40B bra size
40B means band 40 and cup B, with a 2 in difference between your bust and band; its bust range is 41.5 to 42.5 in.
US 40B · UK 40B
- Difference2 in5.1 cm
- Underbust, underbust method39 to 41 in99.06 to 104.14 cm
- Bust for this cup41.5 to 42.5 in105.41 to 107.95 cm
Each range includes its first figure and stops just short of its last.
Which measurements give a 40B
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 | 39 to 41 in | 99.06 to 104.14 cm | 41.5 to 42.5 in |
| Add-4 method | 34.5 to 36.5 in | 87.63 to 92.71 cm | 41.5 to 42.5 in |
| EU method, band 90 | 34.45 to 36.42 in | 87.5 to 92.5 cm | Cup read in cm |
Each range includes its first figure and stops just short of its last.
40B in six sizing systems
| System | Band | Cup | Size |
|---|---|---|---|
| US | 40 | B | 40B |
| UK | 40 | B | 40B |
| EU | 90 | B | 90B |
| FR/BE | 105 | B | 105B |
| AU/NZ | 18 | B | 18B |
| JP | 90 | C | 90C |
Bands and letters are label equivalents, not body measurements. JP letters vary by brand.
Sister sizes of 40B
A sister size moves the band one step and the cup one letter the other way.
- 2 bands down36D
- 1 band down38C
- 1 band up42A
- 2 bands up44AA
The cup for 40B represents the difference between your bust and band. A bust from 41.5 to 42.5 in leads to cup B under the underbust method and the add-4 method, though each method assigns a different underbust range to band 40.
The sister size 38C pairs a smaller band with a larger cup letter than 40B. The sister size 42A pairs a larger band with a smaller cup letter. The labels 36D and 44AA extend those steps in either direction. Published charts disagree on which band the same body receives: the underbust method and add-4 method use different underbust ranges for band 40.
The JP label for 40B is 90C, while the EU label is 90B. In JP, C comes one letter after B, and JP letters vary by brand. The table does not list 40B sister sizes two steps up in JP.
Questions
What does 40B mean?
40B is a band of 40 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 40B?
By the underbust method, an underbust of 39 to 41 in (99.06 to 104.14 cm) gives band 40, and a bust of 41.5 to 42.5 in gives this cup. By the add-4 method, band 40 comes from an underbust of 34.5 to 36.5 in. Each range includes its first figure and stops just short of its last.
What are the sister sizes of 40B?
The sister sizes of 40B are 36D, 38C, 42A and 44AA. Each step up in band takes the cup one letter down, and each step down takes it one letter up.