IAD - ONT

$85 Find Cheap Flights from Washington Dulles Airport to Ontario

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Dulles Intl to Ontario departing on 1/18. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy, 0 bags

KAYAK searches hundreds of travel sites at once for deals on flights to Ontario

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Washington, D.C. to Ontario, as well as popular online travel agencies
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Washington, D.C. to Ontario, as well as popular online travel agencies
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Everything you should know

Cheapest round-trip
$237
Overall average: $368
United Airlines
Wed 4/22Wed 4/22
IAD - ONT • 1 stop
Cheapest one-way
$88
Typical prices: $377-$423
Frontier
Sun 1/18
IAD - ONT • 1 stop
Top airlines
Delta
Cheapest • from $293 (round-trip)
Southwest
Best reviews • 8.0 score
Airline reviews
Airline reviews
+1
+1
Airline reviews
Airline reviews
+1
When to travel
September
Cheapest • 41% price drop
November
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
+1
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Flight Deals
Booking Insights
Flight Deals

Cheap Flights from Dulles Intl to Ontario (IAD-ONT)

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Dulles Intl to Ontario that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from Dulles Intl to Ontario

Wed, Apr 22 - Wed, Apr 22
United Airlines Logo
6:30 am - 12:14 pm
IAD
-
ONT
8h 44m1 stop
United Airlines Logo
6:49 pm - 7:50 am
ONT
-
IAD
10h 01m1 stop
$237United Airlines
Tue, Feb 17 - Wed, Mar 18
Delta Logo
7:05 am - 12:07 pm
IAD
-
ONT
8h 02m1 stop
Delta Logo
1:20 pm - 11:40 pm
ONT
-
IAD
7h 20m1 stop
$257Delta
Sun, Feb 8 - Wed, Feb 11
Frontier Logo
10:50 am - 4:26 pm
IAD
-
ONT
8h 36m1 stop
Frontier Logo
8:10 am - 4:43 pm
ONT
-
IAD
29h 33m2 stops
$261Frontier
Wed, Apr 22 - Wed, Apr 22
Delta Logo
6:00 am - 11:29 am
IAD
-
ONT
8h 29m1 stop
Delta Logo
5:05 pm - 9:15 am
ONT
-
IAD
13h 10m2 stops
$262Delta
Wed, Jan 28 - Mon, Feb 2
United Airlines Logo
4:10 pm - 10:53 pm
IAD
-
ONT
9h 43m1 stop
United Airlines Logo
1:53 pm - 12:59 am
ONT
-
IAD
8h 06m1 stop
$264United Airlines
Thu, Feb 19 - Tue, Mar 17
Delta Logo
3:42 pm - 9:05 pm
IAD
-
ONT
8h 23m1 stop
Delta Logo
10:25 pm - 9:10 am
ONT
-
IAD
7h 45m1 stop
$274Delta
Wed, Jan 28 - Sat, Jan 31
American Airlines Logo
5:26 pm - 10:48 pm
IAD
-
ONT
8h 22m1 stop
American Airlines Logo
10:58 am - 9:17 pm
ONT
-
IAD
7h 19m1 stop
$278American Airlines
Wed, Apr 22 - Mon, Apr 27
Delta Logo
11:00 am - 6:28 pm
IAD
-
ONT
10h 28m2 stops
Delta Logo
10:15 pm - 9:15 am
ONT
-
IAD
8h 00m1 stop
$279Delta
Mon, Jan 26 - Tue, Feb 3
Delta Logo
3:42 pm - 9:05 pm
IAD
-
ONT
8h 23m1 stop
Delta Logo
10:30 pm - 9:13 am
ONT
-
IAD
7h 43m1 stop
$287Delta
Thu, Jan 29 - Mon, Feb 2
United Airlines Logo
4:10 pm - 10:53 pm
IAD
-
ONT
9h 43m1 stop
United Airlines Logo
1:53 pm - 12:59 am
ONT
-
IAD
8h 06m1 stop
$291United Airlines
Booking Insights

KAYAK's insights & trends for Dulles Intl to Ontario flights

Get data-powered insights and trends into flights from Dulles Intl to Ontario to help you find the cheapest flights, the best time to fly and much more.

