Bra Size Conversion Chart: US, UK, EU, French, AU, Japan

A bra size conversion chart translates one country's label into another's. The band converts by a fixed rule: a US or UK 34 is a European 75, a French, Belgian or Spanish 90, an Australian 12 and a Japanese 75. The cups are where people get lost. A, B, C and D mostly match everywhere, then the systems split at DD: a UK DD is a European E, and a UK E is a US DDD.

The two charts below handle each half of the size separately, which is the only way the conversion works.

Band sizes: inches, centimeters and dress sizes

Every band number names the same thing, the underbust, in a different unit. The US and UK count in inches, in 2-inch steps. The European standard EN 13402 labels a bra with the underbust girth in centimeters, rounded to the nearest 5 cm, so a 34 band becomes 75. France, Belgium and Spain use the European cups but add 15 to the band, which is why a French house such as Chantelle can label the same bra 90. Australia and New Zealand number bands like dress sizes, so 34 is a 12 and 36 is a 14. Japan uses centimeters in 5 cm steps, with each number covering 2.5 cm either side. Italy counts in plain ordinal sizes, and the numbering is not settled: Intimissimi's own chart makes a 70 cm band (US and UK 32) a size 1, while Wikipedia's table starts size I at 65 cm (US and UK 30). Read the Italian maker's chart rather than a general one.

How the DD, E and F cup letters drift apart

A cup letter stands for the difference between the bust and the underbust, but each system steps at its own rate. UK cups go up one letter per inch, which is 2.54 cm. European cups go up one letter per 2 cm: EN 13402 sets an A at 12 to 14 cm of difference, a B at 14 to 16 cm, and so on to an H at 26 to 28 cm. Over ten cups the UK scale covers 25.4 cm of difference and the European one 20 cm, so the gap widens as the cups grow.

The alphabets differ too. After D, British brands add doubled letters: DD, E, F, FF, G, GG, H, HH, J, JJ, K. Europe runs single letters: D, E, F, G, H. American labels are the least consistent. Some follow DD with DDD and then G, while others print DD/E and DDD/F on the same tag. That is why a US 34DDD and a UK 34E are normally the same bra.

Above FF, the American letters keep running one step ahead in Wikipedia's comparison of national systems (UK G is a US I, UK GG a US J) but disagree on the European letter, so a UK G or larger needs the maker's own table.

Australia has no single rule either. Wikipedia's survey of national systems says Australian labels follow the UK up to DD and switch to European letters after it, while an Australian retailer reading Chantelle's international guide maps a UK DD to an Australian E. The band is safe to convert; the cup on an Australian label should be checked against that brand's chart.

Japan's 2.5 cm cups and the B75 label

Japanese sizing measures the same difference but in 2.5 cm steps. The cup scale starts with AA at 7.5 cm, then A at 10 cm, B at 12.5 cm and so on, up to an I at about 30 cm. The label usually puts the cup first, so a Japanese B75 is a B cup on a 75 cm band. The sizes come from the JIS L4006 standard, introduced in 1998, and makers such as Wacoal print them that way.

Set side by side, the two metric systems give different letters for the same body:

Through the middle of the range the Japanese letter reads one cup larger, then the two meet around F.

Why the cup letters began in America

Letter cups are younger than the bra itself. In October 1932 S.H. Camp and Company became the first maker to sell A, B, C and D cups, though its letters described how pendulous the breasts were, not their volume. In 1935 Warner's launched its Alphabet Bra, with letters tied to volume, and that is the system the American letters descend from. Britain held out: it did not adopt American cups in 1933 and resisted cup sizes on its own products until 1948. Europe later went its own way, with cups counted in centimeters.

Reading a foreign label without guessing

Convert the band and the cup separately, using the column for the country on the label, not the country where the bra was sold. A UK brand sold in New York still sizes in UK letters, and FF or GG on a tag points to the UK alphabet, which American and European charts do not use. Treat every chart as a starting point: Braforme, a retailer that publishes a four-column conversion, warns that equivalents vary from brand to brand. The cut changes the fit as well, and a plunge and a full cup in one size sit differently; our complete bra type guide covers the styles.

The one number that never needs converting is the tape measure itself. A 75 cm underbust is 75 cm in Lyon, Leeds and Osaka.

Last updated November 7, 2026

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