DD is where the letters stop matching. Up to D, every country names cups the same way. From DD on, each system has its own label, and that is where most sizing confusion begins.
What a DD cup measures
Measure snugly under the bust for the band, then loosely around the fullest part for the bust. A difference of about 5 inches is DD. A double letter is one full step of its own, not half a step: DD sits exactly one cup above D and one below the next letter.
DD cup measurements for every band
| Band | US size | Bust about | UK | EU | AU | Sister sizes |
|---|---|---|---|---|---|---|
| 28 | 28DD | 33 in (84 cm) | 28DD | 60E | 6DD | 30D |
| 30 | 30DD | 35 in (89 cm) | 30DD | 65E | 8DD | 28DDD, 32D |
| 32 | 32DD | 37 in (94 cm) | 32DD | 70E | 10DD | 30DDD, 34D |
| 34 | 34DD | 39 in (99 cm) | 34DD | 75E | 12DD | 32DDD, 36D |
| 36 | 36DD | 41 in (104 cm) | 36DD | 80E | 14DD | 34DDD, 38D |
| 38 | 38DD | 43 in (109 cm) | 38DD | 85E | 16DD | 36DDD, 40D |
| 40 | 40DD | 45 in (114 cm) | 40DD | 90E | 18DD | 38DDD, 42D |
| 42 | 42DD | 47 in (119 cm) | 42DD | 95E | 20DD | 40DDD, 44D |
| 44 | 44DD | 49 in (124 cm) | 44DD | 100E | 22DD | 42DDD |
The EU column is the one to watch. The European system uses single letters only, so the UK and US DD becomes an E there.
DD, E and DD/E: one cup, three names
- US and UK: DD is DD.
- Europe and France: the same cup is E. A 34DD is a 75E in Europe and a 90E in France.
- US tags that say DD/E: many American brands print both letters. They mean DD.
- UK E: in the UK and Australia, E is the next cup up, a 6-inch difference. A UK E is a US DDD.
So if a European bra in E fits, your UK or US size is DD. If a UK bra in E fits, you are one cup bigger than DD. The E cup page sorts out the labels above DD.
Is DD big?
It depends on the band. DD is the letter the often-quoted average US size, 34DD, uses, which surprises people who think of DD as unusual. A 30DD is a small bust on a narrow frame, while a 40DD is a large one. Like every letter, DD describes a difference, not a volume.
Sister sizes for DD
A 34DD holds about the same as a 32DDD (UK 32E) and a 36D. The chain continues to 30G (UK 30F) and 38C. If the cups fit but the band rides up, take the size one band down and one cup up. If the band digs in but the cups fit, go one band up and one cup down.
Finding DD bras
DD is stocked in most mainstream ranges, but the choice thins out quickly above it, especially in small bands like 28 and 30. Specialist ranges, many of them sized in UK letters, carry DD on every band with more cup shapes. When you shop internationally, check which system the brand uses before choosing E or DD.
Smaller: D cup. Larger: E cup.
Sources & method: sizing rules follow the standard band-and-cup system used by UK, US, AU and EU brands, checked against fitting guides from specialist retailers and fitting communities. How we work.