What is the cheapest month to fly from Washington, D.C. Dulles Intl Airport to Ontario?

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Washington, D.C. Dulles Intl Airport to Ontario, removes the top 0.1% to account for outliers, and then takes the median of all values for each month.

The cheapest month for flights from Washington, D.C. Dulles Intl Airport to Ontario is September, where tickets cost $273 (return) on average. On the other hand, the most expensive months are January and November, where the average cost of round-trip tickets is $774 and $661 respectively.

Good to know

Low seasonFebruary
Cheapest flight$88
Best time to beat the crowds with an average 2% drop in price.
Most popular time to fly with an average 43% increase in price.
Flight from Washington Dulles Airport to Ontario

When to book flights from Dulles Intl to Ontario

Are your dates flexible? Find out the best times to travel from Dulles Intl to Ontario based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price
KAYAK looks at all historical flight data for each date to provide a predicted price for one-way trips or round-trips with a duration up to 40 days. While we try to provide actual minimum prices for each date, some prices are predictions and actual prices may differ.

FAQs for booking Washington Dulles Airport to Ontario flights

  • What is the cheapest flight from Washington, D.C. Dulles Intl Airport to Ontario?

    In the last 3 days, the lowest price for a flight from Washington, D.C. Dulles Intl Airport to Ontario was $88 for a one-way ticket and $237 for a round-trip.

  • Do I need a passport to fly between Washington Dulles Airport and Ontario?

    No, a passport isn't needed to fly from Washington Dulles Airport to Ontario. However, local authorities might ask for an official ID.

  • Which airports will I be using when flying from Washington Dulles Airport to Ontario?

    Washington Dulles Airport and Ontario are both served by 1 main airport. You will leave Washington Dulles Airport from Washington, D.C. Dulles Intl and will be arriving at Ontario.

  • Which aircraft models fly most regularly from Washington Dulles Airport to Ontario?

    We unfortunately don’t have that data for this specific route.

  • Which airline alliances offer flights from Washington Dulles Airport to Ontario?

    SkyTeam, oneworld, and Star Alliance are the airline alliances operating flights between Washington Dulles Airport and Ontario, with SkyTeam being the most commonly used for this route.

  • Which is the best airline for flights from Washington, D.C. to Ontario, Southwest or Delta?

    The two airlines most popular with KAYAK users for flights from Washington, D.C. to Ontario are Southwest and Delta. With an average price for the route of $599 and an overall rating of 8.0, Southwest is the most popular choice. Delta is also a great choice for the route, with an average price of $371 and an overall rating of 7.9.

  • How does KAYAK find such low prices on flights from Washington Dulles Airport to Ontario?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from Washington Dulles Airport to Ontario.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Washington Dulles Airport to Ontario?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to Ontario from Washington Dulles Airport is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Washington Dulles Airport to Ontario?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly to Ontario with an airline and back to Washington Dulles Airport with another airline. Booking your flights between Washington Dulles Airport and ONT can sometimes prove cheaper using this method.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Washington Dulles Airport to Ontario?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying to Ontario from Washington Dulles Airport up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

Reviews of the top 5 airlines serving from Dulles Intl to Ontario

 
See real verified KAYAK customer reviews for airlines flying from Washington, D.C. to Ontario. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from Dulles Intl to Ontario? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
8.0
SouthwestOverall score based on 4248 reviews
8.1Boarding
8.6Crew
7.0Food
7.5Entertainment
8.0Comfort
Airline reviews

The flight crew was extremely rude and especially not helpful when our flight was delayed.

