Cherry SizeCalculator › All bra sizes, size by size › 30B
30B bra size — conversions, sister sizes & fit
A 30B fits an underbust of about 63–67 cm with a bust 11–14 cm larger than the band. Here is everything that label actually means — and how to check it really fits you.
Your bra size
30B US
Which measurements give 30B?
| cm | |
|---|---|
| Underbust (snug) | 63–67 |
| Bust (fullest point) | 74–81 |
| Difference (cup volume) | 11–14 |
Between two sizes? Measurements near the edges of these ranges can also fit the neighbouring size — check the sister sizes below and, in doubt, trust the fit checks from our measuring guide.
Sister sizes of 30B
28C and 32A hold the same cup volume as 30B with a tighter or looser band. If the band of a 30B rides up, try 28C; if it digs in, try 32A.
Small bands with small cups are genuinely underserved on the high street: many mainstream brands start at a 65 or even 70 band, so a lot of what fits you sits in petite-focused or Asian-market lines. Avoid the classic trap of taking a bigger band to find a cup that exists — a loose band gives no support. Look for brands whose range is confirmed to start at your band, and use the sister size only as a fitting-room fallback.
Who makes 30B? 215 of the 632 brands in the Cherry Size catalogue are confirmed to carry 30B in their standard range. But each of them cuts it differently — the app tells you the exact size to try at every one of them, from your own measurements.
See 30B brand by brand30B in questions
What is 30B in European sizing?
A 30B corresponds to 65B in European sizing and 80B in French/Spanish sizing. The cup volume is identical — only the band numbering changes between systems.
Is 30B big or small?
It is one of the smaller sizes: a petite band with a shallow cup. Cup letters mean nothing alone: a cup only has a volume relative to its band, which is why 28C and 32A hold exactly the same volume as 30B.
My 30B doesn't fit — what should I try?
If the band rides up or feels loose, go to 28C. If the band digs in while the cup is fine, go to 32A. If the cup overflows, try one cup up in the same band; if it wrinkles empty, one cup down. Two minutes with the calculator confirms it.
Nearby sizes
Your size, everywhere you shop
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