Sister Size Calculator
Find your perfect fit with equivalent bra sizes. Sister sizes have the same cup volume but different band sizes, giving you more options for comfort and fit.
Find Sister Sizes
Understanding Sister Sizes
What Are Sister Sizes?
Sister sizes are bra sizes that have the same cup volume but different band sizes. The cup size adjusts proportionally to maintain the same breast volume coverage.
Example:
34C = 32D = 36B
All have the same cup volume!
The Sister Size Rule
📏 As the band gets smaller (-2), the cup gets larger (+1 letter)
📏 As the band gets larger (+2), the cup gets smaller (-1 letter)
Common Sister Size Chains
| Chain 1 | Chain 2 | Chain 3 |
|---|---|---|
| 30C = 32B = 34A | 32D = 34C = 36B | 34DD = 36D = 38C |
| 36DDD = 38DD = 40D | 38G = 40DDD = 42DD | 40H = 42G = 44DDD |
Shopping Tips
- Always try sister sizes when your usual size is unavailable
- Different brands may fit differently even in sister sizes
- Consider your comfort preference for band tightness
- Sister sizes are especially helpful for hard-to-find sizes
Complete Sister Size Chart
| Smaller Band | Your Size | Larger Band |
|---|---|---|
| 28B | 30A | 32AA |
| 28C | 30B | 32A |
| 28D | 30C | 32B |
| 30D | 32C | 34B |
| 30DD | 32D | 34C |
| 32DD | 34D | 36C |
| 32DDD | 34DD | 36D |
| 34DDD | 36DD | 38D |
| 34G | 36DDD | 38DD |
| 36G | 38DDD | 40DD |
| 38G | 40DDD | 42DD |
| 38H | 40G | 42DDD |
| 40H | 42G | 44DDD |
All sizes in each row have the same cup volume, just different band sizes.