Some discount airlines also eliminated the seat recline function so they can install additional seats to generate more revenue, the South Florida Sun Sentinel reported.
"If you're a low-cost carrier, you have to look at these moves" to stay price-competitive, said Matt Daimler, founder of SeatGuru.com, which tracks airline seating information.
Flights where seat rows are spaced farther apart can add up to 2 inches of legroom and passengers who desire the extra space might have to pay as much as $100 for the luxury, the report said.
Among U.S. air carriers, JetBlue offers coach passengers the most room between seats, but travelers desiring extra space can get up to 4 inches of additional legroom by paying a fee starting at $10 per "flight segment," the newspaper said.
"When you get on a plane, the first thing most people do is jack that seat back," said Joel Feldman, a JetBlue passenger who frequently flies between New York and South Florida. "When you have that extra space, it makes a difference."
Spirit Airlines offers passengers about 28 inches of legroom on its four new Airbus 320 aircraft, which have 178 seats that don't feature a recline function.
Spirit officials said the "pre-reclined" seats are lighter, minimize maintenance costs, and let passengers fly cheaper.