2.0 MediocreMatthew, Jan 2026
DAL - SAN
Read more Southwest reviews

The flight crew was extremely rude and especially not helpful when our flight was delayed.

Haven’t flown on SW in years. Flight was on time departing and arriving. Served vegan butter onion flavored pretzels which were bad. Coke served was in a tiny paper cup. Crew was not engaging. Felt like they were going through the motions. Old plane, tight seats and no leg room.

The boarding and seat assignment system no longer works for me, but I know it is being replaced. Otherwise, I am good with the overall experience.

The lead steward kept singing about "San Francisco" and hotel California---more annoying than humorous....needs work. Flight was smooth and on time.

Still a fan of open seating. Flight was on schedule and arrived on time. The 737 MAX is very comfortable.

No delays and arrived to destination 30 min early. Staff was super friendly.

San Diego airport is brand new, spacious, airy and very smooth checkin at SW baggage drop.

Ever since Southwest starting charging for bags, passengers don't want to pay to check their bags, so the gate agents have to beg people to check their roller bags now because there's "not enough space". This was a terrible business move by Southwest.

Delays delays delays. Late taking off, late landing, wait for a gate, etc.

Connecting flight is on time and boarding was a breeze!

I really liked the legroom. I am 6’4”.a at For some reason our seats were not together and using the app to fix it didn’t work. Passengers were nice enough to move for us but you should absolutely ensure a parent sits with their child.

This flight was no comparison to our prior flight. I'm thinking it all has to do with the age of the aircraft.

2 of the seats in row 31 the entertainment system was not working, and one seat the tray table did not go all the way down. Flight arrived early and departed on time which was great.

Waited at the usual crowded gate at DCA where one ends up standing up because there aren't enough seats.

Staff were friendly and happy. Delta could make sure passengers that don't have the app know of changes. Without Kayak I would not have known about the change of gate or the delay. Kayak was faster to notify me.

They changed planes and the new plane couldn’t carry enough fuel to fly across the country so we had to stop in Kansas City to refuel. Flight was delayed .

Flight was too crowded and seats are too small, especially since passengrs are getting larger. Having a middle seat is ALWAYS tough! Woman on my left was large & kept creeping in to my space. Flight personnel were great! Have more savory rather than sweet snacks please.

The crew took good care of us. The flight from ATL to SFO is a longer one, and there were multiple beverage offerings. I like the 757's that Delta uses. Good airplane that is comfortable. I do wish Delta would separate Priority boarding from the better seats. I would gladly take a smaller seat in an open row than be jammed into Comfort just to get priority boarding, just to make sure I don't have to check a bag.

Gate agent rushed to fill hot jetway with crowd so it took over 12 minutes to go from gate to plane. Just like a discount airline Pooly prepared cabin and third time that claim of rough air prevented any cabin service. Friends on a Southwest flight at similar time had service.

I was uncomfortably cold on the plane. Other than that it was uneventful and therefore as enjoyable as a plane ride can be.

Sat next to a one year old. She crawled all over the place and made me laugh.

The Crew and the food was the worst I ever had in Business Class. First they told us there were no space for carry on. It was plenty of space over our 2 row seats, we had to ask to let us travel with it which was accepted. They were aware that we had to run for the connection due to the previous flight delay. Have us one hour waiting for more customers and not even offer a glass of water. Then started the service and they started to serve other passengers drinks in business and did not offer any drinks until they serve our pre ordered meal and I ask for something to drink. I had to wait until they finished to serve all passengers until Inget something. The crew was the worts I ever had for Business Class in my life.

Not great experience - we were super late boarding due to issues with aircraft. Then when we finally all got onboard and seated and they started taxiing out to the runway they just stopped then turned around and went back to the airport. Apparently the crew “ran out of time” to legally fly us. They mentioned that they were about 2 minutes away from taking off. I understand the rules and safety but kinda wonder why they would have bothered boarding us in the first place? Had to go all the way back and de plane and then wait in a HUGE line to get a hotel (this is somewhere around 2:30am) finally got to hotel by Uber (no shuttle after 20min so gave up) and they ended up putting us all back on the same aircraft at 10am next morning so got about 2.5 hours sleep. They did give us. $250 credit, but it was a São Paulo Brazil flight out of Dulles. The flight and everything was fine.

