AA Cup Size
An AA cup is a bust measurement the same as, or within half an inch of, the band: a zero-inch difference, one position below A. The letter is identical in US, UK and EU sizing.
What is an AA cup?
A AA cup means the fullest bust measurement is 0 inches (≈ 0 cm) larger than the underbust band. The letter is identical in UK and EU sizing: AA. It is not a fixed volume: what the cup holds grows with the band it sits on.
Same letter, nine volumes. A 28AA and a 44AA are both “AA cups”: the second holds several times the volume of the first.
Every AA-cup size
The same 0-inch difference on each band. Read across for measurements, sister sizes and the EU / FR / AU labels; tap a size for its full guide.
| Size | Underbust | Bust | Sister sizes | EU · FR · AU |
|---|---|---|---|---|
| 28AA | 27–28″ · 69–71 cm | 28″ · 71 cm | — · — | 60AA · 75AA · 6AA |
| 30AA | 29–30″ · 74–76 cm | 30″ · 76 cm | 28A · — | 65AA · 80AA · 8AA |
| 32AA | 31–32″ · 79–81 cm | 32″ · 81 cm | 30A · — | 70AA · 85AA · 10AA |
| 34AA | 33–34″ · 84–86 cm | 34″ · 86 cm | 32A · — | 75AA · 90AA · 12AA |
| 36AA | 35–36″ · 89–91 cm | 36″ · 91 cm | 34A · — | 80AA · 95AA · 14AA |
| 38AA | 37–38″ · 94–97 cm | 38″ · 97 cm | 36A · — | 85AA · 100AA · 16AA |
| 40AA | 39–40″ · 99–102 cm | 40″ · 102 cm | 38A · — | 90AA · 105AA · 18AA |
| 42AA | 41–42″ · 104–107 cm | 42″ · 107 cm | 40A · — | 95AA · 110AA · 20AA |
| 44AA | 43–44″ · 109–112 cm | 44″ · 112 cm | 42A · — | 100AA · 115AA · 22AA |
The AA cup, in numbers
Volume is the pairing, not the letter. At the bottom of the ladder the clinical weight model does not resolve individual cups; root width and band decide the fit far more than depth does.
Is an AA cup big?
A zero-inch difference is the bottom of the standard ladder, and volume here is small enough that the clinical weight model does not resolve it; shape and root width matter more than depth. It is also where band choice dominates: an AA on a 28 and an AA on a 38 are different garments with a shared letter.
AA is the size most often mis-sold as an A or a 32B by charts that add inches to the band: a 30-inch ribcage measured snugly with a 30-inch bust is a 30AA, which an add-four chart calls a 34A and which fits nowhere.
Key takeaway: “AA cup” describes a 0-inch difference. Volume depends on the band; convert by position, never by letter.
What people get wrong about AA cups
Measured AA, sold something else?
Add-inches charts cannot produce an AA: they inflate the band and hand the wearer a larger cup that stands off the chest. Measured snugly, the band is right and the cup comes from a specialist.
AA cup in UK, EU and other systems
4″ difference. Matches UK and EU letters.
Identical to US. Full-bust specialists (Panache, Freya, Curvy Kate) label in UK letters.
Identical to US. FR, IT, DE and JP use EU cup letters.
Convert any exact size with the size converter.
Bra styles that fit an AA cup
Shallow cups want unlined or lightly lined wireless, bralettes, demi and plunge cuts with a low, narrow gore; full-coverage moulded cups gape. Small-bust specialists cut AA with real wires; mass market mostly does not.
Frame like a 28 band, also look for narrower wires and shorter straps The same AA cup is deeper and narrower here.
The widest choice of styles at this cup. Molded for a smooth line, seamed for shape and lift.
The AA cup is wider and shallower; prioritise a firm, wide band and a wire that fully encloses the root. Longline and three-hook styles help.
Shape matters as much as size: see the fit guide for the five breast shapes and the constructions that suit each.
AA cup: answered
How big is an AA cup?
An AA cup is a bust measurement within about half an inch of the band, a zero-inch difference and one position below A. The letter is the same in US, UK and EU sizing. Volume depends on the band: a 36AA is a wider, larger breast than a 30AA.
Is AA smaller than A?
Yes, by one inch of projection. A is a one-inch bust-over-band difference; AA is zero. It is the same one-inch step as between any two adjacent letters.
What is my AA size in UK or EU sizing?
The same letter: AA is AA in all three systems. Only the band converts: a US 32AA is an EU 70AA and a FR 85AA.
What are the sister sizes of a 34AA?
A 32A holds the same volume on a smaller band. There is no larger-band sister in standard notation, since there is no cup below AA on a 36.
Which brands make AA cups?
Small-bust specialists such as Pepper and Lula Lu cut AA with structure; among mass-market brands availability is thin and often bralette-only. The small-bust guide lists what the site has verified.
Opens the matching HauteFlair collection; use your measured size there. HauteFlair is owned by the same company as Brasize.ai; that relationship never changes the sizing math, charts, or fit advice on this page. How this site makes money.
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