US DDD = US F = UK E. All three are a six-inch difference between bust and band. A UK F is a seven-inch difference, which American brands usually call G.
The same cup under four names
| Bust minus band | US | UK | EU |
|---|---|---|---|
| 5 in | DD | DD | E |
| 6 in | DDD or F | E | F |
| 7 in | G | F | G |
Why America has two names for it
American sizing extended the D cup by adding more Ds: D, DD, DDD. Some brands then carried on with DDDD, while others switched back to the alphabet and called the cup after DD an F. Both conventions are still in use, sometimes side by side on the same label as "DDD/F".
Where it goes wrong
- A UK shopper buying a US "F" expects a UK F and receives a cup one size smaller. A UK 34F is a US 34G.
- A US shopper buying a British brand in "F" receives a cup one size larger than they expected. A US 34F, or 34DDD, is a UK 34E.
- Not every US brand treats DDD and F as the same. A few make F a separate, larger step after DDD. If a size chart lists both as separate rows, count the steps above D to find your place.
How to be sure which you are looking at
Look at the other sizes on offer. If the list includes DDD, the sizing is American. If it includes FF or GG, it is British. If the band is 70, 75 or 80, it is European, and an F there is a UK E.
For the complete comparison of the two systems, see UK vs US bra sizes.
Frequently asked questions
What is a DDD cup in UK sizing?
An E. UK sizing has no DDD. The cup one size above DD is called E in the UK and DDD (or F) in the US.
Is DDD bigger than DD?
Yes, by one cup size. DDD is the American name for the six-inch cup, one inch more in the bust than a DD on the same band.
Is an E cup the same as a DDD?
A UK E is the same as a US DDD. A European E is different: it is one size smaller, equal to a UK and US DD.
Convert any US size to its UK label.
Open the US to UK converter →