AU to US conversion

AU 12A in US Bra Size

Convert 12A from Australian sizing to US sizing, with the full international table, sister sizes, and practical fit checks in one place.

Instant answer

12A (AU) =

34A US

In this sizing table, 12A in Australian sizing converts to 34A in US sizing.

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Full conversion table for 12A (US 34A)

34A bra size conversion across US, UK, EU, French, and Australian sizing.
US	UK	EU	FR	AU
34A	34A	75A	90A	12A

Bra sizing varies between brands. Use this as an accurate starting point and check the fit.

What this conversion means

This reverse conversion starts with the label you already have: 12A (AU). The matching US record is 34A, and the table shows the same size across UK, EU, French, and Australian systems for easier retailer comparison.

Sister sizes for the US equivalent (34A)

Sister sizes: 32B can be worth checking when the cup volume feels close but the band needs a different feel.

What measurements make a 12A?

12A is built from a band measurement and a bust measurement, not from the label alone. In the current calculator formula, the closest starting range is about 33-35 inches (84-89 cm) under the bust and about 34.5-35.5 inches (88-90 cm) around the fullest part of the bust. The band comes from the underbust rounding, while the cup step comes from the difference between bust and band. This page uses 34A as the US equivalent for those measurement notes.

Is 12A big or small?

12A is not automatically big or small; it depends on the band and the cup together. In this size set, the US equivalent uses a middle band and a lower cup step. Cup letters are relative to the band, so a D on one band is not the same volume as a D on every other band. The most useful question is whether the band stays level and the cups hold smoothly, not whether the label sounds large or small.

If 12A doesn't fit right

Band rides up: The band may be too loose or stretched out; try a snugger band or compare the snugger sister size.

Cups gape: The cup may be too roomy, too deep, or pulled away by a loose band; check the band before changing cup volume.

Cups spill: The cup volume may be too small or the cup shape may be too closed; try one cup step up before changing the band.

Straps dig in: The straps may be compensating for a band that is not supporting enough; reset the band fit before tightening straps.

How 12A differs between brands

Two brands can print 12A or its equivalent on the tag and still cut the bra differently. A firmer elastic can make the same band feel smaller, and a shallow or narrow cup can make the same cup letter feel different. Check the retailer chart, read fit notes when available, and compare the label against the brand and region sizing guide before treating the conversion as final.

Shopping for 12A

When shopping for 12A, start with styles that make the band easy to judge. If the cup is in a lower or middle step, lightly lined T-shirt styles can make gaps easy to spot. Fuller cup steps often benefit from styles with steadier side support, deeper cups, or a balconette shape depending on breast shape. For special outfits, compare the fit needs in the outfit guides before choosing a strapless, plunge, or backless option.

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FAQ

Is 12A the same as 34A in the US?

In this dataset, 12A (AU) converts to 34A in US sizing. Some brands publish their own charts, so use this as the closest standard label and still check the real fit.

What is 12A in European sizing?

12A (AU) matches the same base record as 75A (EU). The full table on this page shows each supported label side by side.

How do I check the fit of 34A?

Start with the band: it should feel firm and even around your ribcage. Then check cup containment, wire comfort, and whether the center gore lies close on wired styles.

What sister sizes work with 34A?

32B are the closest sister-size options for 34A in this dataset. Try a sister size when cup volume feels close but the band needs to feel snugger or looser.

Why do bra sizes differ between countries?

Bra labels are written differently across US, UK, EU, French, and Australian systems. Cup letters can also diverge after D, so a converted label is a starting point rather than a promise of identical fit.

What measurements usually make 12A?

12A maps to US 34A here. The current calculator formula points to about 33-35 inches underbust and 34.5-35.5 inches bust, or roughly 84-89 cm and 88-90 cm. Treat that as a starting range and then check the real fit.