$45 Find Cheap Flights from Ontario to the United States - Compare and Save

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Ontario to the United States departing on 8/17. 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

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Cheap Flights from Ontario to the United States

Cheapest round-trip prices found by our users on KAYAK in the last 72 hours
New York
New York1 stop$311
Los Angeles
Los Angeles1 stop$125
Las Vegas
Las Vegasnonstop$94
Chicago
Chicago2 stops$283
San Francisco
San Franciscononstop$105
Miami
Miami1 stop$244
Boston
Boston1 stop$252
Fort Lauderdale
Fort Lauderdale1 stop$264
Washington, D.C.
Baltimore1 stop$239
Denver
Denvernonstop$127
Seattle
Seattle1 stop$188
Atlanta
Atlanta1 stop$340
Dallas
Dallasnonstop$255
Tampa
Tampa1 stop$242
Houston
Houstonnonstop$173
San Diego
San Diego1 stop$125
Honolulu
Honolulu1 stop$432
Philadelphia
Philadelphia1 stop$299
New York
New York1 stop$311
Los Angeles
Los Angeles1 stop$125
Las Vegas
Las Vegasnonstop$94
Chicago
Chicago2 stops$283
San Francisco
San Franciscononstop$105
Miami
Miami1 stop$244
Boston
Boston1 stop$252
Fort Lauderdale
Fort Lauderdale1 stop$264
Washington, D.C.
Baltimore1 stop$239
Denver
Denvernonstop$127
Seattle
Seattle1 stop$188
Atlanta
Atlanta1 stop$340
Dallas
Dallasnonstop$255
Tampa
Tampa1 stop$242
Houston
Houstonnonstop$173
San Diego
San Diego1 stop$125
Honolulu
Honolulu1 stop$432
Philadelphia
Philadelphia1 stop$299

Book Cheap Ontario to the United States Plane Tickets

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Ontario to the United States 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 Ontario to the United States

Thu, Sep 24 - Mon, Sep 28
Frontier Logo
2:26 pm - 3:56 pm
ONT
-
SFO
1h 30mnonstop
Frontier Logo
12:31 pm - 2:00 pm
SFO
-
ONT
1h 29mnonstop
$105Frontier
Thu, Sep 24 - Mon, Sep 28
Frontier Logo
2:26 pm - 3:56 pm
ONT
-
SFO
1h 30mnonstop
Frontier Logo
12:31 pm - 2:00 pm
SFO
-
ONT
1h 29mnonstop
$106Frontier
Sat, Sep 12 - Wed, Sep 16
United Airlines Logo
8:00 am - 9:27 am
ONT
-
SFO
1h 27mnonstop
United Airlines Logo
10:37 am - 12:12 pm
SFO
-
ONT
1h 35mnonstop
$117United Airlines
Wed, Aug 19 - Sat, Aug 22
Southwest Logo
12:30 pm - 5:35 pm
ONT
-
HOU
3h 05mnonstop
Southwest Logo
8:25 am - 9:35 am
HOU
-
ONT
3h 10mnonstop
$235Southwest
Wed, Jul 15 - Wed, Jul 22
Southwest Logo
12:05 pm - 8:05 pm
ONT
-
HOU
6h 00m
1 stop
Southwest Logo
9:25 pm - 10:35 pm
HOU
-
ONT
3h 10mnonstop
$245Southwest
Sat, Aug 1 - Tue, Aug 4
United Airlines Logo
1:18 pm - 10:49 pm
ONT
-
ORD
7h 31m
1 stop
United Airlines Logo
8:18 pm - 10:51 pm
ORD
-
ONT
4h 33mnonstop
$289United Airlines
Fri, Aug 21 - Sun, Aug 23
American Airlines Logo
12:59 pm - 11:58 pm
ONT
-
JFK
7h 59m
1 stop
American Airlines Logo
6:54 am - 1:31 pm
JFK
-
ONT
9h 37m
1 stop
$312American Airlines
Fri, Aug 21 - Sun, Aug 30
American Airlines Logo
12:59 pm - 11:58 pm
ONT
-
JFK
7h 59m
1 stop
American Airlines Logo
6:54 am - 11:43 am
JFK
-
ONT
7h 49m
1 stop
$317American Airlines
Thu, Nov 12 - Sun, Nov 15
Alaska Airlines Logo
5:52 pm - 5:58 am
ONT
-
EWR
9h 06m
1 stop
Alaska Airlines Logo
7:00 am - 4:58 pm
EWR
-
ONT
12h 58m
1 stop
$368Alaska Airlines
Wed, Oct 21 - Tue, Oct 27
Alaska Airlines Logo
2:13 pm - 11:54 pm
ONT
-
HNL
12h 41m
1 stop
Alaska Airlines Logo
12:27 pm - 9:01 pm
HNL
-
ONT
5h 34mnonstop
$434Alaska Airlines
Booking Insights

KAYAK's insights & trends for Ontario to the United States flights

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

What is the cheapest Ontario to the United States flight route?

