DD cup size: what it means, and why it changes by band
DD is five inches of difference, one more than D. It is the last letter the UK and US labels share before their ladders split.
DD cup by band, in every system
| UK | US | EU | FR | AU | JP (approx.) |
|---|---|---|---|---|---|
| 30DD | 30DD | 65E | 80E | 8DD | F65 |
| 32DD | 32DD | 70E | 85E | 10DD | F70 |
| 34DD | 34DD | 75E | 90E | 12DD | F75 |
| 36DD | 36DD | 80E | 95E | 14DD | F80 |
| 38DD | 38DD | 85E | 100E | 16DD | F85 |
| 40DD | 40DD | 90E | 105E | 18DD | F90 |
"dd cup size" gets about 9,900 Google searches a month in the US (Google Ads data, 26 September 2026).
Sister sizes keep the DD cup's volume
Go down one band and up one letter, or up one band and down one letter, and the cup volume stays the same.
| UK | US | Compared with 32DD |
|---|---|---|
| 30E | 30DDD | Tighter band, 1 letter up |
| 32DD | 32DD | This size |
| 34D | 34D | Looser band, 1 letter down |
The full diagonal chart, with fit fixes for a band that rides up or digs in, is on the sister sizes page.
What people get wrong about the DD cup
"Double D" is not a separate scale
The name comes from the old convention of doubling letters once cups pass D. The UK and US both write it DD, five inches of difference, and agree on it exactly: it is the last letter both use before the UK goes to E and the US to DDD (Wikipedia, "Bra size").
Some US brands print this size as "E" instead
A handful of US brands label DD as "E" and DDD as "F" rather than using the double letters. That alias is one inch smaller than a true UK/international E cup; check a brand's own chart, or see the E cup page for the worked example.
DD looks different on every band
32DD, 34DD and 36DD hold the same cup letter but different tape measurements and different volumes; each has its own page with the underbust and bust figures that produce it.
Other sizes and tools
- Bra size calculatorMeasure your size with both methods shown
- Sister size chartThe full diagonal chart and fit fixes
- 32DDSister sizes, conversions and the measurements that land on 32DD
- 34DDSister sizes, conversions and the measurements that land on 34DD
- 36DDSister sizes, conversions and the measurements that land on 36DD
- B cupWhat the letter means, by band
- D cupWhat the letter means, by band
- E cupWhat the letter means, by band
Sources
Each source was opened and checked on 25 September 2026. Where sources disagree, the page says so instead of picking one silently.
- Wikipedia, "Bra size": UK and US cup ladders, the +4 method, EN 13402 and JIS cup steps
- White J, Scurr J. Evaluation of professional bra fitting criteria for bra selection and fitting in the UK. Ergonomics 2012;55(6):704-711: 45 women; the traditional method overestimated band and underestimated cup