Starlink wifi on the Embraer E175 is an excellent experience. I was able to connect and work from IAD all the way to approach into BTV.

7 hours delayed due to operational issues on United’s end. Basically laziness.

Short flight but an "eager to help" crew made the journey more enjoyable!

During booking, I kept trying submitting my payment from the Mexican website and it didn't work. After I had the idea to change it to the Canadian website, it worked but I had to be charged the equivalent of 50 CAD more. I received the clear instruction that I would only be able to check-in at the airport and that it was impossible to select a seat 24 hours before departure, that I had to pay 144 CAD to do so, although not only was I able to check-in 24 hours before departure, but I could have selected my seats for free then. All in all, I almost threw $200 out the window due to misleading information. Besides, the app kept crashing, the information to get to the gate on the app was inaccurate, my gate was switched and I was only informed once in the air (luckily I had noticed the departure pannel), I was not addressed in my language beforehand and even if I tried I was immediately answered in English (which meant the crew understood but didn't want to answer accordingly), there was only one snack & beverage service on my medium haul flight and no beverage service on my short haul flight. To be fair, the planes were comfortable, the crew apart from the language issue was helpful, dynamic and engaging, the plane was clean and the directions were clear and direct. United has a lot of potential to be one of my favourite airlines, but the devil is in the details and a lot of them missed the target.

Better WiFi. I cannot understand that in 2025, United is so behind on a technology that is now a necessity and still painfully unreliable, slow and keeps disconnecting.

Great service on board. Boarding a bit slow due to process. Food was pretty average.

Very small cramped plane for an international flight. Everything else was good, but it was maybe the smallest comfort-wise I've ever been on for longer than 3-4 hours and the trip was 7.5

After the door had been closed, the cockpit makes an announcement that catering is running late and it is not the airline's fault. It is their fault in the sense that we had to sit for 2 hours or more when we could have stayed in the terminal. Poor communications between catering and airline. This caused a young man to lose his temper and he went storming out hitting objects. He had complained to the gate agent that he had already waited at the gate 7 hours and when can the airplane leave? Airilnes do a poor job of explaining delays, maintenance issues, etc. whereas being truthful may gain more sympathy or understanding.

delayed due to weather. Could not communicate with family since the wifi was broken

I got sick nothing contagious but distressing and the care I received by Kayla? Keighly the flight attendant will be memorable for ever. Thank You

We were told the flight was delayed 5 times, then it was moved to the next day.

The experience with American Airlines was good, although the Philippines Airlines flight was much better (better seats, better food, better entertainment options, overall better). Again, the MIA to LAX flight was fine, but nothing in comparison to the comfort and accommodations of the Philippines Airlines flight from LAX to MNL.

Loved the crew . Absolutely no complaints. Except for luggage lost

Flight delay was communicated before leaving for airport which caused it to be a non-event. Great flight and crew!

The flight attendant, a black woman with curly hair who sat near Row 21, was wonderful and kind.

It took way too long to diagnose and solve the problem of a broken crew member cabin seat. Though compensation for the volunteer who left the flight was very kind.

We fly American Airlines quite a bit. And we always fly business class when traveling internationally. We were a bit disappointed with the comfort of this particular plane as well as the entertainment options.

It was ok. It was expensive to check 2 bags ($75.00 per bag), and then it took a long time to wait for shuttle to take us from one terminal to the terminal where the plane was taking off at LAX. And all of this for a flight where we had to pay for any food or drink that was not water.

