The mid-tier class called Delta Comfort+ also has early boarding and deplaning, as well as more legroom and dedicated overhead space.

American Airlines

First: $1,240.23
Business: $642.86
Economy: $221.95

Over at American, upgrading to business from economy costs an average of $420.91. It’s just a few more dollars than at Delta but slightly less proportionally, at about 2.90 times an economy seat. That said, its first-class tickets are a major jump, $1,018.28 more than an economy, or a whopping 5.59 times more.

Similar to Delta, the first-class perks include priority check-in, security, boarding, and baggage, as well as more legroom varying by aircraft (usually between five and eight inches more). Meal services are included on flights over 900 miles.

American Airlines’ premium Flagship service is offered on five transcontinental routes (Los Angeles to New York City’s JFK, San Francisco to JFK, JFK to Orange County’s SNA airport, Los Angeles to Boston, and Los Angeles to Miami). Flagship First includes suites with lie-flat seats and access to the Flagship lounge at the airport. First class passengers also enjoy dining from Chef Sam Choy and Chef Sarah Grueneberg through a partnership with the James Beard Foundation, plus upgraded amenity kits with items from Joanna Vargas and Relevant, as well as slippers from Nest Bedding. The Flagship Business class also has lie-flat seats, and a similar chef dining and amenity kit.

Alaska Airlines

Business: $666.09
Economy: $207.23

While Alaska and Hawaiian have merged, they still operate separately—and Alaska offers a fair deal to go from economy to business for an additional $458.86, or 3.21 times more.

For its “First Class,” the Seattle-based airline proudly boasts the most legroom for upright seats on any domestic flight, plus a 41-inch pitch, leather upholstering, a footrest, and tablet holder. Two checked bags are also included, as well as free beer, wine, and cocktails and the ability to preorder complimentary meals.

United Airlines

Business: $761.91
Economy: $209.45

United’s premium classes vary by flight route and aircraft type. United is the only US carrier that calls its highest domestic class “business class” (though some flights also have three classes with premium economy). Generally speaking, an upgrade from economy to a premium class is the most expensive of the big three US carriers at an additional $552.46, or 3.64 times more. However, Cirium notes that United offers one of the best premium classes in the US skies.

United First and Business is offered on domestic flights, with more space to recline, six-way adjustable headrests, extra storage space, cocktail table in addition to the tray table, and hot entrees on flights over 900 miles. Those flying between the continental US and Hawaii also get an amenity kit with items from clean beauty company Ua Body.

On most flights between Newark Liberty International and Los Angeles and San Francisco, Premium Transcontinental Service is offered, with its business class getting full recline seats, bedding from Saks Fifth Avenue, and a 15-inch screen.

JetBlue

Business: $648.91
Economy: $155.73