ONT

$39 Find Cheap Flights from California 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 to Ontario departing on 12/17. 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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Everything you should know

Cheapest round-trip
$57
Overall average: $70
Frontier
Wed 1/14Wed 1/21
LAS - ONT • Non-stop
Cheapest one-way
$39
Typical prices: $79-$154
United Airlines
Wed 12/17
SFO - ONT • Non-stop
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Flight Deals

Cheap Flights from California to Ontario

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

Wed, Jan 14 - Wed, Jan 21
Frontier Logo
4:45 pm - 5:54 pmLAS-ONT
1h 09mnonstop
Frontier Logo
3:07 pm - 4:19 pmONT-LAS
1h 12mnonstop
$57Frontier
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Mon, Jan 26 - Tue, Jan 27
Frontier Logo
1:30 pm - 2:41 pmLAS-ONT
1h 11mnonstop
Frontier Logo
3:07 pm - 4:19 pmONT-LAS
1h 12mnonstop
$58Frontier
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Tue, Jan 13 - Wed, Jan 14
United Airlines Logo
6:00 am - 11:18 amSMF-ONT
5h 18m1 stop
United Airlines Logo
6:00 am - 10:24 amONT-SMF
4h 24m1 stop
$161United Airlines
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Tue, Jan 13 - Wed, Jan 14
Southwest Logo
6:10 pm - 7:35 pmSMF-ONT
1h 25mnonstop
Southwest Logo
7:00 am - 8:35 amONT-SMF
1h 35mnonstop
$169Southwest
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Tue, Jan 20 - Wed, Jan 21
Southwest Logo
6:10 pm - 7:30 pmOAK-ONT
1h 20mnonstop
Southwest Logo
10:00 am - 11:30 amONT-OAK
1h 30mnonstop
$177Southwest
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Tue, Jan 20 - Tue, Feb 3
Delta Logo
9:48 am - 4:15 pmSMF-ONT
6h 27m1 stop
Delta Logo
5:10 pm - 11:45 pmONT-SMF
6h 35m1 stop
$179Delta
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Tue, Jan 20 - Thu, Feb 5
Delta Logo
5:12 pm - 11:58 pmSMF-ONT
6h 46m1 stop
Delta Logo
7:30 am - 9:51 pmONT-SMF
14h 21m1 stop
$182Delta
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Thu, Dec 11 - Mon, Dec 15
United Airlines Logo
7:00 am - 12:18 pmMRY-ONT
5h 18m1 stop
United Airlines Logo
6:00 am - 10:33 amONT-MRY
4h 33m1 stop
$219United Airlines
Find Deal
Fri, Jan 23 - Sun, Jan 25
American Airlines Logo
4:23 pm - 10:13 pmSTS-ONT
5h 50m1 stop
American Airlines Logo
9:59 am - 3:53 pmONT-STS
5h 54m1 stop
$237American Airlines
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Mon, Jan 19 - Sun, Jan 25
American Airlines Logo
12:55 pm - 6:20 pmSTS-ONT
5h 25m1 stop
American Airlines Logo
9:59 am - 3:53 pmONT-STS
5h 54m1 stop
$257American Airlines
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Good to know

Low seasonFebruary
Cheapest flight$39
Best time to beat the crowds with an average 11% drop in price.
Most popular time to fly with an average 12% increase in price.
Flight from San Francisco to Ontario

FAQs for booking flights from California to Ontario

  • How does KAYAK find such low prices on flights from California 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 California to Ontario.

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

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to Ontario from California 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 California 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 California with another airline.

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

 
Need help choosing which airline to fly with from California 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 4251 reviews
8.0Comfort
7.0Food
8.1Boarding
8.6Crew
7.5Entertainment
Airline reviews

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

10.0 ExcellentGordon, Nov 2025SAN - OAK
Read more Southwest reviews

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!

Very smooth checking in our luggage with a super pleasant SW agent. I enjoyed a fun entertaining movie.

First time traveling on Southwest since bag fees were implemented. Usual good service. Just more expensive now.

It was a perfect flight in all aspects! Both legs!

Boarding process, crew were good. But the seats were so uncomfortable that was all I could focus on. I literally had to sit forward so that all 3 of us could fit in row. I will try to avoid Southwest in the future for any flights over 60 minutes.

