One infant is permitted to travel free on U.S. domestic flights per each paying guest 12 years of age or older. An infant is considered a child under 2 years of age who does not occupy a seat.
Each additional child under 2 years of age who accompanies the same adult passenger will pay the applicable accompanied child's fare whether they are occupying a seat or not. Children 2 years of age or older must be seated in an approved seat.