You know your size. You order from a British brand, or a European one, and what arrives fits nothing like what you expected.
The band was never the problem. Bands translate cleanly. It is the cup letters that diverge, and they diverge in a way that catches out almost everyone shopping across markets for the first time.
Band size conversion
US and UK bands are measured in inches and use the same numbers. EU bands are measured in centimetres, which is why the numbers look completely different but mean the same thing.
| US | UK | EU | FR / ES | AU |
|---|---|---|---|---|
| 30 | 30 | 65 | 80 | 8 |
| 32 | 32 | 70 | 85 | 10 |
| 34 | 34 | 75 | 90 | 12 |
| 36 | 36 | 80 | 95 | 14 |
| 38 | 38 | 85 | 100 | 16 |
| 40 | 40 | 90 | 105 | 18 |
| 42 | 42 | 95 | 110 | 20 |
| 44 | 44 | 100 | 115 | 22 |
The rule is simple: EU band equals US band multiplied by roughly 2.5, then rounded to the nearest 5. French and Spanish sizing adds 15 to the EU number.
Cup size conversion
This is where it goes wrong. US sizing repeats the D, running D, DD, DDD. UK sizing introduces new letters instead, running D, DD, E, F, FF, G.
The result: a US DDD and a UK E are the same cup. Not close. Identical.
| US | UK | EU |
|---|---|---|
| A | A | A |
| B | B | B |
| C | C | C |
| D | D | D |
| DD | DD | E |
| DDD / F | E | F |
| G | F | G |
| H | FF | H |
| I | G | I |
| J | GG | J |
Notice that EU cups line up with US cups everywhere except the DD point, where the EU switches to E and stays one step ahead from there on.
Worked examples
- US 34DD equals UK 34DD and EU 75E
- US 36DDD equals UK 36E and EU 80F
- UK 32F equals US 32G and EU 70G
- EU 85D equals US 38D and UK 38D
Why the same size still fits differently
Even with a correct conversion, two bras labelled the same can fit differently. Three reasons, in order of how often they matter.
Vanity sizing on the band
Some brands run bands loose so the first try-on feels comfortable. It feels good in the fitting room and rides up within a month. If a band feels immediately relaxed on the loosest hook, it is too big.
Cup shape, not cup volume
A balconette, a plunge and a full cup can all hold the same volume and fit three different bodies well. If your size is right but something is off, the shape is the variable to change, not the letter.
Sister sizing
Cup volume is tied to the band. A 34C and a 36B hold roughly the same amount. Down a band means up a cup, and up a band means down a cup. Useful when your size is sold out, and useful for closing the gap when a brand runs small.
- 34D sister sizes: 32DD and 36C
- 36DD sister sizes: 34DDD and 38D
Bras that make the conversion easier
Strapless Mesh Underwire Balconette Bra is sized in true band and cup rather than S to XL, running to a G cup. When you have done the conversion, you can order the exact number.
Seamless Unlined Balconette Bra is unlined, which means less padding between you and the cup and a more honest fit read on the first wear.
Flex Size Extender covers the case where you converted correctly but the brand simply runs tight on the band. Cheaper than a return.
Shop Bras, Plus Size Bras and Full Support Bras.
Frequently asked questions
Are bra sizes universal?
No. Band numbers are consistent between US and UK but change entirely in the EU, and cup letters diverge from DD upward. A single body can wear three differently labelled sizes across three markets and be correctly fitted in all of them.
Are bra sizes in inches or centimetres?
US, UK and Australian sizing is based on inches. EU, French and Spanish sizing is based on centimetres.
What comes after DDD in US sizing?
G, then H, then I. The US skips E and F as standalone letters in most brands, which is exactly why the UK equivalents look so far apart on paper.
Is a UK E the same as a US E?
No. A UK E equals a US DDD. Getting this one wrong is the most common cross-market ordering mistake there is.
What is my EU size if I am a US 36C?
EU 80C. The band converts from 36 to 80, and the C cup carries over unchanged because the divergence only begins at DD.
How do I find my size in the first place?
Two measurements and one subtraction. See our guide to measuring your bra size at home, then check the result against the seven signs of a wrong size.