It didn’t happen. I booked it and then was told it wasn’t available and then forced to pay far higher prices for a worse option

A 630departure flight Delayed 6hours! They changed my gate, I moved to the new gate. Had our flight on the screen for 12noon departure. I go get above to eat, check screen again and the flight was gone, no notice no announcement, nothing!! They sent my bag on the flight I wasn’t on, got it back to me 3days later. Thank goodness they did refund my money but I will NEVER fly them again.

Due to weather, my flight was delayed, further delayed, then canceled. I eventually got through to a support person who helped me find a different route out of MSP, but to get to DIA, they didn't want to, but eventually did help with the connection ticket purchase. But even this replacement flight was delayed time and time again, and I would have missed my connecting flights and I didn't want to get stuck in a layover city, so after 12 hours at the airport with two young boys who were very tired, we just cancelled our plans and spent the week at home, instead of Nana's.

Plane and crew on board were fine. Everything else was terrible.

The third party booking with cheapflightsfares was awful. Kayak should NOT partner with them. They sold me a bundle including seat selection and carry-on, but did not book the carry-ons with Frontier, so I’m out of pocket for $414 more while I await resolution.

This company socks. It's fraud. They canceled our flight yesterday, and today we were late because of a really long line at the check in bag. At the rebook station, there was ton of people. The workers were all rude. I am gonna make a report to FTC.

One of the worst travel experiences I've had. Had a flight scheduled with CVG to RSW on VLSWQX this morning departing at 5:30. Two individuals at the gate and one was in training. Not her fault but she didn't have the ability to check people in resulting in at least 15 families that didn't make it on the plane because they weren't checked into the system in time. When arriving at the airport to drop off our prepaid checked bags, the bag drop off agent asked if we could check our bags at the gate because of the long line. We said no problem so arrived at the gate by 5:00. They told those people that had previously paid for checked bags to stand off to the side while they let others that either didn't have a checked bag or their bag was already on the plan through. Realizing the gate workers had an issue, they either called for help or this lady showed up late for work as she didn't arrive until 5:15. The worker who had been there training the other individual and working diligently to make sure all passengers got on board. He even said that at one point all people that are currently in line are fine but asked the person in training to stand outside the ticketing area around 5:15 to notify any late travels that the flight was in boarding process and they arrrived too late. At that point, we're sill standing off to the side with our pre-paid checked bags patiently waiting. When the new lady arrived she couldn't have been more rude. It was an awful seen. Essentially they had asked for those without an assigned seat to board last, those with pre-paid checked bag stand off to the site and any traveling with a larger items that needed to be checked at the gate (such as a stroller), wait on the side. They realized that the flight needed to leave on time so the gate attendant shut the gate. So anyone without a seat assignment, those that had pre-checked bags, and the worst one I saw was a mother with two infant children was in line with use because she was asked to stand to the side because her stroller. When they shut the door to the plan they told her she could no longer get on. Her checked bags were already on the plane with her car keys in them, and the lady told her we couldn't accept anyone else on because the door was shut. She didn't even have a way to get home from the airport. Truely evil behavior. I've flown Frontier enough to know customer service is not a top priority in the company's mission, but this was an all-time low. I'm sending this after an 18 hour drive that our family just completed to Bonita Springs . I felt really bad for the lady being trained and the other individual trying to help, but when the new lady came to the gate she was truly one of the rudest individuals I've ever met. One lady had been there since 4am but because she didn't have an assigned seat they wouldn't let her on the plan.

I loved the staff on the plane. So friendly and helpful! However, there was an argument and misunderstanding by the staff and a customer at the gate, and the staff member was being unprofessional. When we arrived in Atlanta, we waited 1.5 hrs for our luggage to arrive. When I asked the airport attendant, they said Frontier had the longest wait for luggage out of any airlines, and that they could not be held responsible for the delay.

Not clean and was told I would get a great seat and it was not great at all

Everything you need to know for your flight from Dulles Intl to Ontario

Information on your arrival and departure airports