Bra Size Conversion Chart
Convert band and cup sizes between US, UK, European, French, Italian and Australian systems.
Band sizes convert by measurement: a US or UK 34 is an EU 75, a French or Spanish 90 and an Australian 12. Cup letters agree up to D, after which the US and UK scales diverge and a US DDD is a UK E.
By Piero Nanni · Last checked
Matching rows are highlighted in the tables below.
A bra size is two separate measurements wearing one label. The number is the band, taken around the ribcage under the bust, and it converts cleanly because every system is measuring the same thing in different units. The letter is the cup, which is the difference between bust and band, and that is where the systems part company.
Up to a D cup, US and UK letters match. Above it they do not: the US adds letters as DD, DDD and then G, while the UK inserts DD, E, F, FF, G, GG. A US DDD and a UK E are the same cup. Getting that wrong by one letter is a full cup size, which is the most common fitting error after wearing the band too loose.
Band sizes
Underbust is the measurement taken snugly around the ribcage directly beneath the bust.
| Underbust (cm) | US / UK | EU / Germany | France / Spain | Italy | Australia |
|---|---|---|---|---|---|
| 63-67 | 30 | 65 | 80 | 0 | 8 |
| 68-72 | 32 | 70 | 85 | 1 | 10 |
| 73-77 | 34 | 75 | 90 | 2 | 12 |
| 78-82 | 36 | 80 | 95 | 3 | 14 |
| 83-87 | 38 | 85 | 100 | 4 | 16 |
| 88-92 | 40 | 90 | 105 | 5 | 18 |
| 93-97 | 42 | 95 | 110 | 6 | 20 |
| 98-102 | 44 | 100 | 115 | 7 | 22 |
Cup sizes
The cup is the difference between the bust measurement and the band measurement, so it is a difference, not an absolute size.
| Bust minus band (cm) | US | UK | EU / France |
|---|---|---|---|
| 10 | A | A | A |
| 12.5 | B | B | B |
| 15 | C | C | C |
| 17.5 | D | D | D |
| 20 | DD | DD | E |
| 22.5 | DDD / F | E | F |
| 25 | G | F | G |
| 27.5 | H | FF | H |
| 30 | I | G | I |
| 32.5 | J | GG | J |
Why the cup letter is not a fixed size
A cup is defined as a difference, not a volume. A 32D and a 38D have the same 17.5 cm bust-to-band difference but very different cup volumes, because the cup is drafted to sit on a larger band. That is what sister sizing means: a 34C and a 32D hold a similar volume, with the 32D on a tighter band.
It also means that going up a band size while keeping the letter makes the cup bigger, and dropping a band size while keeping the letter makes it smaller. If a band is too loose, go down a band and up a cup, not down a band alone.
Where US and UK letters diverge
Both systems agree through A, B, C and D. Above D the US uses DD, DDD (sometimes written F), then G, H, I. The UK uses DD, E, F, FF, G, GG, H, HH, inserting doubled letters as extra steps.
The practical mapping is US DD to UK DD, US DDD to UK E, US G to UK F, US H to UK FF. Buying a UK F expecting a US F gives a cup a full size too small, which is the usual reason a British brand appears to run small.
Measuring
Measure the underbust snugly, level and firm, standing upright. Measure the bust at the fullest point with the tape loose enough to lie flat. Subtract the band from the bust and read the cup from the difference.
Most fitting problems come from a band that is too large. The band carries the support, not the straps, so it should be firm enough that you can slide two fingers under it and no more. If the band rides up at the back, it is too big regardless of what the tape said.
Frequently Asked Questions
What is a 34C in EU sizes?
A 34C is an EU 75C, a French 90C and an Australian 12C.
Is a US DDD the same as a UK E?
Yes. The US and UK cup letters diverge above D, and US DDD equals UK E.
What is a 36B in French sizes?
A 36B is a French 95B. French band numbers run 15 above the EU number.
What is sister sizing?
Sizes with the same cup volume on different bands, such as 34C, 32D and 36B. Going down a band means going up a cup to keep the volume.
Why does my band ride up?
The band is too loose. Go down a band size and up a cup letter to keep the same cup volume.