The Difference Between "Plus Size" and "Full Bust", and Why It Matters

by Estelle Puleston

Bra sizing is incredibly complex, at the most basic level because there are simply far more sizes to contend with. Where a major retailer sells women’s clothes in US 00-26 (that is 15 sizes) and shoes in US 4-11 (also 15 sizes), bras from Ewa Michalak, for example, come in well over 100 sizes, spanning 28A to 60GG. It helps to understand the complexity of bra sizing and the fact that bra sizes are identified on a matrix of band plus cup, as opposed to the linear scale of clothing or shoe sizing. Several blog articles discuss this (see Dreams and Underthings's post here FullerFigureFullerBust's post here, and BigCupLittleCup's post here for example).

It is only normal, therefore, that bras have been categorised into a range of smaller groups that share similar features: core sizes (also known as straight sizes), full bust (or DD+) and plus size being the most common.

Pictured: Comexim Mixed Colors Plunge bra (26DD to 44HH)

Today’s post is about full bust and plus size bras, because the two are not necessarily the same thing. I often see people say ‘plus size’ when they mean ‘full bust’ and vice versa, and I can understand why there’s some confusion. Plus size is sometimes called full figured, and full bust is often called D plus (regardless of band size). Here are definitions to help differentiate between them:

  • Full bust – any band size with a cup size of D or above, e.g. 28E or 36DD
  • Plus size – a band size of 38 or above, with any cup size e.g. 38A or 44H. In the latter case, the 44H bra is also a full bust bra.

Evidently there is some intersection between the two terms, but there are also cases, e.g. in the 38A, which is a plus size and not a full bust size.

So why is this difference important? Bras in different size categories have different manufacturing requirements, for example larger breasts (full bust) are heavier and therefore need more support to achieve the same shape as smaller bust sizes can get with just a bit of foam molding. Some techniques manufacturers use to achieve this support for fuller busts are additional seaming, side slings to bring breast tissue at the sides inwards, or thicker fabrics to increase the lifespan of a full-bust bra.

A plus-sized bra does not necessarily need so much focus on support. A person wearing a 40B for example may get all the support they need without complex seaming, but may have other requirements from their bra such as a wider band which would cut in less on a softer ribcage for a smoother line under clothing.

Pictured: Avocado Couture Valentina bra (28E-42F)

As the brand designing and manufacturing the bras, it may not make sense to customise the fit of a particular size if it’s one size at the end of your range. Often a bra that comes in A-F cup sizes for example will have design changes on the DD-F part of that range. However, if you’re making bras in A-DD only it may be prohibitively expensive and time-consuming to develop a more supportive version of the bra for the DD sizes only.

Speaking personally, I hover on the cusp of core and full-bust sizes, most often wearing a 30E or 32DD. There is a noticeable difference in the shape I get when wearing a 32DD from an A-DD brand, and a 32DD from a DD+ brand. Those from A-DD brands often have minimal seaming and give me a flat profile from the side, whereas those from DD+ brands are generally more focused on seaming and support and give me a much rounder shape – despite the bras being the same size.

Therefore it can be beneficial to seek out brands that specialize in your size category, rather than just those that happen to make your size. An exclusively plus-sized lingerie brand knows what a plus-sized customer wants and how to make it. A brand making A-DD cup sizes may not have access to a factory with extensive technical knowledge of DD+ construction. 

Pictured: Ewa Michalak HM Sekret Wiktorii bra (28B-42E)

This brings me onto the other reason that it’s important to have a distinction between full-bust and plus-size lingerie - it helps customers to find what they’re looking for. Whether searching on Google or reading a brand’s Twitter bio, labels such as ‘plus size specialist’ instantly tell customers whether or not their brand is for them.

Have you ever muddled up the terms ‘full bust’ and ‘plus size’? Do you find labels like this helpful when shopping for underthings?