Sister Size Finder
Enter your current bra size to find sister sizes with the same cup volume.
Your Sister Sizes
These sizes have the same cup volume as your current size:
What sister sizes are
Sister sizes are bra sizes that hold the same cup volume on a different band. Going down one band and up one cup — 34C to 32D — keeps the cups the same size while making the band tighter. Enter the size you currently wear and this tool lists every sister size in both directions, which is what you try when a brand runs small or large.
Complete Sister Size Chart
All sizes in the same row have the same cup volume.
| Cup Volume | 28 | 30 | 32 | 34 | 36 | 38 | 40 | 42 | 44 |
|---|
How Sister Sizing Works
When you change band size, you must also change cup size to maintain the same cup volume:
- Going down a band size? Go up a cup size (e.g., 34C → 32D)
- Going up a band size? Go down a cup size (e.g., 34C → 36B)
This is useful when your calculated size isn't available, or when a brand runs large/small in the band.