Wacoal bra size chart, converted to UK and US sizes
"wacoal bra size chart" gets 1,900 US searches a month. Wacoal sizes in US letters that run all the way to O, prints its own US/UK pairing on its chart, and its fit calculator padded the band by 2 to 3 in in every run we recorded. Read from Wacoal's own chart and calculator on 26 September 2026.
Same tape, three answers
| Method | Result |
|---|---|
| Bra Atlas (measured band) | 34D |
| Wacoal's calculator | 36B |
| ThirdLove's calculator | 36A (see the ThirdLove page) |
Wacoal's 36B holds less cup volume than our 34D: five of our test runs on its calculator all follow one rule, band = underbust + 2 in (or +3 if odd), cup = bust minus that band. Padding the band before reading the cup is the same pattern White and Scurr (2012) measured against professional fitting. Neither answer is "wrong" for Wacoal's own bras; it means a Wacoal size does not carry over to another brand.
Wacoal did not pay for a mention. We quote what its chart and calculator printed and say where that differs from a measured-band size; we don't claim Wacoal "runs small".
What Wacoal's own chart and calculator say
From wacoal-america.com's size charts page and its bra fit calculator.
What its calculator printed
Five of our tape measurements returned a size: 29/33 in gave 32A, 33/37 gave 36A, 34/38 gave 36B, 36/41 gave 38C and 38/44 gave 40D. Every one fits the same rule: band = underbust + 2 (or + 3 if odd), cup = bust minus that band, one letter per inch. Three other pairs (30/34, 32/35, 28/30) returned "Your overbust measurement should be larger than your underbust" in two separate runs.
What its chart shows
Wacoal America's size chart page prints the US and UK cup ladders side by side: US DDD = UK E, US G = UK F, US H = UK FF, up to US O = UK K. That is exactly the ladder our converter uses.
Converting a Wacoal size
Wacoal's own chart pairs its US cup letters with UK letters one for one, from AA up to O. That is exactly the pairing our engine uses, so a Wacoal label converts the same way any US size does.
| Band | AA | A | B | C | D | DD | DDD | G | H | I | J | K | L | M | N | O |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 32 | 32AA | 32A | 32B | 32C | 32D | 32DD | 32E | 32F | 32FF | 32G | 32GG | 32H | 32HH | 32J | 32JJ | 32K |
| 34 | 34AA | 34A | 34B | 34C | 34D | 34DD | 34E | 34F | 34FF | 34G | 34GG | 34H | 34HH | 34J | 34JJ | 34K |
| 36 | 36AA | 36A | 36B | 36C | 36D | 36DD | 36E | 36F | 36FF | 36G | 36GG | 36H | 36HH | 36J | 36JJ | 36K |
| 38 | 38AA | 38A | 38B | 38C | 38D | 38DD | 38E | 38F | 38FF | 38G | 38GG | 38H | 38HH | 38J | 38JJ | 38K |
Built from the same conversion engine as the rest of the site (src/lib/engine.ts); nothing here is typed by hand. A Wacoal 34O, for example, reads 34K on our chart and EU 75O. Full six-system conversions, including France, Australia and Japan, are on the converter.
Sources
Each source was opened and checked on the date shown, or on 25 September 2026. Where sources disagree, the page says so instead of picking one silently.
- Wacoal America, "Size Charts": US and UK cup ladders side by side (opened 26 September 2026)
- Wacoal America, "Bra Fit Calculator": measurements in eighths of an inch; calculator run with 8 measurement pairs (opened 26 September 2026)
- White J, Scurr J. Evaluation of professional bra fitting criteria for bra selection and fitting in the UK. Ergonomics 2012;55(6):704-711: 45 women; the traditional method overestimated band and underestimated cup