UK to US Bra Size Conversion
UK and US sizing agree on bands and on every cup through DD, then split: the UK inserts E, F, FF, G, GG where the US stacks DDD and jumps to G. The chart below aligns them by the inch difference each letter actually represents, which is the only conversion that survives past DD.
| Difference (in) | UK cup | US cup |
|---|---|---|
| <1 | AA | AA |
| 1 | A | A |
| 2 | B | B |
| 3 | C | C |
| 4 | D | D |
| 5 | DD | DD |
| 6 | E | DDD |
| 7 | F | G |
| 8 | FF | H |
| 9 | G | I |
| 10 | GG | J |
| 11 | H | K |
| 12 | HH | L |
The traps, named
The classic mistake is assuming letters align forever: shoppers order a US G expecting a UK G and receive two more inches of cup than intended, because UK inserted F and FF in between. The reverse trip bites too: UK FF wearers buying US brands need US G-ish territory, not F. Bands hold no traps, so when in doubt, keep your band number and convert the cup through the inch column above, or let the converter handle any size in one step.
Why bother with UK sizing at all as an American? Because the UK full-bust industry (Freya, Fantasie, Elomi, Bravissimo, Panache) cuts the deepest, best-engineered DD+ range in the world, and unlocking it takes exactly one conversion. The DD+ guide picks up from there.
Frequently asked questions
Written by the BraSizeConversion fit team. Last updated August 2026.