You may be able to modify your itinerary for free in certain circumstances. Generally, there are penalties for changing or canceling an economy rate flight on any major U.S. airline, with the exception of Southwest Airlines. For a domestic journey, the cost may be as low as $25, but for an international flight, it can exceed $400. For further information regarding the policy, visit the official Delta website or give the airline a call at 1 (800) 221-1212. Call the flight expert at +1-800-865-1848 for immediate information on how much does it cost to change a delta flight, even if they are not available.