The airline says the new structure will allow for greater flexibility when redeeming miles and will better recognize frequent business travelers and leisure flyers who buy premium fares.
The changes take effect starting next year.
A year ago, it announced that starting in 2014 passengers would need to spend at least $2,500 with the airline to qualify for the lowest level of elite frequent-flier status, which carries perks such as free upgrades and a waiver from bag fees. Before that, they could qualify on miles alone. United quickly matched Delta's change.
Virgin America and JetBlue Airways Corp.'s "True Blue" frequent-flier program award points based on dollars spent, not miles flown. Southwest Airlines Co., which carries more passengers within the U.S. than any other airline, overhauled its Rapid Rewards program in 2011 to award free tickets based on money spent, not trips taken. It seems to be paying off; a spokeswoman said the changes boosted Southwest revenue by $180 million in 2012 and an additional $100 million last year.
Delta Air Lines Inc., based in Atlanta, said that beginning Jan. 1, SkyMiles members will earn between 5 and 11 miles for every dollar they spend on tickets - the low end for general customers, and the biggest bang for elite Diamond Medallion members. All of them will continue to get a bonus for buying tickets with a Delta-branded credit card.
Other changes, Delta said, include more availability of reward seats at the lowest mileage-requirement levels, one-way awards at half the miles needed for a round-trip reward - American does that now - and more options to combine miles and cash when buying tickets.
The Associated Press contributed to this report.