Bra Sizes Explained

Bra Sizes Explained

Bras are technical garments with complicated sizing works. This means that not all women who wear G cup bras are actual G cups. Bra sizing works can be quite confusing, that’s why we are going to explain further.

According to research, most women wear the wrong bra size especially when the cup letters doesn’t translate to cup volume. This is also why sometimes the measured and actual bra sizes differ.

Finding the Right Bra Size

Let’s first look at traditional bra sizing. The measurements are usually determined based on the cup size, which is the letter and band size in number. In this case, we use a tape measure wrapping it around the breasts and ribcage.

You can also opt to answer some questions that typically match you with a recommended bra style and size depending on the shape of your breasts. Both options should leave you with a letter and number which is now the bra size.

Read our guide on how to measure bra size. Alternatively, check the video below for the step by step instructions:

Determining Bra Cup Sizes

Determining the bra cup size is quite challenging. For reference, all cups with band size 34 are usually considered “true cup” sizes. This loosely translates to a 32AA being an AA cup just like how a 34B is typically a B cup.

Even so, a 34B, 32C, 30D and 36A have the same cup volume. All the three bra sizes are B cups regardless of the difference in letters. This is known as sister sizing in the lingerie world.

For reference, check the bra sizing chart below. The bra sizes across the same row have the same cup volume aka sister sizes. Let’s compare a cup size – women who wear 32D bra sizes are C cups. The easiest way to know your cup size on the chart is by locating the bra size then checking the letter it’s paired up with in the same row.

Bra Sister Sizes

30 32 34 36 38 40 42 44 46 48
30B 32A 34AA
30C 32B 34A
30C 1/2 32B 1/2 34A 1/2
30D 32C 34B 36A
30D 1/2 32C 1/2 34B 1/2 36A 1/2
30E (DD) 32D 34C 36B 38A
30E 1/2 32D 1/2 34C 1/2 36B 1/2 38A 1/2
30F (DDD) 32E (DD) 34D 36C 38B 40A
32E 1/2 34D 1/2 36C 1/2 38B 1/2 40A 1/2
30G (DDDD) 32F (DDD) 34E (DD) 36D 38C 40B
32G (DDDD) 34F (DDD) 36E (DD) 38D 40C 42B
32H 34G (DDDD) 36F (DDD) 38E (DD) 40D 42C 44B
34H 36G (DDDD) 38F (DDD) 40E (DD) 42D 44C 46B
36H 38G (DDDD) 40F (DDD) 42E (DD) 44D 46C 48B
38H 40G (DDDD) 42F (DDD) 44E(DD) 46D 48C
38I 40H 42G (DDDD) 44F (DDD) 46E(DD) 48D

Are Sister Sizes Important?

Sister sizes always come in handy when you are looking to make some adjustments on your actual bra size.

For instance, the band size is a bit loose but the cups fit perfectly. In this case, you’ll need to go up a cup size and down a band size so as not to interfere with the cup volume. If you only reduce the band size, the cups will be too small and vice versa.

A 36F and 34F have different cup volumes while a 34G and 36F have the same cup volume.

Get the drill? No? You are not alone.

Contact our team of experts to help you find a perfect fit.

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