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Bra Size Calculator Australia

Measure in centimetres - the calculator opens in cm - and get your Australian band number and cup letter, with the conversion to UK, US and EU sizing alongside it.

The six-measurement method of the A Bra That Fits community. The band comes from the snug underbust; the cup from the leaning bust and the loose underbust. The tight underbust does not change your size - it adds a note on how firm a band will feel - so you can leave it out. Implemented independently and not affiliated, so a result can differ from theirs. How to take all six.

Not sure where the tape goes? See how to take both measurements.

If your breasts sit low or are soft, add one more measurement

Try it

Move the measurements and watch the size change

Both drawings are the same body: from the side, and sliced across and seen from above. Drag either measurement and both redraw.

Measurements

One body, two views

from the side
from above
Size
12D
Bust
96.5 cm
Across the chest
16.9 cm
Weight, each
423-879 g

The Australian band number is an inch measurement in disguise

Australian bras are labelled 8, 10, 12, 14, 16 and upward, which looks like dress sizing and is often assumed to be metric. It is neither. The number is your ribcage measurement in inches, minus 22.

  • 30 inches (76 cm) → size 8
  • 32 inches (81 cm) → size 10
  • 34 inches (86 cm) → size 12
  • 36 inches (91 cm) → size 14
  • 38 inches (97 cm) → size 16
  • 40 inches (102 cm) → size 18

This matters for accuracy. Because the underlying grid is in two-inch steps, a centimetre chart has to round, and the rounding boundaries sit at odd places - 84 cm and 89 cm rather than at any round metric number. Measuring in centimetres and converting once, as this calculator does, avoids being rounded twice.

Cup letters follow Britain, not America

Australia inherited the British cup ladder, so above a DD the letters continue E, F, FF, G, GG rather than stacking into DDD. One inch of difference between bust and band is one letter, the whole way up.

That is the half of the conversion most often missed when ordering from American sites. An Australian 12E is an American 34DDD - the band converts by adding 22, and the cup converts by a completely separate rule. Getting the band right and the cup wrong is the standard failure.

Measuring in centimetres, properly

Take the underbust snug against the ribs, breathing out, and the bust with the tape resting rather than pulling. Both must be level all the way round - check the back in a mirror, since a tape that has crept up behind you is the usual cause of a wrong result.

One Australia-specific note: if you are measuring in a hot climate or straight after exercise, wait. Ribcage circumference measured while breathing hard can read a centimetre or more over its resting value, which is enough to push you across a band boundary.

Full Australian conversion tables

The AU/NZ column is highlighted. Band numbers first, then cup letters against every other system.

Band sizes

US and UK bands are the same number of inches. Everything else is metric: the EU band is the ribcage measurement in centimetres rounded to the nearest 5, France adds 15 to the EU number, Italy counts those same 5cm steps as 1, 2, 3, and Australia subtracts 22 from the inch band.

USUKEUAU/NZJPFRIT
282860-6075-
303065865801
3232701070852
3434751275903
3636801480954
38388516851005
40409018901056
42429520951107
4444100221001158
4646105241051209

Cup letters

Every system agrees up to D. Above it they split three ways, and this is where almost all conversion errors happen: the UK inserts single letters between its doubles, the US stacks Ds and then jumps to G, and the continental systems just carry on through the alphabet. A UK E is a US DDD, not a US E. Past a 15-inch difference American labelling simply stops, which is why the US column runs out before the others do.

DifferenceUSUKEUAU/NZJPFRIT
1"AAAAAAA
2"BBBBBBB
3"CCCCCCC
4"DDDDDDD
5"DDDDEDDEEE
6"DDDEFEFFF
7"GFGFGGG
8"HFFHFFHHH
9"IGIGIII
10"JGGJGGJJJ
11"KHKHKKK
12"LHHLHHLLL
13"MJMJMMM
14"NJJNJJNNN
15"OKOKOOO
16"-KKPKKPPP
17"-LQLQQQ
18"-LLRLLRRR

Why the calculated size may look unfamiliar

This calculator does not add four inches to your ribcage measurement before working out the cup, which most in-store fittings historically did. Here is what each method makes of the same tape measurements.

Why your size may look unfamiliar

14Bbecomes10E

A 32" ribcage with a 38" bust, fitted the old way and measured directly. The band drops 2 sizes and the cup climbs 4 letters, because the old method took the cup from a band four inches too big. Same volume. Different garment.

The total volume is unchanged. What changes is that the band, rather than the straps, is doing the supporting.

Other pages

Questions people actually ask

How do Australian bra sizes work?
The band is a dress-style number - 8, 10, 12, 14, 16 - and it is simply the ribcage measurement in inches minus 22. A 34-inch ribcage is a size 12. The cup letters then follow the British ladder: D, DD, E, F, FF, G. So a UK 34E is an Australian 12E, exactly the same garment with a different number on the band.
What is a size 12 bra in Australia?
A 12 band is a 34-inch ribcage, the same band an American or British label would call a 34. The cup letter is unchanged from British sizing, so 12C, 12DD and 12F are 34C, 34DD and 34F. Australian labels vary in whether they print 12C or 34C, and some print both.
Should I measure in centimetres or inches in Australia?
Measure in centimetres, because that is what your tape almost certainly reads, and let the calculator convert. The sizing system itself is inch-based underneath - the 8/10/12/14 band numbers derive from inches, not from any metric measurement - so a chart that maps centimetres straight onto band numbers is doing a rounded conversion whether it admits it or not. Entering your real centimetre figure and converting once is more accurate than reading off a banded chart.
Is Australian sizing the same as New Zealand sizing?
Yes. New Zealand uses the same band numbering and the same British-derived cup ladder, and brands sell across both markets on one size label.
Why does my Australian size not match the American size I ordered online?
Two separate shifts stack up. The band number changes by 22 - an Australian 12 is an American 34 - and above a DD the cup letters stop meaning the same thing, because Australia follows the British ladder and America does not. An Australian 12E is an American 34DDD. Getting only one of the two conversions right gets you the wrong bra.
What is the equivalent of an Australian 14DD?
A 14 band is a 36-inch ribcage, and DD is five inches of difference in both the Australian and American systems, so a 14DD is a 36DD in the United States, a 36DD in the UK, and an 80E in European sizing. DD is the last size where the letters line up without translation.