Sister Sizes Explained
Sister sizes have the same cup volume but different band sizes. They're the secret weapon for finding bras that actually fit comfortably.
The Core Concept
When you go up a band size, you go down a cup size to keep the same cup volume. And vice versa.
All three sizes have the exact same cup volume.
Interactive Sister Size Tool
Sister Sizes: The Secret to Perfect Fit
Same cup volume, different band sizes. Game-changer for finding comfort.
Your size: 34D
Band feels too loose?
Try a sister size down - smaller band, larger cup. The band will be snugger, but cup volume stays the same.
Band feels too tight?
Try a sister size up - larger band, smaller cup. More breathing room, same cup volume.
Pro Tips
- • Band provides 80% of support - it should be snug but comfortable
- • You should be able to fit two fingers under the band
- • Cups that gap? Try sister size down. Spillage? Try sister size up.
- • Different brands fit differently - sister sizes help you find the right one
When to Try a Sister Size
Try a Sister Size DOWN when:
- • Your band rides up your back
- • You're on the tightest hook from day one
- • The band feels loose even when new
- • You need more support
Example: 34D → 32DD
Try a Sister Size UP when:
- • Your band feels too tight
- • The band digs in or leaves marks
- • You can't comfortably fit two fingers under the band
- • You want more breathing room
Example: 34D → 36C
Sister Size Chart
| Sister Size Down | Your Size | Sister Size Up |
|---|---|---|
| 30DD | 32D | 34C |
| 32D | 34C | 36B |
| 34E | 36DD | 38D |
| 36C | 38B | 40A |
| 38DD | 40D | 42C |
Pro Tips
Things to remember about sister sizes:
- •The band provides 80% of support. A well-fitting band is crucial - sister sizes help you find it.
- •The two-finger test: You should be able to fit two fingers under your band. No more, no less.
- •Cup gapping? Before going down a cup size, try a sister size down. The tighter band may solve the gap.
- •Cup spillage? Before going up a cup, try a sister size down. Sometimes a too-loose band causes spillage.
- •Different brands fit differently. You might be 34D in one brand and 32DD in another.
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