30B bra size
30B pairs band 30 with cup B; a 2 in difference between bust and band puts your bust at 31.5 to 32.5 in for this cup.
US 30B · UK 30B
- Difference2 in5.1 cm
- Underbust, underbust method29 to 31 in73.66 to 78.74 cm
- Bust for this cup31.5 to 32.5 in80.01 to 82.55 cm
Each range includes its first figure and stops just short of its last.
Which measurements give a 30B
The label is a band and a cup, not a body measurement. Each of the three published rules turns the same label into different measurements.
| Method | Underbust (in) | Underbust (cm) | Bust (in) |
|---|---|---|---|
| Underbust method | 29 to 31 in | 73.66 to 78.74 cm | 31.5 to 32.5 in |
| Add-4 method | 24.5 to 26.5 in | 62.23 to 67.31 cm | 31.5 to 32.5 in |
| EU method, band 65 | 24.61 to 26.57 in | 62.5 to 67.5 cm | Cup read in cm |
Each range includes its first figure and stops just short of its last.
30B in six sizing systems
| System | Band | Cup | Size |
|---|---|---|---|
| US | 30 | B | 30B |
| UK | 30 | B | 30B |
| EU | 65 | B | 65B |
| FR/BE | 80 | B | 80B |
| AU/NZ | 8 | B | 8B |
| JP | 65 | C | 65C |
Bands and letters are label equivalents, not body measurements. JP letters vary by brand.
Sister sizes of 30B
A sister size moves the band one step and the cup one letter the other way.
- 1 band down28C
- 1 band up32A
- 2 bands up34AA
On band 30, the 31.5 to 32.5 in bust span corresponds to cup B. The cup represents the difference between bust and band, rounded to whole inches, so this label connects a band number with a measurement relationship.
The 30B label stays 30B on US and UK tags, but the same size appears as 65B under the EU method. FR/BE uses 80B, AU/NZ uses 8B, and JP uses 65C. Published charts disagree on how a body maps to a band: the underbust method uses the underbust itself, while the add-4 method and EU method use different approaches.
The JP label for 30B uses cup C, one letter after the EU cup B, and one chart reports that JP letters vary by brand. Its sister size 28C pairs a smaller band with a larger cup, while 32A pairs a larger band with a smaller cup. The table also includes 34AA, but does not list a JP counterpart for it.
Questions
What does 30B mean?
30B is a band of 30 with a cup that stands for a difference of 2 in (5.1 cm) between bust and band in US sizing.
What measurements give a 30B?
By the underbust method, an underbust of 29 to 31 in (73.66 to 78.74 cm) gives band 30, and a bust of 31.5 to 32.5 in gives this cup. By the add-4 method, band 30 comes from an underbust of 24.5 to 26.5 in. Each range includes its first figure and stops just short of its last.
What are the sister sizes of 30B?
The sister sizes of 30B are 28C, 32A and 34AA. Each step up in band takes the cup one letter down, and each step down takes it one letter up.