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Bra Size, Fitting & 'Sister Size'


Do you get confused about your bra size? Don't know how fittings work? Heard of sister sizes but don't know what they mean? Let us shed some light on the topic. If I tell you to imagine a cup size D, what do you picture? Do you think of a specific size or volume of breast? I have spoken to women who didn't realise that if you pick up a bra in a size 28D and one in a size 38D you will get cups of different sizes.

So, what bra size am I?

All of us have gone to get our bra size measured at one time or another. You can even try this yourself at home. All you need is to wear a non-padded, everyday bra and have a tape measure to hand. Don't worry if it takes you a few tries to get it right, you might find it easier to ask for someone to help you out.

Start by measuring the underband size.

To do this you will need to place the tape measure flat, snug and level just beneath where your bra sits and read the measurement in inches. Next, if the measurement you just read is an even number you must add four inches onto this. If it is an odd number you must add five inches to this. This new number is your underband size.

Next we will measure the cup size.

[caption id="attachment_2404" align="aligncenter" width="461"]bust & underhand measure locations Bra Bust and Underband Measurement Locations[/caption] Use the same technique again, but this time around the bust. This is the fullest part of your breasts. Now time to compare this bust measurement to your underband measurement. Your cup size is determined simply by comparing the difference in measurements (in inches) between your underband and cup sizes. Who would have known.... A cup is a difference of +1 inch. B cup is a difference of +2 inches. C cup is a difference of +3 inches. D cup is a difference of +4 inches. And so on... For example, if you measure your underband size to be 30 inches and your bust size to be 38 inches, your bra size will be 34D. (30 + 4, with a difference of +4).

In that case, what sports bra size am I?

When it comes to sports bras, size is determined by the measurements above. However, personal preference plays a part also. Some women like to have their sports bra fitting tighter, whilst others prefer more breathing room. It is a misconception, that when you desire a tighter or looser fit to keep the cup size the same and change the underband size. This is where you will need to know your sister sizes.

Sister sizes explained.

[caption id="attachment_2400" align="aligncenter" width="3778"]Sister Sizes Explained Bra Sister Size Explained[/caption] If you're like me and experience that you can find bras of the same size from different shops fitting differently. You might and want to go up or down a size, this is how to do so. Take your size from the measurements taken above. If you desire a looser fit on the underband, increase your underband size by 2" but reduce your cup size by one letter. For example, if you are a 34D in this scenario, then your sister size is 36C. On the other hand, if you find that the band it too loose then you should take the opposite steps, reduce your underband by 2" and increase your cup size one letter and pick up your sister size of 32DD. If you were to pick a different size underband but keep the cup size to the same letter then you will notice this volume get larger and smaller too. This technique will alter your underband size but keep your cup volume consistent. Do you feel women are well informed about correct sizes? Do you have any further confusion around sports bras? Let us know in the comments below. Coming soon, telltale signs that your bra is not the right fit for you. In the meantime, read Do you know your sports bras? Mari.