Apex Conversion

👙 US Bra Size to AU Bra Size Converter

Free online tool to convert US bra sizes to AU. Enter your band and cup size for an instant, accurate result — band and cup both converted.

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Result

12C

34C US = 12C AU

US Bra Size to AU Bra Size Conversion Table

US SizeAU Size
30A US8A AU
30B US8B AU
30C US8C AU
30D US8D AU
30DD US8DD AU
30DDD US8E AU
32A US10A AU
32B US10B AU
32C US10C AU
32D US10D AU
32DD US10DD AU
32DDD US10E AU
34A US12A AU
34B US12B AU
34C US12C AU
34D US12D AU
34DD US12DD AU
34DDD US12E AU
36A US14A AU
36B US14B AU
36C US14C AU
36D US14D AU
36DD US14DD AU
36DDD US14E AU

Conversion Formula

Band conversion reference:
  US/UK:  28   30   32   34   36   38   40   42   44
  EU:     60   65   70   75   80   85   90   95  100
  FR:     75   80   85   90   95  100  105  110  115
  AU:      6    8   10   12   14   16   18   20   22
  JP/RU/KR: same as EU

Cup conversion — canonical index (12 sizes, index 0–11):
  US:     AA  A   B   C   D   DD  DDD  G   H   I   J   K
  UK/AU/FR: AA  A   B   C   D   DD   E   F  FF   G  GG   H
  EU/JP/RU/KR: AA  A   B   C   D   E   F   G   H   I   J   K

Common mistakes:
  US DDD ≠ UK DDD — US DDD = UK E
  US G ≠ EU G — US G = EU G (index 7 matches here)
  US DD = UK DD (same), but US DD = EU E (different)

About US Bra Size to AU Bra Size Conversions

The US and AU sizing systems use different band scales and diverge in cup notation above D cup. This converter handles the full size — band and cup — so you get an accurate result rather than just a band approximation.

This conversion uses a non-linear (reciprocal) relationship, so a simple multiplication factor does not apply. The formula section below explains the method, and the reference table shows common converted values.

This page includes a reference table of common US Bra Size values pre-converted to AU Bra Size, the conversion formula, and frequently asked questions. All values use internationally recognized conversion standards.

Frequently Asked Questions

How do I convert US Bra Size to AU Bra Size?

This conversion is non-linear. Use the calculator above for accurate results, or refer to the formula section on this page.

How many AU Bra Size are in 1 US Bra Size?

The relationship between US Bra Size and AU Bra Size is non-linear. Use the calculator above or the reference table on this page for specific values.

Is US Bra Size larger or smaller than AU Bra Size?

The size relationship between US Bra Size and AU Bra Size depends on the input value because this conversion is non-linear (reciprocal).

When would I use AU Bra Size instead of US Bra Size?

Use AU sizing when shopping brands that label their products in the AU system — for example, European luxury brands, UK high street stores, or Japanese lingerie retailers. Always verify sizing with the brand's own chart, as fit can vary by style and manufacturer even within the same system.

Why doesn't my cup letter stay the same when converting between systems?

Cup letters are only consistent up to D cup. From DD upward, the US uses DD, DDD, G, H, I while UK and AU use DD, E, F, FF, G, GG, H, and EU uses E, F, G, H, I. This means US 34DDD = UK 34E = EU 75F. The band number also changes because each system uses a different scale — US in even inches, EU and JP in 5 cm increments, FR adds 15 to the EU number, and AU uses garment numbers.

What is the most common conversion mistake with international bra sizes?

The most common mistakes are (1) keeping the cup letter unchanged when it should change — US DDD is NOT UK DDD, it is UK E; and (2) only converting the band while ignoring the cup. Both band and cup must be converted for an accurate size. A second common mistake is confusing EU and FR sizing: FR sizes are EU + 15 in the band but use the same cup letters.

Related Bra Size Conversions

AU Bra Size → US Bra SizeUnited States (US) → European (EU)European (EU) → United States (US)United States (US) → United Kingdom (UK)United Kingdom (UK) → United States (US)
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All conversion results are provided for general informational purposes only. Our formulas use internationally recognized conversion factors; however, rounding may affect precision. Do not rely on these results for professional, medical, legal, or engineering decisions without independent verification. Read our full disclaimer.