Great flight, 47 passengers on a 180 seat plane. Stewardess was pleasant and cheerful.

Great experience flying Southwest. The crew was really kind and helpful, and very friendly with our toddler.

Our flight from SFO to MSP was right on time on 11/15/2025. No delays. As we approached MSP at about 8 pm, we circled in the air until 8:40 pm so I don't call that efficient for MSP. I think the captain should announce the delay and why. (as if we all don't know that we are just circling around the area, slowing down, speeding up, slowing down.) Thank you. Marilyn Fischer

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.

The flight used a B767 with a very old interior from before 2014. The entertainment system did not work at all during the flight despite attempts to reset the system. It was like they flew this route just to be competitive.

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.

Food was surprisingly good but the WiFi was not great

My flight was extremely cold. I had a jacket and a cover was left in each seat. The cover was extremely thin and I have a disability, fibromyalgia and arthrithis and AC air is the worst. I closed my vent and my husbands vent and it still was frigid. I asked the attendant if I could get another cover and she quickly almost dismissively and totally unconcerned stating, (I quote) (one per chair) and walked off so quickly that I didn't get a chance to explain to her that I literally have adisability. I didnt want to make a seen so I set on that flight for over 5 hours in pain, joints locking up and extremely uncomfortable. When my fibromyalgia flares up my joints not only ache but they will lock up also and it takes me days to get back to my regular self even though I take medication for it. I felt like it would not have hurt anyone at all for her to just give me an extra cover because I'm sure they have all types of medical issues in people that fly every day.

United needs to step up their game. Delayed flight leaving Seattle, San Francisco. Older aircraft, not very comfortable.

Plane boarded early a quickly, was mostly full. We left close to on time. And landed early.

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

Flight was timely, relatively comfortable, with decent entertainment and food served. Only problem encountered was with the free messaging which I highly appreciate, but it did not work from iphone to non-iphones.

The internet service I paid for didn’t work at all and the flight crew was not very friendly.

Subject: Formal Complaint: Discriminatory and Unprofessional Conduct – Request for Immediate Action & Compensation Dear [Airline Customer Relations Team], I am writing to file a formal complaint regarding my recent travel experience with [Airline], which was by far the worst I have ever encountered. What occurred was not only unprofessional, but in several instances discriminatory, unsafe, and unacceptable. On the first leg of my trip, I arrived only four minutes past check-in. Instead of making any attempt to resolve the matter, your representative flatly denied me boarding and made me wait while she attended to passengers who arrived after me. By the time a manager intervened, it was too late to board, costing me time, money, and unnecessary frustration. The second leg of my trip (Chicago–San Francisco) raised even more serious concerns. From the outset, it was apparent that the staff—particularly two attendants—prioritized Caucasian passengers while dismissing African American and minority passengers. • When a Caucasian passenger in the exit row refused to comply with federal safety requirements, I, as a first responder, immediately offered to switch seats and assume the responsibility. My offer was blatantly ignored, and instead, a Caucasian passenger seated further up was chosen. This was discriminatory and deeply insulting, especially as I was actively de-escalating the situation that could have delayed the flight further. • During a lengthy tarmac delay of over 90 minutes, passengers were given conflicting and unreasonable instructions that created unnecessary distress and tension. • Throughout the flight, a visibly intoxicated passenger directly in front of me was disruptive, rude to others, failed to comply with seatbelt and electronic device rules, and yet faced no enforcement from the crew. In stark contrast, I was singled out for repeated compliance checks even though I was following every rule. This unequal treatment was so obvious that multiple passengers around me spoke up in my defense. This pattern of behavior demonstrated a clear lack of professionalism, disregard for passenger safety, and discriminatory treatment. I expect far better from an airline of your stature. As a paying customer subjected to this unacceptable treatment, I am formally requesting: 1. A full investigation into the conduct of the staff on both flights. 2. A written apology acknowledging the discriminatory and unprofessional behavior I endured. 3. Appropriate compensation for the distress, inconvenience, and mishandling of my travel. If this matter is not addressed promptly and thoroughly, I will have no choice but to escalate my complaint further, including filing with the U.S. Department of Transportation and sharing my experience through other channels. I trust [Airline] will take this complaint seriously and provide a timely resolution.

