The purpose of this study was to investigate whether different components of encapsulation-style bras contribute to incorrect bra fit among women and whether this was influenced by breast size. The fit of five key bra components of 309 women’s own encapsulation bras was assessed using professional bra fit criteria among four breast size categories. Overall, incorrect fit prevalence was greatest among the cups, front band, and strap components of the bra. Although no significant difference was observed in overall bra fit between the four breast size categories, a significant difference was observed between groups for the front band, underwire, and strap components of the bra. Individual components of encapsulation-style bras are associated with incorrect bra fit and these vary with breast size. Incorporation of three-dimensional breast volume/shape and torso dimension data into bra component design could improve bra fit and breast support for women across the size spectrum.