Band size = rounded underbust (add 4" for even, 5" for odd in US sizing). Cup = full bust minus band, where each inch = one cup letter (A, B, C…).
Your bra size
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Sister sizes explained
Cups hold the same volume across sister sizes — as the band gets smaller, the cup letter grows.
Same cup volume
32C, 34B and 36A all hold roughly the same breast volume. If 34B feels tight, try 36A.
Band too loose?
Go down a band and up a cup: 34C → 32D. The band does 80% of the support work.
Band too tight?
Go up a band and down a cup: 32D → 34C. Use the loosest hook for a new bra.
Fit check signals
A good fit goes beyond the numbers — check these on every bra:
- • Band level — the band should sit horizontal all the way around, not riding up the back.
- • Centre gore — the wire bridge should lie flat against your sternum.
- • No spillage — breast tissue should not bulge over the cup tops or under the armpits.
- • Two fingers — you should fit two fingers under the band; no more, no less.
More sizing tools
Get your ring, dress and shoe sizes right too with our full styling suite.
Ring Size Calculator