Frontier Airlines ensures to make your travel experience hassle-free without compromising on your travel needs. Moreover, one can select a seat assignment by paying an additional fee when purchasing tickets or while flight check-in. The seat fare may vary with different factors. On booking online seats up to 24 hours before departure, pay $6 and $20 for standard and stretch seats, respectively. However, the airline charges $8 and $20 for making a Frontier Airlines seat selection at a call center.