There are times when the bra size you regularly opt for doesn’t fit you. Ever wondered why you face this situation in spite of buying the bra size you’ve bought a million times before? Well, remember that several factors such as the bra fabric, manufacturing variations, presence of underwires, cup shapes, and padding levels might contribute to the way a bra fits you. This is where the concept of sister size comes into play. 

What Is Sister Sizing?

  Bra Sister Size Chart

Sister sizes come to the rescue when a bra of your actual size doesn’t fit the way it should. In simple words, sister sizes are nothing but equivalent bra sizes. The cup volume of your actual bra size and sister size bra remains the same. This is the reason fitting experts suggest you to go for sister sizes when the original bra size doesn’t fit or is not available.

I Want to Know My Sister Size

Though there are four sister sizes for every bra size, you can ideally go for the nearest two while choosing sister size bras. 

Sister Size Up

For instance your bra size is 34C, your sister size up will be 36B (One band size higher and one cup size smaller). 

Sister Size Down

Similarly, you cup size down for 34C will be 32D (One band size lower and one cup size bigger)

     How To Calculate Your Sister Size?

Opt for a sister size up when the band of your actual size bra is tight or too small. On the other hand, go for a sister size down when your cup is too small.

Shyaway Bra Sister Size Chart

Looking for your perfect bra size? Shyaway bra size calculator will help you to measure your bra size.


Bra Size Sister Size Up Sister Size Down
30A 32AA 28B
30B 32A 28C
30C 32B 28D
30D 32C 28DD
32A 34AA 30B
32B 34A 30C
32C 34B 30D
32D 34C 30DD
32DD 34D 30DDD
34A 36AA 32B
34B 36A 32C
34C 36B 32D
34D 36C 30DD
34DD 36D 32DDD
36A 38AA 34B
36B 38A 34C
36C 38B 34D
36D 38C 34DD
36DD 38D 34DDD
38A 40AA 36B
38B 40A 36C
38C 40B 36D
38D 40C 36DD
40A 42AA 38B
40B 42A 38C
40C 42B 38D
40D 42C 38DD
40DD 42D 38DDD
42A 44AA 40B
42B 44A 40C
42C 44B 40D
42D 44C 40DD
42DD 44D 40DDD
44A 8AA 42B
44B 48A 42C
44C 48B 42D
44D 48C 42DD

Should I Definitely Opt for Sister Size Bras?

  1. Please remember that there are many reasons why a sizing bra doesn’t fit you. Note which attribute of your bra needs to be corrected in order to achieve the right fit. This will help you get a bra that fits the way it should. 
  2. It is also important to understand the physical changes in your body that may lead to a misfit. Puberty and pregnancy are stages when your regular bra would do no justice. So, trying sister sizes would be the ideal option here.
  3. Moreover, an ill-fitting bra can cause a lot of discomforts, neck and shoulder pain, and posture problems. So, it is better that you go for sister sizes rather than sticking with the same uncomfortable bra. 
  4. If you are still not satisfied with the sister sizing concept, we recommend you measure yourself again for the correct bra size to proceed with the shopping.