Do babies fly for free? Children under two years old can fly for free domestically on most airlines when carried onboard as a lap child. If you want to buy your baby their own seat, you'll need to book them a ticket.

Whether a baby pays for a flight depends on their age and where you are flying. For domestic flights (within the same country), infants under age 2 usually fly for free as a "lap child," though they must still be added to the reservation. For international flights, most airlines charge an "infant fare," which is typically 10% of the adult fare plus taxes and fees. If you want your baby to have their own seat for safety (using an FAA-approved car seat), you must purchase a full ticket, though some carriers offer a "child discount" of 25% off the adult price for passengers under 12. In 2026, many budget airlines like Ryanair or Spirit charge a flat infant fee (around $25–$35) even for lap children. It is vital to check your specific airline's policy, as some may also include a free checked stroller or car seat, while others might count a diaper bag as your only carry-on item.