Check in was quick and easy during early hours. Flight was on time, and customer services was a plus.

The flight was comfortable with the exit row and great service

Plane was crowded and even when we hit altitude, the plane was hot, not enough air flow.

1. when we went to check in, our 2 first class seats had been CANCELED and the flight was sold out. This was done without our prior knowledge. It was all we could do to restore one first class seat for my wife and I flew economy. 2, Our flight home was scheduled to leave at 10:30 pm. Due to tsunami warnings, the roads were closed and our flight status was uncertain as to whether it would leave as scheduled. It was announced that it would now leave at 11:20 pm and the roads were now open since the tsunami had come and gone. We made a mad dash to the airport and checked in. Delays were announced at 12:30 pm, 1:30 am, 2:30 am and at 3:30 am it was canceled. Since this was a flight due to natural (tsunami) causes, there was no compensation. We were told to return at 1:00 pm the next day and our baggage would be kept on the plane since the same plane was going to leave at 1:00 pm. We had to return to our hotel for the rest of the night. The same plane did not leave at 1:00 pm and our baggage was gone! All in all, it was a miserable performance by UA. Information was hard to obtain and no one knew what was going on and what was going to happen. Hundreds of passengers slept on the floor, chairs, etc. No food and no water was made available to the passengers. It was a situation where UA could care less what was going on. As a one million mile flyer, I had not experienced anything like this before and it was hugely disappointing!

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

Wish some foods provided rather than just biscuit/cookie for flight more than 2 hours

We are too tired and frustrated to comment politely at this point

The flight crew was rude. We were in first class and no one even offered water until an hour after we were in the air. Horrible experience

Great. Quick and quiet and east. The breakfast choices were a welcome surprise!

The stewardess hit me with the food kart twice on the head and didn't say I'm sorry once. The same stewardess gave me a warm Apple Juice with No ice. The Flight was delayed for Departure 6 times, starting from 2:36pm, finally taking off 7:50pm. I was late picking up my child from the sitter by 3 hours.

Did not get the seat I selected and paid for.

My flight was delayed for several hours. Sitting at gate 16 for several hours, I got a text from Kayak the gate changed to 9 before it was announced. Very bad communication at each gate from American Airlines employees. I received 10 notifications of delay from Kayak. My vacation started off horrible! I will write to American Airlines corporate office also.

When I wanted to check in 3 hours prior to boarding time, the employees mentioned “a little over an hour delay” so I waited for an hour then I went to go look for food in the terminal and most people from that flight were in the same area looking for food. Finally I decided after food to check to see if it’s anytime closer and now it’s 2 mins until boarding closes?! What are you kidding me? I didn’t receive anything via sms about boarding now nor via email or on the intercom. I luckily made it through, barely, and then there’s no room for my carry on mind you I’m in the very first row so I had to place my purse in one further row back and my carry on sections down. Not sure who pays for better seats to get your stuff placed all over the plane but that was the worst experience I’ve ever had flying with anyone.

Terrible. The canceled my entire flight when I requested a refund for a trip frontier canceled trip one way.

i was unable to check in the flight. refund requested

I think Frontier was very good at communication. Their app worked very well. Loading was great and the flight was nice and easy.

This airline sucks. They offer low rates then charge you for everything, the app does not work well, the seats are the most uncomfortable. Maintenance issues on the flight, and you still have to sit through their credit card commercials. People are nice enough but does not make up for overall poor experience.

Great for the price. No wifi or entertainment, but gate agents and crew were fantastic and we boarded quickly and left on time.

Decent clean onboard experience. Okay discount airline experience. Unfortunately, any customer service interactions are difficult and unhelpful. There is no service. Also, a premium seat only gets you premium boarding if you line up first. Once they start general boarding you must go to the back of the line. Not very premium

The crew was mostly okay. The flight attendant who answered our questions was curt and unhelpful unfortunately. He seemed upset and I understand having off days.

Very bad! No good service delayed my second connection flight

They canceled flight. Hard to believe there was even a plane incoming for us to get on

Everything you need to know for your flight to Ontario

Information on the airport you'll fly into in Ontario