$136 Cheap Flights from Washington (IAD) to Ontario (ONT)

View $136 flight on Thu, Jan 8, 2026Opens in a new window

Popular airlines from Washington Dulles Intl. Airport (IAD) to Los Angeles - Ontario Intl. Airport (ONT)

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Cheap Flights from Washington to Ontario (IAD-ONT)

Prices were available within the past 7 days and start at $136 for one-way flights and $226 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Southwest Airlines
Wed, Dec 10 - Tue, Dec 16
IAD
Washington
ONT
Ontario
$226 Roundtrip, found 4 days ago
$226
Roundtrip
found 4 days ago
Select Southwest Airlines flight, departing Wed, Dec 10 from Washington to Ontario, returning Tue, Dec 16, priced at $226 found 4 days ago
Southwest Airlines
Wed, Dec 10 - Tue, Dec 16
IAD
Washington
ONT
Ontario
$228 Roundtrip, found 4 days ago
$228
Roundtrip
found 4 days ago
Select Southwest Airlines flight, departing Wed, Dec 10 from Washington to Ontario, returning Tue, Dec 16, priced at $228 found 4 days ago
American Airlines
Wed, Dec 10 - Tue, Dec 16
IAD
Washington
ONT
Ontario
$236 Roundtrip, found 4 days ago
$236
Roundtrip
found 4 days ago
Select American Airlines flight, departing Wed, Dec 10 from Washington to Ontario, returning Tue, Dec 16, priced at $236 found 4 days ago
Delta
Wed, Dec 10 - Tue, Dec 16
IAD
Washington
ONT
Ontario
$243 Roundtrip, found 4 days ago
$243
Roundtrip
found 4 days ago
Select Delta flight, departing Wed, Dec 10 from Washington to Ontario, returning Tue, Dec 16, priced at $243 found 4 days ago
Southwest Airlines
Sat, Dec 6 - Tue, Dec 9
IAD
Washington
ONT
Ontario
$249 Roundtrip, found 6 days ago
$249
Roundtrip
found 6 days ago
Select Southwest Airlines flight, departing Sat, Dec 6 from Washington to Ontario, returning Tue, Dec 9, priced at $249 found 6 days ago
Southwest Airlines
Wed, Dec 10 - Tue, Dec 16
IAD
Washington
ONT
Ontario
$250 Roundtrip, found 4 days ago
$250
Roundtrip
found 4 days ago
Select Southwest Airlines flight, departing Wed, Dec 10 from Washington to Ontario, returning Tue, Dec 16, priced at $250 found 4 days ago
United
Wed, Dec 10 - Tue, Dec 16
IAD
Washington
ONT
Ontario
$259 Roundtrip, found 4 days ago
$259
Roundtrip
found 4 days ago
Select United flight, departing Wed, Dec 10 from Washington to Ontario, returning Tue, Dec 16, priced at $259 found 4 days ago
Delta
Wed, Jan 14 - Sat, Jan 24
IAD
Washington
ONT
Ontario
$259 Roundtrip, found 4 days ago
$259
Roundtrip
found 4 days ago
Select Delta flight, departing Wed, Jan 14 from Washington to Ontario, returning Sat, Jan 24, priced at $259 found 4 days ago
Southwest Airlines
Sat, Jan 10 - Sat, Jan 17
IAD
Washington
ONT
Ontario
$262 Roundtrip, found 6 days ago
$262
Roundtrip
found 6 days ago
Select Southwest Airlines flight, departing Sat, Jan 10 from Washington to Ontario, returning Sat, Jan 17, priced at $262 found 6 days ago
Frontier Airlines
Thu, Jan 15 - Thu, Jan 22
IAD
Washington
ONT
Ontario
$272 Roundtrip, found 2 days ago
$272
Roundtrip
found 2 days ago
Select Frontier Airlines flight, departing Thu, Jan 15 from Washington to Ontario, returning Thu, Jan 22, priced at $272 found 2 days ago

Find the cheapest month to fly from Washington (IAD) to Ontario (ONT)

September is typically the cheapest month to fly

From $181 - $626 per traveler.

Alternative airports near Ontario

Prices were available within the past 7 days. Prices and availability are subject to change.

Select flight to John Wayne SNA. Cheapest option available. Average driving time to city center is 42 minutes. Flights from $254
SNA
John Wayne
Cheapest
Average driving time to city center42 min
Flights from $254

