Shop Now New Bras Undies Lingerie Fit Blog Loyalty Program

how to find the right bra size

Have you ever scanned over the assortment of bra sizes in your lingerie drawer and thought about how much easier bra shopping would be if you could just waltz into a store, pick out a bra in ‘your size’, and know that it would fit perfectly without ever needing to try it on?

Or, conversely, do you always buy the same bra size, but find that some end up fitting better than others? Well, I’m here to tell you that it’s actually totally normal to wear a range of different bra sizes, and this actually makes it much easier to find your perfect fit!

First though, let’s look at the reasons why your bra size won’t always be the same.

Every brand has its own sizing system

The simple truth is that there is no one, universal list of ‘correct’ bra size measurements that every brand adheres to. Each lingerie brand will create its own set of sewing patterns, and grade them in-house to fit different sizes. And because bra sizing requires so much more precision than a looser-fitting garment – say, a t-shirt – even just a few millimetres of difference here can change the way the bra ends up fitting.

Sometimes the difference is more than just a few millimetres. One thing that bra designers and bra wearers can never seem to agree on is whether the band should be the same size as your underbust measurement or bigger than it. This means that some brands are making their 32D bras with a 32” band length, whilst others are labeling bras as 32D bras that only have a 28” or even 26” band length, designed to fit a smaller ribcage.

It doesn’t stop there. Once the first sample is ready, it will then be tried on a fit model. However, of course, no two models are identical and so each brand checks and refines its fit against a slightly different breast shape or size.

Converting an international bra size?

Thanks to the internet you can now buy a bra from pretty much anywhere in the world. However, different countries have different systems for labelling their bras.

After a D cup, UK sizes go DD, E, F, FF, G, GG and so on. European letters on the other hand don’t ‘double up’ and just continue E, F, G, H… meaning that a UK G is bigger than a European G – it’s five sizes beyond a D, rather than just three.

If you wear a larger cup size and buy bras from brands based in different countries, be prepared for a fairly significant difference in how they’re labelled!

how to determine bra size

Parfait Elissa Contour Strapless Bra P5011 in Black

Related Post: Find Your Perfect Fit With Our US to UK Bra Size Conversion Chart

The style of the bra affects the fit

Okay, so what about two bras by the same brand? Those at least should fit the same, right? Well, not necessarily. The style of the bra also influences how it fits you.

For example, let’s say your breasts are fuller at the base and shallower up top. A full-cupped bra which comes up high on your chest may gape at the top, meaning you need a cup size smaller than in a lower-rise balconette or plunge style bra.

The materials can make a difference too. A soft and springy lace won’t fit as firmly as a strong powermesh or non-stretch silk, so if the brand hasn’t adjusted their band length to compensate, you may find yourself sizing down in the band to achieve the same level of support.

Oh, and sizing up or down in the band from your usual? Then you’ll need to buy a different cup size too. See our bra sister sizing chart to find out more!

So why don’t we just create a standardised system?

I get it, never quite knowing if a bra is going to fit until you’ve tried it on is frustrating. Especially if you shop online. However, the lack of standardisation does have one significant benefit – it gives you more options to try until you find your perfect fit.

Bra sizing requires precision, but it’s still not an exact science. Cup sizes go up in lots of 1”, but in the real world of course we don’t grow and shrink in sudden, perfectly-sized 1” increments. No two pairs of 34B breasts will be completely identical, and if one of those people measures a fraction of an inch larger around the bust, then the same 34B bra will fit one better than the other.

But that’s the great thing about size variation between brands. It means there’s another 34B bra out there – maybe even by the same brand – that will fit the other woman better. Basically, if one type of bra doesn’t work for you, just try another!

Bodies don’t come in standardised sizes. Neither should our bras. Be glad that every brand’s bras fit slightly differently because it means that somewhere out there, there’s a bra that will be a flawless fit on you.

how to convert bra sizes

Parfait Sandrine Unlined Wire Bra P5352 in Cameo Rose

Related Post: Bra Shopping Guide: Tips For Buying New Bras

We Highly Recommend

Whether you’re shopping for new everyday bras or lingerie for a special occasion, it’s always a good idea to seek out a second opinion. We know how hard it is to find bras that fit well and feel good, especially when you’re doing it on your own. If you’ve ever felt unsure about your bra size or you just don’t know where to go to find good bras, it’s time to let a bra fitter help.

Many specialty lingerie boutiques offer bra fittings. Their expert bra fitters will take the pain and frustration out of bra shopping and do all the work for you. Even better, their product knowledge can save you time and money. Plus, they know where all of the best bras are hiding.

If you’ve struggled with finding bras in the right size, it’s time to make a change. Visit our specialty store locator to find a store near you and schedule an appointment.

Happy bra shopping!

Featured image lingerie:
Parfait Estelle Padded Bra P5231 in Black
Shop Now

Published by

Estelle Puleston

Estelle Puleston is the founder of, a blog dedicated to her love of lingerie. She works full-time as a copywriter and digital marketer for the lingerie and swimwear industry, and when she’s not doing that, she’s probably sewing or enjoying a good cup of tea.

Go Top