Data is based on round-trip flight searches on KAYAK over the past month.

The cheapest ticket to the United States from Ontario found in the last 5 days was to San Francisco, at $95 round-trip. The most popular route is from Ontario (ONT) to Dallas/Fort Worth Airport (DFW), and the cheapest round-trip airline ticket found on this route in the last 5 days was $281.

What is the cheapest time of day to fly to the United States?

The average price for all round-trip flights from Ontario to the United States depending on the time of departure, clicked by users on KAYAK in the last 2 weeks.

The cheapest time of day to fly to the United States is generally at night, when round-trip flights cost $410 on average. The most expensive time of day to fly to the United States is generally at night, which is peak travel time and where the average cost of a ticket is $410.

Can I save money by flying with a layover from Ontario to the United States?

The average round-trip price for all non-stop flights, flights with one layover, and flights with two layovers for the route found by users searching on KAYAK in the last 2 weeks.

No, with an average price for the route of $377, prices are generally cheapest when you fly direct.

What is the cheapest month to fly from Ontario to the United States?

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Ontario to the United States, 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 Ontario to the United States is August, when tickets cost $279 (return) on average. On the other hand, the most expensive months are June and March, when the average cost of round-trip tickets is $411 and $392 respectively.

What’s the cheapest day of the week to fly from Ontario to United States?

The average price of all round-trip flights from Ontario to the United States clicked on KAYAK for each day over the last 12 months.

When flying from Ontario to United States, you should consider leaving on a Sunday and avoid Wednesdays if you are looking for the best rates. For your return to Ontario, you’ll find the best rates on Tuesdays and the most expensive ones on Mondays.

How far in advance should I book a flight from Ontario to the United States?

To calculate weekly average prices, KAYAK takes all prices for each week before departure over the last year for round-trip flights from Ontario to the United States, removes the top 0.1% to account for outliers, and then takes the average of all the values for each week.

To get a below average price on the flight from Ontario to the United States, you should book around 3 weeks before departure, which saves you about 30% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 19 weeks before departure.

Good to know

Low seasonJanuary
Cheapest flight$45
Best time to beat the crowds with an average 3% drop in price.
Flight from Ontario to San Francisco

Flights from Ontario to the United States: the best tips from KAYAK users

Insights shared by verified travelers who flew the route from Ontario to the United States 
Verified travelerFlew with Alaska Airlines
ONT
-
PDX
Mar 2026
TSA security isn’t bad, sometimes gets crowded right before another flight goes out. Smaller airport but has many flight options.
AdrianaFlew with American Airlines
ONT
-
PHX
Apr 2026
Check on your flight status often, as things can change and you may not be notified promptly
Verified travelerFlew with United Airlines
ONT
-
SFO
Feb 2026
1 hr is doable if you're transferring at sfo but probably just get something to go food wise
FraxysFlew with American Airlines
ONT
-
DFW
Jun 2025
Bring an empty refillable water bottle/container through TSA and fill it up as soon as you pass the security check. The water station is available to the left and to the right of it.
Verified travelerFlew with Frontier
ONT
-
LAS
Dec 2024
Pack light and arrive earlier.. Also download the App and check your flight and check in..
LeoFlew with American Airlines
ONT
-
CLT
Sep 2024
Have plenty of patience for the casual travelers! They are oblivious of rules and etiquettes that slows down the process for everyone. Case in point, a guy held up the line trying to place both his personal item (should be UNDER the seat in front of you) and his carry on case horizontally. Obviously not aware of the big poster right in front of his displaying the proper way of placing his case on it's side. Slowed the whole line of people behind him. Also be mindful the agents in Ontario airport (or any smaller airports) might not be the most knowledgeable on the rules and regulations of air travel, luggage specification allowances etc. Stay patient!! Also the seats do not recline that well anymore on AA flights. So if you have back problems, be sure to bring some back supports.
Verified travelerFlew with Alaska Airlines
ONT
-
PDX
Oct 2024
Portland is a big airport, give yourself time.
MariFlew with American Airlines
ONT
-
CLT
Jan 2024
Bring a blanket it's very cold on plane

FAQs - booking United States flights

  • How does KAYAK find such low prices on flights from Ontario to the United States?

