What Is the Smallest Bra Size?

The smallest bra sizes most brands make are AA cups on 28 or 30 bands. An AA cup means your bust is less than about an inch bigger than your band. Smaller than that, most people switch to bralettes in S/M/L sizing.

What is the smallest cup size?

AA is the smallest cup most brands label. Cup letters count the inches between your bust and your band: A is about 1 inch, B is 2, and so on. AA covers a difference smaller than an A.

Fewer brands make AA than A. ThirdLove lists cups starting at AA, and Victoria’s Secret’s international chart starts at AA, but many stores begin at A. Some brands occasionally use “AAA” for an even smaller cup, but it’s rare.

Our calculator shows a result below A as out of range rather than guessing. That’s partly because a loosely measured band can push the cup difference down by mistake. Re-measure your underbust snugly before deciding you’re an AA. The guide to measuring your bra size explains how.

What is the smallest band size?

The smallest band on most charts is 28. UK brands such as Freya and Curvy Kate list 28 bands on their charts. Many US brands start at 30 (Victoria’s Secret and Wacoal both state ranges from 30) or at 32.

Our calculator supports bands from 28. If your underbust rounds below 28, it’ll tell you that’s outside the range rather than suggesting a size that doesn’t exist.

Smallest overall bra sizes

The smallest combinations pair a small band with a small cup:

Remember that cup volume grows with the band. A 28A holds about the same as a 30AA, and a 32A holds about the same as a 30B. So “smallest” depends on both numbers. Our A cup guide shows how A cups compare across bands.

What if you measure smaller than the smallest size?

You have good options:

• Bralettes in S/M/L sizing often fit better than banded sizes at the very small end. Our guide to bralettes vs bras explains the difference.
• Camisoles with shelf bras give light coverage without a separate bra.
• Lightly lined or push-up bras in the smallest size you can find add shape if you want it.
• No bra at all is a perfectly good choice. A bra is about comfort and preference, not a requirement.

What to look for in bras for small sizes

• A firm band that sits level. On a small frame, even an inch of extra band makes a bra slide.
• Shallow cups with less fabric at the top, such as demi or plunge cuts, to avoid gaping.
• Close-set straps that stay on narrower shoulders.
• Adjustable or removable padding so you can choose the shape.

Our bras for small chests guide goes into each of these.