What is the Smallest Bra Size?

You've measured yourself carefully, tried on countless bras, and still can't find one that fits right. The problem might not be you; you just may need a smaller bra size than you thought. 

Knowing about small bra sizes opens up properly fitting options that actually work with your body.

The Smallest Bra Sizes

The smallest bra size commonly available is 28AA. Some specialty retailers produce 28AAA, though these are harder to find.

A 28AA indicates a 28-inch band with less than one inch difference between your ribcage and bust measurements. AA and AAA cups are smaller than A cups. AAA represents the smallest available cup volume. Many people assume A is the starting point, but the alphabet continues backward for smaller volumes.

Cup size is relative to band size. A 32AA contains more volume than a 28AA because the band is larger. When the band increases by one size, the cup volume of the same letter also increases slightly. This relationship between band and cup means your size changes if either measurement shifts.

How Small Bra Sizes Are Calculated

Band size comes from measuring around your ribcage directly under your breasts. Pull the measuring tape snug but not tight. You should be able to breathe comfortably. 

Cup size is determined by the difference between your bust and band measurements. Measure around the fullest part of your chest, keeping the tape level across your back. 

A difference of less than 1 inch = AAA cup
A difference of 1 inch = AA cup
A difference of 2 inches = A cup
A difference of 3 inches = B cup

Sister sizing can help you find an alternative size when your cup capacity is perfect, but the band needs slight adjusting. If you're looking for a bigger band size but want to keep the same cup volume, go up one band size and down one cup. If you're looking for a smaller band size with the same cup volume, go down a band size and up one cup size. For example, a 30A and 32AA are sister sizes with similar cup volumes but different band lengths.

Proper measuring technique matters more than you might think. Measure while wearing an unpadded bra or no bra at all. Stand straight with your arms at your sides. Take measurements at the same time of day, as breast tissue can fluctuate with hormones, hydration, and temperature. To find your bra size instantly and accurately, use our bra size calculator.

Common Misconceptions About Small Bra Sizes

Many people believe small breasts don't need support. In fact, all breast tissue benefits from proper support regardless of size. A well-fitted bra prevents tissue stretching over time, provides a smooth silhouette under clothing, and distributes weight evenly across your shoulders and back. 

Small cup sizes can wear the same variety of designs as any other size: lace details, seamless t-shirt styles, plunge necklines, balconettes, and more. The challenge lies in finding brands that manufacture these styles in smaller sizes, not in the styles themselves.

Another misconception suggests one size fits all small busts. Your breast shape, root width, projection, and spacing vary independently of volume. Two people wearing 30AA might need completely different styles based on whether their breasts sit close together or wide apart, whether tissue is concentrated at the top or bottom, and how far the breast projects from the chest wall.

Finding the Right Fit for Smaller Busts

A properly fitted bra sits level across your back. The band shouldn't ride up toward your shoulder blades. Check this by looking in a mirror from the side. The band provides most of the bra's support, so it needs to be snug without digging in.

Cups should lie smoothly against your breast tissue without gapping at the top or sides. The fabric conforms to your shape rather than standing away from it. Press gently on the cup; if it moves away from your body easily, you need a smaller cup or different style.

The center gore, aka the piece of fabric between the cups, is meant to sit flat against your sternum. If it floats away from your chest, the cups are too small or the wrong shape for your breast spacing.

Straps are designed to stay in place on your shoulders without digging grooves into your skin. Adjust them so they provide light support without bearing the weight of your breasts. If you need to tighten straps significantly to feel supported, your band is too loose.

Gapping at the top of cups often means the cup is too large, too tall, or designed for more upper fullness than you have. Try a smaller cup size or a style with a lower cut like a balconette or demi cup. Sometimes gapping happens because the bra is designed for a different breast shape, even if the volume is correct.

Best Bra Styles for Smaller Cup Sizes

Soft cup bras without underwire offer comfortable support through fabric structure and band tension alone. The lack of rigid materials means the bra conforms to your unique shape. Many people find soft cups more comfortable for all-day wear, especially in smaller sizes where underwire isn't necessary for support. The Silhouette Bra is a great soft-cup wireless option for small cup sizes as it offers comfortable support, structure, and shaping.

Shop Silhouette Bra

Lightly lined bras feature thin padding that creates a smooth silhouette under clothing without adding volume. The light lining prevents visible texture while maintaining your natural shape. Look for seamless construction that disappears under fitted tops, like the CloudEmbrace Bra.

Shop CloudEmbrace Bra

Adjustable straps let you customize the fit to your torso length and shoulder width. Closer-set straps prevent slipping on narrower frames. Look for fully adjustable straps that can be shortened significantly, like the straps featured on the CrossOver Bra.

Shop CrossOver Bra

Bralettes provide relaxed support through stretchy fabrics and simple construction. Without molded cups or underwires, they work well for smaller volumes that don't require structured support. Many bralettes feature beautiful lace or mesh details.

We design bras in a full range of sizes, including options that work beautifully for smaller cup sizes. You can explore our bra collection to find styles that provide the right support and comfort for your unique shape.