    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 Ontario to the United States.

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

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight from Ontario to the United States 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 Ontario to the United States?

    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 from Ontario to the United States with an airline and back with another airline.

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

    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 from Ontario to the United States up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

Top tips for finding cheap flights to the United States

  • Looking for a cheap flight? 25% of our users found tickets from Ontario to the following destinations at these prices or less: Denver $187 one-way - $293 round-trip; Dallas $197 one-way - $396 round-trip; Las Vegas $142 one-way - $202 round-trip

Reviews of the top 5 airlines serving from Ontario to the United States

 
Need help choosing which airline to fly with from Ontario to the United States? 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.
7.9
Alaska AirlinesOverall score based on 12582 reviews
7.0Entertainment
7.8Comfort
8.5Crew
8.1Boarding
7.0Food
Airline reviews

The first flight was fine, great crew, but the plane was delayed 45 minutes to go to Seattle because of they were missing a ramp. That would make sense if the plane was actually at the gate. Not if we’re still waiting for a plane. After we landed we waited 30-45 minutes on the tarmac just to get off the plane. Alaska made me miss my connecting flight, wasting my time, and my money. I should honestly be reimbursed, but hey, when does the airline ever actually take accountability? Never.

2.0 MediocreAnonymous, Jun 2026
ONT - SEA
Read more Alaska Airlines reviews

The first flight was fine, great crew, but the plane was delayed 45 minutes to go to Seattle because of they were missing a ramp. That would make sense if the plane was actually at the gate. Not if we’re still waiting for a plane. After we landed we waited 30-45 minutes on the tarmac just to get off the plane. Alaska made me miss my connecting flight, wasting my time, and my money. I should honestly be reimbursed, but hey, when does the airline ever actually take accountability? Never.

Wish there were more complimentary drinks available - only had water and apple juice. Also - no snacks were provided during the flight, but we were offered some items as we exited the plane.

My daughter has anxiety and became nauseous after boarding the plane and before take off. She went to the plane bathroom and ended up having to vomit, and your staff promptly removed us from the flight. We explained that it was due to my daughter’s anxiety, and that the condition would not continue in the air, but they removed us anyway. We have flown many many times before on many different airlines and my daughter’s anxiety has resulted in nausea and sickness before takeoff, and every airline has been accommodating and professional. This is was our first time flying with your airline, and also the first time we have ever been removed from a flight. This was the worst service we have ever experienced. This was a special surprise trip we gifted to my daughter for graduating college. I had also paid to upgrade the family to first class and sit all together which we had never done before and can’t afford on a normal basis. Our removal from the flight was not only extremely embarrassing, but devastating for my daughter. My daughter and I were removed from the plane and a call was made by your staff to medical personnel, a few questions were asked of my daughter, and then she was magically cleared. All of this took mere minutes. Why this could not have been performed while we were on the plane, or why this could not have been performed off the plane and then us allowed to reboard is beyond me. My wife and youngest daughter continued on the original flight alone and were very upset and crying due to the situation, yet the staff did nothing to console or assist them. My wife states that upon arrival in Portland and as they were exiting the plane, one of the stewardesses involved said “byyyyeeeee” to them sarcastically and laughed. Myself and my oldest daughter had to wait 4 hours for an alternate flight and were sat in regular seats because our first class seat purchase could not be honored. My wife wasn’t allowed to pick up our rental car and had to wait 4 hours with our luggage until I arrived. The delay prevented us from being able to carry out planned events and ruined the first day of our trip. Upon explaining all of this to your customer service, we received no sympathy, assistance, or compensation other than your staff submitting a request for a reimbursement of my and my daughters first class upgrade cost. When checking in early for our flight back home, the luggage cost for myself and my eldest daughter was no longer discounted as it was for my wife and youngest daughter. Customer service once again could not assist me over the phone and rectify what should have been a minor adjustment. Instead they stated I would have to wait until we physically checked bags in at the airport and then ask staff to adjust the luggage cost. With everything else we had experienced, I was not going to leave that to chance and instead paid full price for the luggage ahead of time. Or experience with Alaska Airlines was a complete disaster and I am baffled at the lack of empathy and assistance from your staff. I’m not sure of what else to say other than the fact that unless we are compensated by Alaska Airlines in some form to offset the horrendous service we received, we will be relaying our experience to family and friends and on social media, and doing all we can to urge everyone to avoid utilizing your services.

I got an email 3 hours before the flight letting me know it got canceled

Boarding was easy and quick. Staff was very friendly. Service of snacks and drinks by staff was outstanding.

