The cost of air travel for children depends on the airline, the age of the child and where the flight is going. Children can travel for less than full price in some circumstances, especially if they are under the age of 2 years. However, many children pay full price for their seats on airplanes.
Kids Under 2
Most airlines allow each adult purchasing a ticket to carry one child under the age of 2 on her lap. Because this does not take up an extra seat, this "lap child" travels for free. The exception is on international flights, in which case the parent might have to pay approximately 10 percent of the standard fare to get a ticket for a lap child. If the parent chooses to not have the child under 2 on her lap, she will have to buy a separate seat for the child, likely at full price.
Lap Children Tips
The adult must be able to restrain the child during the whole flight without using a seat belt, so be aware that flight crews could kick you off the flight if you have a squirmy, screaming child you cannot safely restrain. In general, traveling with a child on your lap is not as safe as having the child buckled into a safety seat in the event of turbulence or a crash. If you are traveling with a lap child who can sit on his own, try booking a seat toward the back of the plane in hopes that you will have an empty seat next to you to sit your child in.
In the past, children under the age of 12 could travel for about 80 percent of the full ticket price. Most domestic airlines no longer offer this. Any child who has a seat pays full price in the United States and on most international trips to Europe, Mexico and the Caribbean. However, kids traveling to other destinations still might be able to get discounted tickets.
For domestic trips in reasonable driving distance, paying full price for a bunch of kids' plane tickets might not be worth the time saved by flying instead of driving. When you are flying outside the United States, compare airlines to find discounts for kids' tickets. You can also save money by booking early and setting up low-fare alerts on travel websites that compare many different airlines.