Type your underbust and bust measurements and see the corresponding bra size in BR, EU, US and UK — with band and cup charts on screen.
A bra size is two numbers joined as one. The band — the number, like 40 or 80 — comes from the underbust circumference and determines the frame of the bra. The cup — the letter, like B or D — comes from the difference between the bust and the underbust, and determines how much room the bra needs for the breast itself. Neither number means anything on its own: a D cup on a 36 band holds less volume than a D cup on a 44 band, because the cup scales with the band. That is why "I wear a D" is incomplete information, and why sister sizing — going up a band and down a cup, or the reverse — works.
The Brazilian market inherited the British inch-based band numbers: 36, 38, 40, 42 and so on, each roughly five centimetres apart. The European system uses centimetres directly: 70, 75, 80, 85. The US and UK share the same band numbers as Brazil, so a BR 40 is a US 36 and an EU 80 — the correspondence is stable. Cup letters are where the trouble starts. Through D, the four systems agree. Above D, the US doubles up (DD, DDD), the UK inserts its own sequence (DD, E, F, FF, G), and the EU counts straight through (E, F, G). A US DDD is a UK E is an EU F — and a Brazilian brand could use any of the three conventions, because there is no ABNT standard for bras.
This converter takes two centimetre measurements, maps the underbust to the closest band and the bust-to-underbust difference to the closest cup, and shows all four systems at once. Both charts — the band chart with underbust ranges and the cup chart with difference ranges — are on screen, and they are assembled from the correspondences in common use across Brazilian retail. Nothing is standardised, and every brand cuts differently: the real test is always the fitting room. Your measurements stay in your browser and the page works offline.
Band: the underbust measurement in centimetres falls in a range that maps to a BR/EU/US number. Cup: difference = bust − underbust. Each 3 cm increment maps to the next cup letter. BR 40C means an underbust of 68–72 cm and a difference of 13–15 cm.
Because the cup is relative to the band. A 36D holds much less volume than a 46D — the letter describes the difference between bust and underbust, not an absolute size. A D cup on a small frame looks very different from a D cup on a large one.
No. The converter runs entirely in JavaScript on your device. Nothing is uploaded, stored or logged.
The three systems diverge in how they name cups past D. The US uses DD then DDD, the UK uses DD then E, and the EU skips DD entirely and goes D, E, F. The bust-to-underbust difference is the same — only the label changes. This page shows all three.
Going up one band and down one cup, or the reverse, to keep roughly the same cup volume. A 40C, a 42B and a 38D are sister sizes: the volume of the cup is similar, but the band length changes. It is useful when a brand runs tight or loose in the band.
No. There is no ABNT standard for bras. The numbers come from the British inch-based system, and different brands use different cup conventions — some follow the US (DD, DDD), others the UK (DD, E) or the EU (E, F). The only way to know is checking the brand chart.
For the bust measurement, wear a non-padded bra or no bra — padding adds to the measurement and throws the cup off. For the underbust, it makes no difference because the tape sits below the bust.
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