40A bra size
40A names band 40 and cup A: its cup marks a 1 in difference between your bust and band, and the listed bust range of 40.5 to 41.5 in is the range associated with that cup label on this page.
US 40A · UK 40A
- Difference1 in2.5 cm
- Underbust, underbust method39 to 41 in99.06 to 104.14 cm
- Bust for this cup40.5 to 41.5 in102.87 to 105.41 cm
Each range includes its first figure and stops just short of its last.
Which measurements give a 40A
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 | 40.5 to 41.5 in |
| Add-4 method | 34.5 to 36.5 in | 87.63 to 92.71 cm | 40.5 to 41.5 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.
40A in six sizing systems
| System | Band | Cup | Size |
|---|---|---|---|
| US | 40 | A | 40A |
| UK | 40 | A | 40A |
| EU | 90 | A | 90A |
| FR/BE | 105 | A | 105A |
| AU/NZ | 18 | A | 18A |
| JP | 90 | Not listed | Not listed |
Bands and letters are label equivalents, not body measurements. JP letters vary by brand.
Sister sizes of 40A
A sister size moves the band one step and the cup one letter the other way.
- 2 bands down36C
- 1 band down38B
- 1 band up42AA
For 40A, cup A covers a bust range of 40.5 to 41.5 in on band 40; both the underbust method and add-4 method assign that cup within this range.
The 40A tag appears unchanged in US and UK, but the same label becomes 90A in EU, 105A in FR/BE, and 18A in AU/NZ. Published charts disagree about which band follows from your underbust: the underbust method and add-4 method give band 40 from separate ranges, while the EU method assigns band 90. For 40A, the cup letter stays A across those listed systems.
JP has no cup letter listed for 40A, and its chart directs you to check the brand. The sister size 42AA raises the band and lowers the cup; 38B lowers the band and raises the cup. The JP table does not list 42AA.
Questions
What does 40A mean?
40A is a band of 40 with a cup that stands for a difference of 1 in (2.5 cm) between bust and band in US sizing.
What measurements give a 40A?
By the underbust method, an underbust of 39 to 41 in (99.06 to 104.14 cm) gives band 40, and a bust of 40.5 to 41.5 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 40A?
The sister sizes of 40A are 36C, 38B and 42AA. Each step up in band takes the cup one letter down, and each step down takes it one letter up.