Frequently asked questions

How much does a flight from Washington Dulles Intl. Airport (IAD) to Los Angeles - Ontario Intl. Airport (ONT) cost?
Secure a cheap one-way flight from $136 or cheap return flight from $226 from Washington Dulles Intl. Airport (IAD) to Los Angeles - Ontario Intl. Airport (ONT) with Expedia. Enter your travel dates and sort by "Price (lowest to highest)" to see our cheapest flight offers on this route.
What is the cheapest month to fly from Washington Dulles Intl. Airport (IAD) to Los Angeles - Ontario Intl. Airport (ONT)?
The cheapest month to fly from IAD to ONT is December, when demand is low. Off-peak season is often when you'll find cheap fares for travel between these airports.
What is the cheapest airline that flies from Washington Dulles Intl. Airport (IAD) to Los Angeles - Ontario Intl. Airport (ONT)?
Use the filter tool on Expedia to compare different airlines and find the most affordable carrier that'll take you from IAD to ONT. Then, sort your results by "Price (lowest to highest)" to pick up a good deal.
How many flights per day from Washington Dulles Intl. Airport (IAD) to Los Angeles - Ontario Intl. Airport (ONT)?
There aren't any daily direct flights from Washington Dulles Intl. Airport (IAD) to Los Angeles - Ontario Intl. Airport (ONT). But you can choose flights with layovers. Filter your search on Expedia to include one or more stops, and you'll be soaring above the clouds in no time.
What day of the week has the most flights from IAD to ONT?
Typically you'll find the largest variety of flight choices on a Friday. Tuesdays are often the quietest.* However, this can vary based on the time of year, carrier and other factors.*Busiest/quietest day to travel is based on Expedia flight demand through January to December 2024.
What is the best time to fly from Washington Dulles Intl. Airport (IAD) to Los Angeles - Ontario Intl. Airport (ONT)?
To arrive at Los Angeles - Ontario Intl. Airport (ONT) without delays, opt for a flight that leaves Washington Dulles Intl. Airport (IAD) before 3 PM. The likelihood of cancellations is 22% higher, on average, for departures after this hour.**Most reliable time of the day and month to travel recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.
What airports do you fly into for Ontario from Washington Dulles Intl. Airport (IAD)?
Los Angeles Intl. Airport (LAX) is the only airport in Ontario with direct flights from Washington Dulles Intl. Airport (IAD). Compare the options and discover affordable fares on Expedia.
Is it cheaper to buy a plane ticket from Washington Dulles Intl. Airport (IAD) to Los Angeles - Ontario Intl. Airport (ONT) last-minute?
Waiting until just before your departure to book a ticket from IAD to ONT generally means paying more. While you may find some last-minute deals, they aren't always guaranteed. Keep your travel plans flexible for a better chance of scoring a bargain.
Is it cheaper to book an IAD to ONT flight and hotel package?
Booking an IAD to ONT flight and hotel package is generally cheaper than booking separately. With Expedia, you can enjoy the convenience of organizing your trip in one place. Choose from our impressive range of hotels and then add flights, car rentals and activities to your booking. Bundle it all together, and you could save hundreds of dollars.
Can I cancel or change the date of my flight from Washington Dulles Intl. Airport (IAD) to Los Angeles - Ontario Intl. Airport (ONT)?
If you reserved your IAD to ONT flight within the last 24 hours, you may be able to modify or cancel it without any fees. Depending on the airline and the type of ticket you purchased, additional charges may apply for changes beyond that time. Airline policies and contact information can be found in your itinerary or confirmation email. Or, visit our Customer Service portal for further details.

Travel information

Origin airport
Washington Dulles Intl.
Destination airport
Los Angeles - Ontario Intl.
Airlines serving
Alaska Airlines, American Airlines, Delta, Frontier Airlines, Hawaiian Airlines, Southwest Airlines, United
Roundtrip price
$226
Distance
2236 mi
Average flight time
9 hours 41 mins

Book with confidence

Washington to Ontario Flights

The cheapest times to fly from Washington to Ontario

On average, Thursday can be the cheapest time to fly, according to data from the Airlines Reporting Corporation (ARC), one of the world's biggest databases for global airline sales. The data reveals that you could save up to 16% by flying on a Thursday—the cheapest day to travel on average—instead of a Sunday—the most expensive. Some of the most affordable flights from Washington to Ontario are during the month of December. You can find some of the cheapest flights from Washington to Ontario with Expedia's search tool and vast selection of airlines.

 

The best time to book a flight from Washington to Ontario

Sunday is one of the best days to book for cheap flights from Washington to Ontario: Tickets reserved on a Sunday cost between 6% and 13% less than those reserved on a Friday, according to ARC data. The data also suggests booking early can also lead to cheaper airfares. You could save 24% by buying your tickets for domestic flights at least a month in advance and 10% by booking international flights 2 months in advance.

 

How to find cheap round-trip tickets from Washington to Ontario

Being flexible with your dates and using Expedia's Price Drop Protection and Price Tracking features are some of the best ways of finding a cheap ticket from Washington to Ontario in 2025. You can also book with separate airlines for your outbound and return journeys, from $136 one-way. Expedia also offers Price Drop Protection, so if the cost of your airfare goes down after booking, you'll receive a credit for the difference*. This is available for a small fee, and is free to One Key Gold and Platinum tier members.

 

Expedia's Price Tracking feature means you can stay on top of airfares without manually checking every day. It sends you automated price alerts for cheap Washington to Ontario flights and uses historical data to indicate when the best time to book is. Download Expedia's free app to activate this handy tool in a few easy taps.

 

You could also save big by booking one of Expedia's vacation packages. Bundling together your Washington to Ontario airfare with your accommodations and car rental is often cheaper than booking everything separately. There’s also One Key, Expedia's generous rewards program. Join for free and you could earn One Key cash on most bookings to save on future adventures.

 

*Terms apply.

 

Disclaimer: ARC The statistics are based on average round-trip ticket prices between January and August 2023. The percentages you see are averages.

 

Washington to Ontario Flights

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*Available to One Key members.