The size of personal belongings that travelers are permitted to bring on board is governed by the rules set forth by Frontier Airlines. Each ticket includes a complimentary personal item that must fit beneath the seat in front of you. Frontier's policy states that a personal item's maximum dimensions, including handles, wheels, and straps, are 14 inches high, 18 inches wide, and 8 inches deep (35.5 x 45.7 x 20.3 cm).