As the travel season heats up and Americans hunt for the best airfares, airline rewards programs remain a good source of savings, according to a new study.

Personal finance website WalletHub looked at frequent flyer programs offered by the 10 largest domestic airlines, basing its ranking on 21 key metrics ranging from earnings policies to the value of a reward point or mile to redemption policies and blackout date policies.

The study found that frequent flyer programs, which are free to join, save travelers nearly 9% on airfare. It also found that many of the 10 largest U.S. airlines are sweetening their deals this year and that on average the top 10 airlines are offering 18% more value than they did last year.

Additionally, WalletHub said six of the 10 largest U.S. airlines allow program members to redeem miles with partner carriers.

Here is WalletHub’s ranking of the10 best frequent flyer programs for 2024:

10. Sun Country Airlines – Sun Country Rewards

Sun Country Rewards program’s points are worth an average of one cent per mile. There are no blackout dates on award flights, and members can book a flight on short notice without paying a fee.