Boux Avenue Sizing: Does It Run True to Size?

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

Yes — Boux Avenue runs broadly true to size, but with some important nuances depending on what you're buying. Bras tend to have a snug, firm band (size up if you're between bands), knickers in fitted lace styles can run slightly small, swimwear often runs small in the bust, and nightwear is cut with a comfortable, relaxed ease. Get those distinctions right and Boux is actually a very wearable brand — but get them wrong and you'll be fighting a bra that digs in or knickers that feel like a second skin in all the wrong ways.

I've had my fair share of lingerie sizing disasters — the balconette that gapped at the top despite being "my size," the bodysuit I couldn't get off without a small crisis. So let me save you from the same fate with an honest, detailed breakdown of how Boux Avenue sizing works across every category.

About Boux Avenue

Founded in 2011 by Theo Paphitis (yes, him from Dragon's Den), Boux Avenue was designed to fill a gap on the UK high street — beautiful, affordable lingerie that didn't compromise on style or size range. They offer bras from a 28 back through to a 40 back, and cups from A through to H in many styles. Their stores are known for bra fitting services, and online they've made a real effort with sizing guides and transparent product descriptions. It's a genuinely lovely brand — but sizing still needs a little navigation.

Boux Avenue Bra Sizing: What to Know

This is where most people trip up, and honestly, bra sizing is its own world regardless of brand. Here's the Boux-specific picture:

Bands run firm and can feel tight — many customers find Boux bands softer after a few wears, but if you're on the cusp between two band sizes, start on the looser end. A new bra should fasten comfortably on the loosest hook so you have room to tighten as the elastic relaxes.
Cups vary by style — T-shirt and balcony bras tend to run closest to true size. Deep plunge styles are more variable depending on your breast root width. If the centre gore isn't sitting flat, try a cup up rather than a different size entirely.
Moulded cups — if you're getting gaping in a moulded style, it's usually a shape issue rather than a size issue. The cup mould may not match your breast shape; try a different style rather than sizing down.
Fuller bust fit — Boux goes up to an H cup which is genuinely commendable, but reports suggest their in-store fitters don't always have the specialist knowledge to support a larger cup. If you're a DD+ wearer, I'd honestly recommend getting properly fitted first at a specialist like Bravissimo, then using those measurements to shop Boux online.
Bralettes — sized in XS–XL alpha sizing. If you're fuller-busted and between sizes, go up for depth and comfort.

My tip: When buying Boux bras online, order your usual size and a sister size — for example, if you're a 34D, also try a 32DD. They offer free returns so it's easy to compare fit from home without the changing-room faff.

Knickers & Lingerie Bottoms

For the most part, Boux knickers fit true to size. However:

Fitted lace styles can run slightly small — particularly thongs and cheekies in stretch lace. If you're between sizes, go up.
Shorts and fuller briefs tend to be the most accommodating and generally hit true to size.
The multi-buy knicker deals (3 for £18, 5 for £25) are genuinely great value — just make sure you've checked the style-by-style stretch before committing to a full set.

Bodysuits

Bodysuits at Boux are structured and sit snug by design — which is part of their appeal. That said, if you have a long torso, size up. The gusset on a bodysuit is quite unforgiving if the rise is too short, and no one wants to be doing a full yoga pose just to get dressed. Standard torso lengths tend to find their usual size works well.

Swimwear Sizing

Boux's swimwear collection is gorgeous — the prints and cuts are really well-considered. But sizing-wise, it can run small, particularly in the bust. My honest advice:

If you're a smaller cup (A–C), you'll likely find your usual size works.
If you're a D cup or above, size up in the swimsuit or bikini top — or look specifically for their swimwear with underwired cups, which tend to offer better bust support and more accurate sizing.
Bikini bottoms are generally more forgiving and tend to run true to size.

Nightwear & Pyjamas

Good news here — Boux nightwear is cut with a relaxed, comfortable ease. If anything, it runs slightly generously, which for pyjamas is exactly what you want. Most customers find their usual size perfect, and many TikTok reviewers have noted the quality is genuinely impressive for the price point. Their satin pyjama sets in particular have become something of a sleepwear staple. If you prefer a closer, more fitted silhouette in your nightwear, you can safely size down without issue.

How to Find Your Boux Avenue Size

Because Boux spans so many categories — each with slightly different fit logic — the most reliable approach is to start with your exact body measurements rather than assuming a size across the board. Your bra size and your knicker size and your bodysuit size can all be slightly different, even within the same brand.

Find Your Exact Boux Avenue Size — Free & Instant

This is exactly why I recommend Tellar.co.uk — the UK's leading free sizing tool. It matches your exact measurements to 1,500+ brands in real time, so you're not guessing across categories or relying on generic size guides.

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Best Boux Avenue Alternatives — Other Brands to Consider

Love the aesthetic but want to compare? Here are the brands I'd recommend alongside Boux, depending on your budget and what you're shopping for:

High Street

M&S — the undisputed queen of high street lingerie. Their bra fitting is among the best on the high street and sizing is impressively consistent. Brilliant for everyday T-shirt bras and seamless knickers.
ASOS — enormous range spanning budget-friendly basics to fashion-forward sets. Great for bralettes and loungewear-adjacent styles. Sizing can vary by brand sold through their platform, so check individual product sizing.
Next — underrated for lingerie. Consistently good bra quality, particularly their non-wired and full-cup styles. Sizing runs reliably true to size.
H&M — excellent for affordable basics and seasonal prints. Their bralettes and soft-cup styles are particularly good value and tend to run true to size.
Calvin Klein — the go-to for clean, minimal basics. Their underwear runs true to size and the quality is excellent for everyday wear. Their bralettes and triangle tops are a wardrobe staple.
Tommy Hilfiger — solid everyday knickers and lounge sets with that classic American feel. Runs true to size and the cotton-blend fabrics wash brilliantly.
Urban Outfitters — great for trend-led bralettes, mesh styles and co-ord loungewear sets. Alpha sizing on most pieces; generally runs true to size.
Topshop (via ASOS) — the archive of Topshop lingerie sets lives on through ASOS and still turns up some brilliant pieces. Good for trend-forward styles at affordable prices.

Premium & Independent Picks

Bluebella — one of my favourite independent UK lingerie brands. Their aesthetic sits between fashion and intimates — intricate lace, considered design — and sizing is detailed and accurate. Well worth exploring if you want something a little more special.
Playful Promises — a fantastic independent UK brand specialising in inclusive sizing (up to a UK 26 / H cup) with genuinely beautiful designs. Their size guidance is thorough and their customer service is brilliant. A must-know brand.

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