The smallest standard bra size commercially produced by major manufacturers is generally considered to be a 28AA or 30AA. The "number" (28 or 30) refers to the band size, which is the circumference of the ribcage directly under the bust, measured in inches. The "letters" (AA) refer to the cup size, representing the difference between the band measurement and the measurement around the fullest part of the chest. An "AA" cup typically indicates a difference of less than one inch between these two measurements. While 28AA is a standard starting point in many "teen" or "training bra" lines, some specialty petite brands and bespoke lingerie makers produce even smaller bands, such as a 24 or 26, though these are much harder to find in traditional retail stores. It is a common misconception that "A" is the smallest; "AA" and "AAA" are specifically designed for those with very shallow breast tissue or smaller frames. Finding the correct fit is crucial, as many people with smaller busts mistakenly wear a band that is too large (like a 32A) when they actually need a smaller band and a different cup volume to ensure the bra provides proper support and stays in place without riding up the back during daily movement.