The BIG Bra Deal

The Backstory

We’ve heard it repeatedly, most women are wearing the wrong bra size, and we just can’t get it right. A Huffington Post article states that, in an international survey of 10,000 women, 64% were wearing the wrong sized bra, with nearly half of them KNOWING that their bra was ill fitting. So if we’ve felt it, believed it, and now have proof of it, why is it that we have yet to correct our sizing issues?

The Misconception

Part of the problem comes from the common misconception about cup size. The incorrect stereotype reinforces that cup size reflects breast size: A’s are tiny, B’s are small, C’s are average, D’s are large, E’s are massive etc… However, the cup size on its own means absolutely nothing until it is paired with the band size. Cup sizes vary greatly between one band size and another, i.e., a 28D, 30D, 32D, 34D are different in bust/breast measurement by 1”, respectfully.

Unfortunately, many very popular intimate apparel brands simply don’t know how to accurately measure a woman for a bra. I calculated my own bra size with 10 different brands and received 10 different bra sizes! Furthermore, most of these sites carry a much smaller range of sizes, usually around ¼ of the sizes we carry at Impish Lee, making most women assume that they must fit into a particular size. Click here to learn how to accurately measure yourself for your true bra size, finally!

The Bra Sizing Parameters

All clothing is sized by scaling proportion, including bras, but the scale of a bra is not built around the cup, it is actually built around the band. The bra band is made to fit the size of your ribs, or ‘underbust’, and as the cups increase in each band size (from a 32A to 32B), the underbust measurement remains the same and the bust measurement increases. The cups follow a very straightforward formula:

A = Band Size + 1″, B = Band Size + 2″, C = Band Size + 3″, D= Band Size + 4″, etc.

This chart includes all the bra sizes that we carry at Impish Lee. For each row, every size listed in that row contains the same cup size: the 28C, 30B, and 32A all have the same amount of breast tissue.

Sizing Chart


The diagram below illustrates this relationship between cup sizes and band sizes, and how they makeup an overall bra size. You can see in the left column that the cup size remains the same as the band length increases. The right column illustrates a cup increase with a stagnant band size.

Bra Sizes Illustrations


Now that we can see how bras are sized, lets review some examples.

  • A woman wearing a 34D bra feels that the band is way too tight but the cups fit well. To adjust the band, she should try a size 36C, which has the same cup size as a 34D but is larger in the band by 2”.
  • A woman wearing a 36B bra has the bra band riding up in the back at the tightest hook, but the cups fit perfectly. To adjust the band, she should try a 34C, which has a smaller band measurement by 2”, but the same cup size.
  • Alternatively, if the band fits well, but the cup is too large or small, a woman would remain in the same band size but increase or decrease the cup letter, ie; from 34C to a 34D(larger breast tissue, same rib measurement) or a 34B(smaller breast tissue, same rib measurement).

Click here to see the post on how to determine if you’re bra is fitting correctly.

*It should also be noted that bra sizes also vary depending on country. Click here to view our international bra size conversion chart.

The moral of our Big Bra Deal story is that cup size does not reflect nor indicate breast size and vice versa. What matters is that you find a bra that feels comfortable and supportive, and one that fits your specific shape!

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6 thoughts on “The BIG Bra Deal

  1. I am surprised that you do not ask customers for overbust and breast-to-breast distance in the measuring guide. This has partially cleared up the “sister sizes” concept for me though.

    1. Hi Naomi,
      We will take more measurements with in person sizing but we find that it is very difficult to get some of these measurements accurately, especially the breast circumference measurement, which is a very helpful measurement to have for determining cup size!

  2. I’m confused about band size. This site’s sizing tool gave me a band size that was the same as my underbust measurement, but most other sites say to add 5 inches to your underbust measurement to determine your band size. So I’m a 30 according to this website but a 34-36 according to most others. So am I correct in assuming that your sizing system is completely different than other brands?

    1. Hi Suzanne, the adding 5 inches rule we believe is an outdated method. Based on your measurements a 30 band will fit you and offer the most support, however, you may be more comfortable sizing up your band if that is what you are used to.

  3. On your web site you do not mention bra strap length. My current bra’s have about a 15″ length strap at its longest measurement, but I need a longer strap. How do you meaure for strap length and are you able to make a bra with a long strap?

    1. Hi Carolyn, our bra straps are about 18-20 inches depending on the bra style and elasticity of the straps. They are also adjustable the full length of the strap. I hope this helps!

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