're a fuller cup, that's the measurement to check most carefully — the body of the dress tends to be roomier than the bodice.
Length runs long. These are proper midis. If you're petite (5'3" and under, like a lot of my clients), expect them to sit lower on the leg than the model shots suggest.
Style-to-style variation is real. Because pieces are made in small batches, a size 10 in the Clara might feel a touch different to a size 10 in the Tania. Always check the individual garment, not just the brand average.

So what size should you order?

My honest advice: take your bust, waist and hip measurements with a soft tape, then match them to the specific dress you want. If you're between sizes, the forgiving cut means you can usually take the smaller one and let the smocking do the work — size up only if your bust measurement is the larger of your three. I learnt this the hard way years ago with a similar prairie label: I sized up "to be safe" on a smocked midi and ended up swimming in it, looking like I'd borrowed my nan's curtains. Sized to my actual bust the second time and it was perfect. Measure, don't guess.

Styling O Pioneers like a stylist would

The romance of these dresses can tip twee if you're not careful, so I always ground them. A chunky boot or a clean white trainer, a cropped leather or denim jacket over the top, and a structured bag rather than a basket. One of my favourite client wins was pairing an O Pioneers floral midi with black biker boots and a borrowed-from-the-boys oversized blazer — she'd written the dress off as "too sweet" and suddenly it was the best thing she owned. That's the trick: let the print be soft and make everything else a bit tougher.

Where to shop for a similar look

If you love the O Pioneers aesthetic — vintage florals, midi lengths, romantic but wearable — here's where I'd point you across the price spectrum.

High street

Boden — the closest high-street match for joyful prints and proper midi dresses with a flattering, true-to-size cut.
Seasalt Cornwall — soft, romantic prints in natural fabrics; relaxed, generous fit that suits the prairie mood.
Monsoon — beautiful occasion florals and feminine detailing, brilliant when you want the dressier end.
Joules — country-garden florals and easy day dresses with a forgiving, slightly roomy fit.
Hush — understated prints and easy silhouettes; their midis layer beautifully under a jacket.
Oliver Bonas — quirky, characterful prints with a fashion-forward edge and reliable sizing.
Phase Eight — feminine, occasion-ready dresses with structured fits that hold their shape.

Premium

Sézane — the Parisian queen of effortless romantic florals; cult dresses, slightly petite-friendly cut.
Kitri — bold, painterly prints in limited runs, which feels very in the spirit of O Pioneers.
ME+EM — elevated, grown-up femininity with genuinely thoughtful fit across heights.

Luxury & designer

The Vampire's Wife — the high-romance, ruffled prairie dress turned cult designer icon.
RIXO — hand-painted, vintage-inspired prints with that collected, one-off feel.
Doen — California-meets-heritage romanticism; beautifully made, conscious, covetable.

Two left-field independents worth knowing

Christy Dawn — a small-batch Los Angeles label working almost entirely in deadstock fabric, with the same honest, slow-fashion soul as O Pioneers.
Lowie — a long-running independent London brand doing playful prints and ethically made knitwear, perfect if you want something nobody else will be wearing.

How Tellar takes the guesswork out of it

Here's the bit that genuinely changes how you shop. Tellar is the UK's leading sizing tool — you measure once, using your bust, waist, hip, or even just an existing brand size you already trust, and we instantly match your body to over 1,500 brands. No more squinting at a size guide, no more guessing, no more "is this label generous or mean?" anxiety.

Measure once, using bust, waist, hip, or your existing brand size.
Use the Store Size Lookup tool to get your precise size in any brand — COS, Reiss, Everlane, Arket & more.
Always free, no downloads needed — it works straight in your browser.

The Tellar Fashion Hub

Beyond the sizing tool, there's 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 and every budget. A few you might like next:

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