It was ok! Not fond of sitting in middle seat. Tried to upgrade with my Atmos card but it was a new account and they weren’t able to look up my account details.

Not bad. Due to not buying a seat, on the way back, my seat was not assigned till 2 hrs before the flight left. Got me worried I wouldn’t have a seat.

There is no entertainment on the plane. The snack is minimal. The crew was nice and professional.

The first leg of the trip was excellent. Lovely flight attendants and comfortable plane. The second leg left a lot to be desired. The flight attendant was rude when I asked for a Diet Coke, the boarding required quite a long walk and the plane was crammed and uncomfortable.

You no longer give receipts for baggage at the counter. And it is next to impossible to get it on your webpage. Spent 20 min trying and gave up... I need receipt to submit for reimbursement and don't have time to waste on your poor webpage Disappointing .....

Flight was delayed, full flight and I had to change gates. Southwest flights are always late later in the day.

Was fine, delayed and feels like southwest is always late

The entire experience from boarding to landing was amazing! The crew were very friendly. Will definitely be back.

Delayed flight, lack of information, boarding process is a mess as is the carryon luggage causing issues when leaving the plane….just a poor experience.

Comfortable. Easy. No problems. Just wish they had gf options for snacks.

The crew was very kind and made going to Hawaii relaxing and fun to look forward to! Thank you Southwest for a pleasant flight!

Terrible. Even though there’s assigned seating now, they are still the slowest boarding airline of anyone.

It was good from LAX to Phoenix, But the connection in Phoenix to Tulsa was not that great. The staff on both flights were great. The choice of free entertainment was ok nothing to brag about. The 45 min delay because of some electrical issue wasn't great from Phoenix to Tulsa. We sat there with hardly any air, The seat I had was between windows so the side of the plane pushed in on you. My being a bigger man it then made the seating area uncomfortable. The seats on the plane had no power to connect to recharge your phone or anything. I would recommend that they should look into a slot or clamp to hold your phone to enjoy while watching the entertainment choices hands-free. Also make it possible to raise the inner seat by the window be able to raise the arm rest up to make more room for larger people to set more comfortably. I would also say other then that stop price gouging the airfare or nickel and diming everything. Not fair for people having to fly for emergencies and be paying for higher prices due to the season or holidays. Your making your money either way and the cost of flying is still going to be the same regardless if there's 100 people or 200 people.

Southwest was greaat! The most expensive but the least upsetting for those we were flying to see.

I liked receiving attention from aged and well experienced flight attendants. I disliked the non-gluten-free snack but I brought my own so I was OK.

Lost one piece of luggage even though I checked in 2.5 hours before the flight

The boarding process on the departure from LA was rather slow even though I was in Group 1. For first class, I was not expecting to have to pay for Wi-fi but I did and then the wi-fi was spotty. The entree was surprisingly good and so that was a pleasant surprise. However, once I got to Houston, it was terrible. Unfortunately there was bad weather but the constant gate changes for my connecting flight was difficult to manage due to having to navigate back and forth between different terminals.

Service was professional and quick. Premium economy seat was comfortable given the class

The staff was extremely helpful and friendly at all times! They went above and beyond to get us into an earlier flight in San Diego to make our connection in SFO possible, because our original flight did actually not make it! I did so much appreciate the UA team and how they made this possible. We also didn’t have seats together on the long flight to Singapore, but they found us seats together last moment with no additional cost! Nobody sat next to us, so that we were able to sleep! Thanks to UA for improving their service and Underpricer for booking this trip! Please be careful: 1,5 hrs for transfer in San Francisco might not be enough time in the future

Over 2.5 hour maintenance delay on first morning flight with no acknowledgement, compensation or even gesture of good will. Aircraft had overnighted at airport so issue should have been addressed prior to boarding. Over 3.5 hours before first slow and deliberate beverage service.

Horrifying Almost 2 million miles. Bring your own food and drink. One coffee or drink every three hours. Have to order meals on app more than 24 hours ahead Tiny and dirty bathrooms

Flight was delayed but more than 90 minutes. This caused me to miss my available windows for pick-up by a friend. I had to pay $125 for an uber back home from the airport which was an added expense that I had not budgeted for my trip. Staff was friendly.

Seat pitch is horrible especially on the 15 hour flight. Gate crew at SFO was Outstanding. The flight crew was also great.

My service dog and I were asked to deplane just before they closed the door - clearly very last minute they couldn’t find the documentation that I have filled out many many times before that is for flying service animals. I purposely purchase 3seats (a whole row) since he is large and not all passengers want to sit next to a dog on a cross country flight. The plane departed with my husband on it!!! They made me fill out a hard copy of the same form and had to reschedule me on a later flight where they could find 3 seats together!! I’ve done this so many times before - clearly the error was on their part in a technology glitch - but really people - do better!! Very traumatic - and my husband had to wait for us when he landed ….so bad. Poor pup was confused and tired.

