AU to US conversion

AU 8B in US Bra Size

Convert 8B from Australian sizing to US sizing, with the full international table, sister sizes, and practical fit checks in one place.

Instant answer

8B (AU) =

30B US

In this sizing table, 8B in Australian sizing converts to 30B in US sizing.

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If you are starting from body measurements instead of a known label, use the AU/NZ calculator with centimetres selected by default.

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Full conversion table for 8B (US 30B)

30B bra size conversion across US, UK, EU, French, and Australian sizing.
US	UK	EU	FR	AU
30B	30B	65B	80B	8B

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

What this conversion means

If you are shopping from a Australian size chart, use 30B as the closest US starting label for 8B. This is still a label translation, so brand grading, fabric, and wire shape can change the final fit.

Sister sizes for the US equivalent (30B)

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

What measurements make a 8B?

The useful way to read 8B is to separate the band from the cup step. In the current calculator formula, the closest starting range is about 29-31 inches (74-79 cm) under the bust and about 31.5-32.5 inches (80-83 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 30B as the US equivalent for those measurement notes.

Is 8B big or small?

Whether 8B feels small, average, or full depends on the body and on the brand. In this size set, the US equivalent uses a smaller 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 8B 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 8B differs between brands

8B can shift in feel from one retailer to another because brands grade bands and cups in their own way. 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 8B

8B is easiest to compare when you try shapes that show both cup volume and band tension clearly. 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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Everyday Fit Store

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Comfort Band Co.

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Soft Cup Edit

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FAQ

Is 8B the same as 30B in the US?

In this dataset, 8B (AU) converts to 30B 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 8B in European sizing?

8B (AU) matches the same base record as 65B (EU). The full table on this page shows each supported label side by side.

How do I check the fit of 30B?

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 30B?

32A are the closest sister-size options for 30B 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 8B?

8B maps to US 30B here. The current calculator formula points to about 29-31 inches underbust and 31.5-32.5 inches bust, or roughly 74-79 cm and 80-83 cm. Treat that as a starting range and then check the real fit.