Demystifying The Double D Bra

Rebecca Aughton

29th Mar 2022

Demystifying The Double D Bra

What’s in a Size? Demystifying the DD…

If you asked the average woman on the street what a big cup bra size would be, many would say a C, even a D, possibly a DD because that’s just what most of us have been offered. But with 26 letters in the alphabet have you ever wondered why are we limited to just the first five?

A little history 

We’ve had some form of shaping of the female form since time began. From extra linens beneath woolen garments to whalebone and steel structures to shift shapes (and our organs!) to conform to the fashions of the day. When brassieres first came onto the market, cups and band sizes weren’t even used. Bear in mind that for many years before the launch of department stores, ladies with a disposable income to spend on clothing would be on best terms with their tailors or garment fitters. Fashion changed and went from bespoke apparel that fitted to form, to mass production and fitting as many as possible.

Bras as we know them, with cup letter sizing, came in from the 1930’s such as Warner’s Alphabet bras which put women in to one of four categories: A, B, C or D. However, this letter sizing wasn’t even adopted by many major manufacturers until the 1940’s and 50’s. Therefore, despite having garments resembling bras for over a century, the system we use for them wasn’t fully adopted until 50 years later. A lot of confusion can happen in 50 years, and frankly, it’s not got much better since.

Women have been lumped into using the same four letters of the alphabet to determine their size and sometimes identity: A cup is petite, B cup is sporty, C cup is plenty and D cup is voluptuous. What’s after D? For fear of offending customers, manufacturers simply doubled it to DD. As customers demand required a bigger cup than that, they tripled it. And quadrupled it. And quintupled it. And so on. Leaving us in the confusing mess we see in US bra sizing.

You can see in this image below that not every DD is the same and having the range of cup sizes available is essential to getting the right fit.

So sure, a DD can be classed as a big cup size, but only if it’s on a bigger band size too! And frankly, it’s not even that big – the average US bra size is 36DDD and from experience, with more than 90% of the population wearing the wrong size, it could be that that is just the best-selling size. From our experience, and knowing that average clothing sizes have increased too, it’s more likely to be in the 36 – 38 G+ category.

Not all cups are created equal 

With growing customer demand for better fit, and an increase in plus size bras especially in the last three decades, bra sizing ranges have increased to provide for fuller figures and fuller busts. Some European ranges double all their sizing past a D cup and some launch straight into the next letter.

Hands up who has bought a size 12 top in one store that was too small and then found a size 12 top in a different store that was far too large?! The same can happen in bras. Unfortunately, manufacturers around the world have not come to an agreement on bra sizing, much like the struggle for women’s clothing to be more standardized.

Different brands and different shapes of bras can come up differently – a balcony bra or plunge bra can fit smaller than a full cup bra. Did you know, even different colors of bras can fit differently – black bras tend to fit tighter than lighter colored bras because of the saturation of dyes used. Therefore, a US brand in 36DDD might fit you - as might a UK brand in 36F or a French brand in 36G. A professionally trained bra fitting expert will be able to tell you exactly which styles will suit your shape and make all the adjustments for the different brands on your behalf, taking out the stress of bra fitting.

What’s my size, sister?

When a woman is correctly fitted in a bra there’s a need to know – what size am I? Upon hearing the former 36C is now a 30F a switch goes off… An F cup? I can’t be an F cup! That’s huge!!!! And yet… it isn’t. Did you know that a 36C is practically the same volume in the bra cup as a 30F? That’s because of a nifty trick called sister sizing.

Sister sizing is where the volume of the bra remains the same, but the letter and number sizing changes.


[You can see from this table that as the band size increases, the cup letters decrease and each cup is not the same as the one next to it – a 34D is not the same as a 32, 36 or 38 D.]

[In this image of a 30F, 32E, 34D, 36C and 38B you can clearly see all the cups have the same volume but the band size changes. Again, as the band size increases, the cup letters decrease. You can see how a small back can be full busted (with much less space on the frame for the bust volume) but that it remains the same volume in the cup as a larger frame.]

Interested in learning more? You might enjoy our Fitting Room Chat with National Fit Director at Eveden Inc, Frederika Zappe, on our YouTube channel:

What’s in a size? Would a DD by any other name not be as sweet?

To misquote Shakespeare, does it really matter what cup or size we are? The name of a thing does not matter as much as the quality of the thing. Does your bra lift you and make you look slimmer? Does it no longer hurt your back and shoulders? Do you walk with your head held high, able to just get on with life and not constantly pulling or tugging on straps and cups? If the answer is yes, then it shouldn’t matter what size is on the label – because not even the label is right all the time. If the answer is no, keep reading!

I’m not in the right size – how can I fix this?

  • The back sizing is where all the support of a bra should come from. Check yourself right now with this easy tip: where’s your bra’s underband right now? Is it up between your shoulder blades or is it pulled down to your waist? The correct answer would be to be sitting in a parallel line around your body, just below your bust line and if it’s relatively new (meaning less than three months old) it should be fitting snugly on the loosest hook.
  • If you can pull your bra away from you at the front, that band is too loose. Remember that movement means mischief. Your bra should move with you, but not independently so. If you bend forward and everything spills out or shifts up, you’re in the wrong size!
  • Feel like your wires are forever digging into you or you have double the breasts on show that you saw this morning in the mirror? Your wires should be sitting flush at the center and almost under the center of your arm pit. Your bust should be fully encased by your cup. If you have lost fullness in your bust and feel like the cup is gaping at the top, try an alternative style like a moulded or balcony shape rather than decreasing the cup. You may still need the width for fit but not fullness!
  • Where are your shoulder straps? A telltale sign of wearing the wrong size - especially in the band - is when the straps keep slipping off your shoulders. If your frame/band size is actually a 36 and you’re wearing a 40, those straps will naturally be designed for someone who is two inches wider on each side.
  • Even if you’re tightening the straps to their shortest setting, you’re just pulling the back of your bra up, with the weight of your bust dropping down, giving the see-saw effect. Once that band is snugly fitted around you there’s no more drop, just lift!

These are just a few tips to getting your size right – but with all the different options out there, it can still be a bit of a minefield. If you would like to discuss your bra fitting needs with our national bra fitting expert with more than 25 years of experience, we’d be delighted to chat.

We fit all different body shapes and sizes and can take the guesswork out of the whole process for you. With more than 200 bra sizes stocked including plus size and full figure bras, we are passionate about giving every woman the Bra~vo Experience.

To book an appointment for your very own Bra~vo Experience visit our website and arrange an appointment there or call us at 248-582-7286

Click here to contact us and book your bra fitting appointment.

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