International Bra Size Conversion Reference (UK / US / EU / FR + Sister Sizes)
Usage Guide
The short answer: bra sizing systems differ in labels, not bodies. A UK/US 34 band is an EU 75 and an FR/ES/BE 90 (US bands match UK; EU climbs in steps of five from 60 at UK 28; the French number is the EU number plus fifteen). The cup letter is the bust-minus-band difference at one letter per inch — a three-inch difference is a C — and sister sizes (34C, 32D, 36B) hold the same cup volume on different bands. Every cell below is deterministic arithmetic you can verify against any retailer's size chart.
About this reference
This page is a conversion reference, not a survey: it contains no estimates, no statistics and no prices — only the arithmetic behind published industry sizing conventions, the same rules our bra size calculator applies. Two honest caveats. First, the tables convert labels between systems; brands can still instruct different measuring methods to arrive at your starting band number, so when a brand publishes its own chart, that chart wins. Second, cup naming genuinely diverges between the UK and US ladders after DD — we show the split explicitly instead of papering over it. Last reviewed 2026-07-10.
Band size conversion (UK / US / EU / FR-ES-BE)
UK and US bands share the same even-numbered inch ladder. EU bands step by five starting at 60 (= UK 28); the French / Spanish / Belgian number is the EU number plus fifteen.
| UK band | US band | EU band | FR / ES / BE band |
|---|---|---|---|
| 28 | 28 | 60 | 75 |
| 30 | 30 | 65 | 80 |
| 32 | 32 | 70 | 85 |
| 34 | 34 | 75 | 90 |
| 36 | 36 | 80 | 95 |
| 38 | 38 | 85 | 100 |
| 40 | 40 | 90 | 105 |
| 42 | 42 | 95 | 110 |
| 44 | 44 | 100 | 115 |
Cup letter derivation (bust − band difference)
Measure the fullest part of the bust and subtract the band measurement: each inch of difference is one cup step. UK and US agree through D, then the ladders split — UK continues DD, E, F, FF, G while US continues DD, DDD/F, G, H — so the same bust can carry a different letter on each side of the Atlantic.
| Bust − band (inches) | US cup | UK cup |
|---|---|---|
| <1 | AA | AA |
| 1 | A | A |
| 2 | B | B |
| 3 | C | C |
| 4 | D | D |
| 5 | DD (some brands: E) | DD |
| 6 | DDD / F | E |
| 7 | G | F |
| 8 | H | FF |
Sister sizes
Go down one band size and up one cup letter (or up one band and down one cup) and the cup volume stays effectively the same — only the band length changes. That is why a 34C, a 32D and a 36B hold the same bust on different ribcages, and why a sold-out size usually has a sister size worth trying.
| Your size | Band down (−2 band, +1 cup) | Band up (+2 band, −1 cup) |
|---|---|---|
| 32B | 30C | 34A |
| 32C | 30D | 34B |
| 34B | 32C | 36A |
| 34C | 32D | 36B |
| 34D | 32DD | 36C |
| 36C | 34D | 38B |
| 36D | 34DD | 38C |
| 38C | 36D | 40B |
Shapewear sizing: a dress-size mapping
Unlike bras, most shapewear sells on the XS–3XL ladder, and those letters are effectively a mapping of dress sizes. The mapping below is the common convention, but it is the one table on this page that is not universal: cut, target compression and inclusive size runs shift it per brand — treat it as a starting point and defer to the brand's own chart every time.
| Shapewear size | Typical US dress size (varies by brand) |
|---|---|
| XS | 0-2 |
| S | 4-6 |
| M | 8-10 |
| L | 12-14 |
| XL | 16-18 |
| 2XL | 20-22 |
| 3XL | 24-26 |
Formulas (reproducibility)
- US band = UK band (same inch ladder, steps of two)
- EU band = 60 + 5 × (UK band − 28) ÷ 2
- FR / ES / BE band = EU band + 15
- Cup steps = bust − band in whole inches (under one inch → AA, one → A, two → B, …), UK/US ladders diverging after DD as tabled above
- Sister size = band ± one step (two inches) with cup ∓ one letter, cup volume constant
Download the data
Free to reuse with attribution (CC BY 4.0): CSV · JSON. Columns: record_type, uk_band, us_band, eu_band, fr_es_be_band, bust_minus_band_in, us_cup, uk_cup.
How to cite this reference
Shape Finder, International Bra Size Conversion Reference, shapefinder.app/bra-size-conversion-reference/, reviewed 2026-07-10. CC BY 4.0.