So how specifically do bra sizes yes, really work? even if you recognize your own precise bra size, you might still right into one more one or two sizes. You’ll discover that this bras fit exactly or almost as well. Yet how can that be? Today, we space looking more closely at what all females should recognize – sister sizes.

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You have probably heard that four out of 5 women undertake the wrong size bra. As soon as we speak ‘wrong’ size, we mean a dimension that no fit in ~ all, for example when the bust spills over the sheet of the cup or the cup is fifty percent full. Sister sizes, however, space something totally different. The is once the wrong size is quiet the appropriate size. Sound complicated? that doesn’t need to be.

The magic relationship between cup and also band

To kind out what sister size are, we an initial need to go through just how the bra sizing device works. A bra has twin sizes – the tape size(measured straight under the bust and also given as a number, for instance 38) and the cup dimension (given together a letter, for example B-cup).

The cup is constantly proportional come the band size, i.e. It changes according come the increase in band. A B-cup with a band size42 walk not have the exact same volume as a B-cup through a band size34. The fact is that if you to fill the cup of a bra of dimension 40B v water, it will organize the very same amount as a bra of size 34F!

C-cup is not the same in every sizes


Sister sizes typical that the volume the the cup is the same in numerous band sizes. Because that example, 38C has actually the same size cup as 36D and also 34E.

This method that if you try a 34F-cup and also think the the cup fits well yet that that is too tight approximately the back, climate you can shot a bra through band size36. However instead of trying a 36 through a F-cup, pick 36E instead. 34F and 36E have the exact same cup volume. It is only the band dimension that has changed. If you shot a 36F, the cup will be too big but the bra will certainly fit friend well around the back.

The table below shows the connection – the orange fields have the exact same cup volume. The dominion of ignorance is simple – increase one tape size,down one cup size. Down one band size, increase one cup size.


Sister size – when more than one bra dimension fits

This is what is called a sister dimension – 38C is the sister the 36D and also 40B. Stop say that you have actually size 38C. If the bra has actually an elastic back, you can probably likewise wear a 36D together it will certainly stretch end time and also adapt to her body. If girlfriend think that 36D is as well tight approximately the back you can simply boost the one by a couple of centimetres using a bra extender in the hook and also eye fastening. You can thereby stay a 40B ~ above the innermost fastening so that is a small tighter.

The rule of thumb is simple:down one band size,up one cup size

When have to you no wear sister sizes So when need to you no wear a sister size? If you need help to elevator a heavy bust, that is no recommended come wear the ‘big sister’, i.e. The sister size with bigger tape size.There is a hazard that the bra will certainly be too loosened around the back and not administer the assistance it should. The is more common come go down a sister size (38C to 36D) than to go up, for that precise reason.

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The advantage of sister size If, after ~ a lengthy time of searching, girlfriend finally uncover a bra the you feel you just have to have but it is not accessible in your size, then it is perfect to inspect if a sister size is available. Increase one cup size, under one band size. Or the other means round. Shot for yourself. It nearly always works.