Southwest Airlines is the latest major carrier to downgrade the value of loyalty points.
It says points earned will have varying value based on route, time and day of travel, and general customer demand.
These new changes will start from April 17 but the airline has not yet disclosed how many miles will be needed for each reward flight.
Southwest confirmed the value of points will vary on some flights but others will remain the same.
"In an effort to stay competitive in the current market conditions and provide the most customer-friendly redemption policies in the airline industry, Southwest Airlines has slightly increased the number of Rapid Rewards Points needed to redeem flights," a statement said.
Brian Karimzad, director of the rewards program site MileCards.com said it will be difficult for fliers to work out how many points are needed to redeem flights on any given day.
"The loss to consumers is no longer knowing how much your points are worth in advance. Now, what they’re worth will be at the whim of Southwest’s revenue management policies each day."
