Formerly, baseball caps came in standard hat sizes. Since 1980, they have commonly come in a one-size-fits-all form, with an adjustment strap in the back. This simplifies marketing, but it reduces sun protection for bald men. More recently, advances in textiles have led to the "stretch-fit" hat, which uses Lycra or rubber to allow a hat to have a fitted style while still being "adjustable" within sizes.

Athletes in other sports wear caps with their team's logo and colors as "sideline" caps; both types are also sold as authentic team merchandise in retail stores and are quite popular. Other caps may simply have a company's logo, such as Reebok, Nike or Carhartt; these hats are often made of brushed cotton. Golfers tend to prefer the visor form of cap which does not cover the head but keeps the sun out of their eyes; women also traditionally have worn visors casually but a trend towards certain youth subcultures see an increase in visor popularity among both sexes.