Question 1

What are sister sizes in bras?

Accepted Answer

Sister sizes are groups of bra sizes that share the same cup volume but with different band sizes. When you go up a band size, you go down a cup size (and vice versa). For example, 32D, 34C, and 36B are sister sizes — they all hold the same cup volume.

Question 2

When should I try a sister size?

Accepted Answer

Try a sister size when your current bra band feels too tight or too loose, but the cups fit well. If the band is too tight, go up one band size and down one cup. If it's too loose, go down one band and up one cup.

Question 3

Do sister sizes fit exactly the same?

Accepted Answer

Sister sizes maintain the same cup volume, but the fit will differ slightly. A tighter band with a larger cup will feel more supported. A looser band with a smaller cup will feel more relaxed. The overall coverage and shape of the cup may also differ.

Sister Size Bra Chart

Find Your Sister Sizes

Sister Sizes

Common Sister Size Groups

Frequently Asked Questions

Sister Sizes (same cup volume)
30D32C34B36A
30DD32D34C36B
32DD34D36C38B
34DD36D38C40B
36DD38D40C42B