$121 Cheap Delta flights Ontario (ONT) to Billings (BIL)

Grab cheap return Delta Air Lines flights from $241 from ONT to BIL by filtering your results from "Price (lowest to highest)" on Expedia. Or look for bargains from $121 for a one-way journey.**These prices were available on Expedia within the past 7 days, for flights departing within the next year. Prices and availability are subject to change. Additional terms apply.

Begin your search one to three months before your departure to score cheaper fares on Delta Air Lines flights from Los Angeles - Ontario Intl. Airport (ONT) to Logan Intl. Airport (BIL). You can save 25% by booking your domestic flight 34 to 86 days in advance compared to last-minute reservations made 6 to 12 days out. You could also cut costs by buying your fare on a Sunday, as it's 6% cheaper on average than a Monday, the most expensive day to book.* Time it well, and you can enjoy significant savings on domestic journeys.*Ideal booking window recommendation is based on average round-trip ticket prices for January through November for 2024. Best day of the week to book recommendation is based on average round-trip ticket prices for January through October 2024. All data sourced from ARC's global airline sales database.

Sort your results by "Morning" and "Early Morning" to see the earliest departures from ONT to BIL. Leaving early means you're 20% less likely to experience cancellations.**Most reliable time of the day recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.

Delta Air Lines makes flying from ONT to BIL more enjoyable with an excellent in-flight experience and a rewarding loyalty program. You could even start collecting points with Delta SkyMiles. Be sure to join our free One Key™ rewards program to earn OneKeyCash™*, which can be redeemed on future bookings.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.