Late plane. Only one crew on the ground so we b had to wait for Denver flight to come in, board, and depart. At 78 yrs of age I was not pleased trying to get my connection. What really made me angry was the notification you sent me to hurry up or I would miss my connection. Why tell me to hurry up when you got me in late. It was not a good way of treating customers.

Flight was delayed multiple times without giving any particular reason and the only thing that was communicated was that 'Aircraft is getting ready'. I was stuck at SFO airport for 15 hours and finally took Southwest Airlines flight back home to Dallas.

I was not clear if food was offered or not.

Agency very bad had to cancelled my booking too many changes in the flight changed my flight to 1 week

The gate experience at LAX was abysmal (same for the arrival experience two days prior). Despite the LAX -> SAT schedule of two flights daily, our departure gate was at a smaller hub that we had to be bussed to from Terminal 4. Fortunately, I arrived at LAX extra early and had time to spare, but if I had not known, I might have missed my flight. I looked at the LAX airport map in the AA app and there was no indication of the additional boarding process. Lastly the gate area we were bussed to was crowded with limited food and beverage options. On flight, the fight attendant was hospitable and attentive, the flight was smooth, and AA's free (and working) wifi for AA members were all on the positive side.

Ontario airport boarding was very easy to park and access, is clean and TSA took 10 minutes total. Check-in was a breeze and cruise was very nice.

Good flight, seated and had a water within 5 minutes. Crew was hospitable.

The flight was on time and arrived early. The crew were friendly and helpful.

The chair cushions may need an upgrade. I have been noticing they are so worn out, thin so you’d sit in a dip 😄. Other than that, all was an enjoyable trip. Thanks AA!

VERY disappointed at the agent checking in my luggage. I know that the weight limit is 23 kg, a little over 50 pounds (50.71 pounds). Yet the agent kept repeating "50 pounds". So I said, the limit is 23 kg, and she had the audacity to say 'no, it is 22 kg!" Imagine my surprise. Was she ignorant or was she poorly trained? Not sure. The boarding process was pretty good. The speakers were loud enough so I still could hear them despite inconsiderate passengers continuing to speak while the announcements were going on. During the flight, the teenage girl sitting behind me kept pressing her feet to the back of my chair. I turned around several times, yet she did not get the hint. I did not make a fuss since I sense I had a bad streak that night with AA, so I just did the best I can to lean forward and not let that bother me.

It was wonderful upgrading to first. Plane was so cold thou. Crew was great. Wish there was a food option in first for such a long flight. Doesnt matter the time of day. Chintzy.

They didn’t offer a water, even after I asked

The takeoff was the smoothest I've ever experienced on any airline and this is the first time I've flown on frontier so this was an extremely pleasant surprise!

A lady asked to stop the flight after the tunnel pulled away and we began to depart a flight that was already hours late. The attendance respectfully stopped the the plane and had the tunnel return. After the tunnel returned the passenger claimed to have changed her mind . The tunnel was then put in reverse and the passenger remained on the plane .. They should have sent the sick passenger off the plane like initially replaced. They existed a couple off the plane prior to that situation.. So.. all and all.. it was a long and flight.. .

We understand and comply with Frontier’s bag sizes. We’ve had some problems in past while having to await other passengers who do not understand the baggage restrictions or have not prepaid and that is usually our biggest concern (others delaying us) with flying Frontier. Flying OUT of ONT, however, has always been a great experience. I’ve also noted even on delayed Frontier flights very knowledgeable pilots who manage expectations well.

Long lines, rude staff, everything that's offered you have to pay for.

The last time I flew Frontier was in the 1960s when it was a “real” airline. We flew this time because of the price & schedule. As the saying goes, you get what you pay for.

I appreciated the upgrade to free cary-on bag and seat selection at no charge

Flight was delayed on the runway for 40 minutes the crew did not even offer even water to passengers to compensate for the flight delayed. The flight was delayed due to aircraft mechanical issues. Worst customer service ever

This isna terribly run airlines. If you're one minute late, they will deny your ticket. Don't waste your time or money

Flight was delayed for more than 3 hours, crew at ONT airport was rude, and when we got to DFW the airplane had an issue landing, we had to be taxied to the terminal, and the luggage was hold until the next day.

Everything you need to know for your flight from Ontario to the United States

Information on your arrival and departure airports