$149 Cheap American Airlines flights Atlanta (ATL) to Ontario (ONT)

Scoring cheap one-way American Airlines flights from ATL to ONT from $149 on Expedia couldn't be easier — just filter by "Price (lowest to highest)." Or check out our budget-friendly return fares from $313 for your next exciting adventure.**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.

For cheap American Airlines fares from Hartsfield-Jackson Atlanta Intl. Airport (ATL) to Los Angeles - Ontario Intl. Airport (ONT), start searching one to three months before your intended departure. Reserving domestic flights 34 to 86 days in advance could save you 25% compared to booking just 6 to 12 days ahead. The day you book can also affect what you pay. Sunday is usually the most affordable, while Monday is often the most expensive for domestic flights. You can save 6% on average by booking on a Sunday.**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.

Filter your results by "Morning" and "Early Morning" to see the earliest flights from ATL to ONT. Taking off 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.