Cup Size Chart
Every cup letter is a difference in inches between bust and band, and the same letter holds more on a bigger band. See it, then read the number behind every letter in every system.
See every band and cup drawn to scale on the chart with pictures →
Cup volume changes with the band
How cup sizes are calculated
Bust minus band, rounded to the nearest inch. Each inch is one cup letter.
A cup size isn't a fixed volume. It's a relationship: how much larger the fullest part of the bust is than the ribcage the bra sits on. One inch of difference is an A cup, two is a B, three is a C, and so on.
That's why the same letter means different volumes on different bands. A 32C, 34C and 36C are three different cup volumes: each is exactly three inches larger than its own band, and those bands are two inches apart.
Key takeaway: read cup and band together, always. A cup letter on its own tells you nothing about volume.
Cup size chart: inch difference to cup letter
| Bust − band | US cup | UK cup | EU cup | ≈ cm |
|---|---|---|---|---|
| 0″ | AA | AA | AA | 0 |
| 1″ | A | A | A | 2.5 |
| 2″ | B | B | B | 5 |
| 3″ | C | C | C | 7.5 |
| 4″ | D | D | D | 10 |
| 5″ | DD | DD | E | 12.5 |
| 6″ | DDD | E | F | 15 |
| 7″ | G | F | G | 17.5 |
| 8″ | H | FF | H | 20 |
| 9″ | I | G | I | 23 |
| 10″ | J | GG | J | 25 |
| 11″ | K | H | K | 28 |
Some US brands write DDD as F and skip the triple-D. Check the brand's own chart above a D cup.
Where the systems split
The US repeats the D up to three times, then jumps to G. Some US brands substitute F for DDD.
The UK doubles alternate letters (DD, then E, F, FF, G, GG) giving finer steps at larger cups. UK sizing is common in full-bust brands.
Continental Europe just continues the alphabet, one letter per inch. The simplest system to read.
Same cup, three names: a US DDD, a UK E and an EU F all describe a six-inch difference. Use the size converter to translate exactly.
Bust measurement for every band and cup (US)
Find your band row and read across: each cell is the bust measurement that produces that cup on that band. Every cell links to the size's own guide.
| Band (underbust) | A | B | C | D | DD | DDD | G | H |
|---|---|---|---|---|---|---|---|---|
| 28 (27″) | 29″ | 30″ | 31″ | 32″ | 33″ | 34″ | 35″ | 36″ |
| 30 (29″) | 31″ | 32″ | 33″ | 34″ | 35″ | 36″ | 37″ | 38″ |
| 32 (31″) | 33″ | 34″ | 35″ | 36″ | 37″ | 38″ | 39″ | 40″ |
| 34 (33″) | 35″ | 36″ | 37″ | 38″ | 39″ | 40″ | 41″ | 42″ |
| 36 (35″) | 37″ | 38″ | 39″ | 40″ | 41″ | 42″ | 43″ | 44″ |
| 38 (37″) | 39″ | 40″ | 41″ | 42″ | 43″ | 44″ | 45″ | 46″ |
| 40 (39″) | 41″ | 42″ | 43″ | 44″ | 45″ | 46″ | 47″ | 48″ |
| 42 (41″) | 43″ | 44″ | 45″ | 46″ | 47″ | 48″ | 49″ | 50″ |
| 44 (43″) | 45″ | 46″ | 47″ | 48″ | 49″ | 50″ | 51″ | 52″ |
Read diagonally down-left for sister sizes: 34C, 32D and 30DD all sit on the 37″ bust diagonal.
Cup sizes: answered
What cup size is a 3 inch difference?
A three-inch difference between bust and band is a C cup in US, UK and EU sizing.
Is a D cup big?
Not on its own. A 30D holds roughly the same volume as a 34B. Whether a D cup is 'big' depends entirely on the band it's paired with. Use the visualizer above to compare.
What comes after DD?
In the US: DDD (sometimes written F), then G. In the UK: E, then F, FF, G. In the EU: F, then G. They're the same cup, named differently.
Is DDD the same as F?
In US sizing many brands use F as an alternative name for DDD, so yes within US sizing. But a UK F is one step larger (a seven-inch difference), so don't assume F means the same thing across countries.
Why do cup sizes change with band size?
Because a cup letter measures the difference between bust and band, not an absolute volume. A bigger band with the same letter means a bigger bust measurement and a larger cup.
What is the smallest bra cup size?
AA is the smallest standard cup, for a bust measurement equal to or up to about half an inch above the band. Some brands also make AAA.
How many cm is one cup size?
About 2.5 cm of bust-minus-band difference per cup letter: the metric equivalent of one inch.
Opens HauteFlair’s own hub page; use your measured size there. HauteFlair is owned by the same company as Brasize.ai; that relationship never changes the sizing math, charts, or fit advice on this page. How this site makes money.