A Cup
1 inch (2.5 cm) difference
Smallest standard cup size, ideal for petite frames
Common sizes: 28A, 30A, 32A, 34A
B Cup
2 inches (5 cm) difference
Small cup size, very common for smaller builds
Common sizes: 30B, 32B, 34B, 36B
C Cup
3 inches (7.5 cm) difference
Medium cup size, one of the most common sizes
Common sizes: 32C, 34C, 36C, 38C
D Cup
4 inches (10 cm) difference
Fuller cup size, requires good support
Common sizes: 32D, 34D, 36D, 38D
DD Cup
5 inches (12.5 cm) difference
Full cup size, also known as E in some systems
Common sizes: 32DD, 34DD, 36DD, 38DD
E Cup
6 inches (15 cm) difference
Large cup size requiring structured support
Common sizes: 32E, 34E, 36E
F Cup
7 inches (17.5 cm) difference
Full bust requiring specialty bras
Common sizes: 32F, 34F, 36F
G Cup
8 inches (20 cm) difference
Very full bust, specialty sizing required
Common sizes: 32G, 34G, 36G
| Cup | Bust-Band Difference | Approx. Volume (34 band) | UK Equivalent |
|---|---|---|---|
| A | 1 inch (2.5 cm) | ~100-150 ml | A |
| B | 2 inches (5 cm) | ~200-250 ml | B |
| C | 3 inches (7.5 cm) | ~300-400 ml | C |
| D | 4 inches (10 cm) | ~450-550 ml | D |
| DD | 5 inches (12.5 cm) | ~600-750 ml | DD/E |
| E | 6 inches (15 cm) | ~800-950 ml | E |
| F | 7 inches (17.5 cm) | ~1000-1200 ml | F |
| G | 8 inches (20 cm) | ~1300-1500 ml | G |
How are bra cup sizes determined?
Cup size is determined by the difference between your bust measurement and your underbust (band) measurement. Each inch of difference typically corresponds to one cup size: 1 inch = A cup, 2 inches = B cup, 3 inches = C cup, and so on.
What is the most common cup size?
The most commonly purchased cup sizes vary by country, but globally, C and D cups are among the most common. However, studies suggest many women wear the wrong size, often underestimating their cup size.
Do cup sizes change with band size?
Yes! Cup volume is relative to band size. A 32D has smaller cups than a 38D, even though both are 'D cups'. This is why sister sizing exists - a 32D, 34C, and 36B all have similar cup volumes.
What does DD mean? Is it the same as E?
DD (double D) is primarily used in US and UK sizing and equals 5 inches of difference. In EU sizing, this is often labeled as E. However, UK E cup is larger than DD (6 inches difference).
How do I know if I need a larger cup size?
Signs you need a larger cup: spillage over the top or sides, underwire sitting on breast tissue, cups that wrinkle or gap, or the center gore not lying flat against your chest.