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STL - ONT

$45 Find cheap flights from St. Louis 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 St. Louis to Ontario departing on 5/8. 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
0 bags
Sa 5/25
Sa 6/1

Search 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 St. Louis 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 St. Louis to Ontario, as well as popular online travel agencies
In the last 7 days travelers have searched 44,979,812 times on KAYAK, and here is why:

Save 22% or moreCompare multiple travel sites with one search.

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Cheap flight deals from St. Louis to Ontario (STL-ONT)

Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from St. Louis 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 and deals for you by selecting your travel dates.
Choose your dates
4:39 pm - 10:00 pmSTL-ONT
7h 21m1 stop
2:25 pm - 9:36 amONT-STL
17h 11m1 stop
$87Frontier
Find Deal
Mi, Mai 15 - Di, Mai 21
4:39 pm - 10:00 pmSTL-ONT
7h 21m1 stop
12:59 am - 1:09 pmONT-STL
10h 10m1 stop
$88Frontier
Find Deal
Mi, Mai 15 - Mo, Mai 20
8:00 am - 11:47 amSTL-ONT
5h 47m1 stop
6:45 am - 4:17 pmONT-STL
7h 32m2 stops
$349American Airlines
Find Deal
Mi, Mai 22 - So, Mai 26
8:00 am - 11:47 amSTL-ONT
5h 47m1 stop
12:53 pm - 10:59 pmONT-STL
8h 06m2 stops
$369American Airlines
Find Deal
Do, Mai 16 - Di, Mai 21
2:30 pm - 10:38 pmSTL-ONT
10h 08m2 stops
5:00 pm - 12:57 amONT-STL
5h 57m1 stop
$398Delta
Find Deal
Mi, Jun 26 - Mo, Jul 1
12:39 pm - 4:59 pmSTL-ONT
6h 20m1 stop
10:15 am - 11:56 pmONT-STL
11h 41m2 stops
Sa, Mai 11 - Di, Mai 14
3:27 pm - 10:47 pmSTL-ONT
9h 20m1 stop
10:00 pm - 8:54 amONT-STL
8h 54m1 stop
$425Delta
Find Deal
Do, Mai 23 - Do, Mai 30
5:35 pm - 11:55 pmSTL-ONT
8h 20m1 stop
7:00 am - 11:59 pmONT-STL
14h 59m2 stops
Fr, Mai 10 - Mo, Mai 13
5:25 pm - 11:04 pmSTL-ONT
31h 39m2 stops
6:00 am - 10:14 amONT-STL
26h 14m2 stops
$566United Airlines
Find Deal
Fr, Mai 10 - Mo, Mai 13
1:37 pm - 11:04 pmSTL-ONT
11h 27m2 stops
8:50 pm - 3:41 pmONT-STL
16h 51m2 stops
$674United Airlines
Find Deal
Mi, Mai 22 - So, Mai 26

Flights from St. Louis to Ontario - Travel Insights & Trends

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

What’s the cheapest day of the week to fly from St. Louis to Ontario?

The average price of all flights from St. Louis to Ontario clicked on KAYAK for each day over the last 12 months.
When flying from St. Louis to Ontario, you should consider leaving on a Thursday and avoid Fridays if you are looking for the best rates. For your return to St. Louis, you’ll find the best rates on Saturdays and the most expensive ones on Mondays.

What is the cheapest month to fly from St. Louis to Ontario?

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for flights from St. Louis 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 St. Louis to Ontario is August, where tickets cost $199 on average. On the other hand, the most expensive months are June and April, where the average cost of tickets is $555 and $464 respectively.

How far in advance should I book a flight from St. Louis to Ontario?

To calculate daily average prices, KAYAK takes all prices for each day before departure over the last year for flights from St. Louis to Ontario, removes the top 0.1% to account for outliers, and then takes the average of all the values for each month.
To get a below average price on the flight from St. Louis to Ontario, you should book around 1 day before departure. For the absolute cheapest price, our data suggests you should book 37 days before departure.

Which airlines provide the cheapest flights from St. Louis to Ontario?

The cheapest price for the route for each airline clicked by KAYAK users in the last 72 hours.
In the last 72 hours, the cheapest one-way ticket from St. Louis to Ontario found on KAYAK was with Frontier for $45. Frontier proposed a round-trip connection from $87 and American Airlines from $349.

Good to know

Low season

August

High season

September

Cheapest flight

$45
Best time to beat the crowds with an average 46% drop in price.
Most popular time to fly and prices are also 27% lower on average.
Flight from St. Louis to Ontario

When to book flights from St. Louis to Ontario

Are your dates flexible? Find out the best times to travel from St. Louis 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 flights from St. Louis to Ontario

  • What is the cheapest flight from St. Louis to Ontario?

    In the last 3 days, the lowest price for a flight from St. Louis to Ontario was $45 for a one-way ticket and $87 for a round-trip.

  • Do I need a passport to fly between St. Louis and Ontario?

    No

  • Which airports will I be using when flying from St. Louis to Ontario?

    St. Louis and Ontario are both served by 1 main airport. You will leave St. Louis from Lambert-St Louis and will be arriving at Ontario.

  • Which aircraft models fly most regularly from St. Louis to Ontario?

    The Airbus A320neo is the aircraft model that flies most regularly on the St. Louis to Ontario flight route.

  • Which airline alliances offer flights from St. Louis to Ontario?

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

  • Which is the best airline for flights from St. Louis to Ontario, Delta or United Airlines?

    The two airlines most popular with KAYAK users for flights from St. Louis to Ontario are Delta and United Airlines. With an average price for the route of $426 and an overall rating of 8.0, Delta is the most popular choice. United Airlines is also a great choice for the route, with an average price of $621 and an overall rating of 7.4.

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

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

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to Ontario from St. Louis 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 St. Louis 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 St. Louis with another airline. Booking your flights between St. Louis 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 St. Louis 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 St. Louis up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

See more FAQs

Top 4 airlines serving from St. Louis to Ontario

 
See real verified KAYAK customer reviews for airlines flying from St. Louis 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 St. Louis 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
DeltaOverall score based on 10975 reviews
8.0entertainment
8.6crew
7.4food
8.2boarding
7.9comfort
Airline reviews

There was a loud squeaky sound the whole time we were flying.

6.0 GoodEliza, Apr 2024SAN - LAX
Read more about Delta reviews

There was a loud squeaky sound the whole time we were flying.

Had a broken tray in business class. Crew just shrugged it off.

I didn’t like that I could not select my seat and was assigned a seat when I checked in at LAX

Great experience overall. Check in at Austin was congested as they only have about 6 check in kiosks, one was broken, and there was a lot of Spring Break travelers.

Bag drop off was slow and annoying. Only 2 agents at the entire delta desk, and no one directing traffic for what line to be in, many confused people slowed down the process. Boarding was fine. Seats in Delta comfort plus were fine. Snacks were great! Definitely a bonus. The entertainment system was awful — old, slow, not responsive, and completely unable to play games due to some kind of error. But on the other hand, thank you to Delta for the free WiFi. That made it better.

Everything was very good other than I had selected a specific seat when I booked the flight and they changed it once I checked-in the day before my flight. I was still in first class but lost my aisle seat for a window seat. Being tall, the aisle offers more comfort so I always select an aisle seat.

Flight diverted in SD. Later take off in Seattle by 1.3hrs

Crew was not friendly when I went to request a seat change.

Really impressive staff at airport and on plane, especially given how busy it was

The plane smelled like a sewer. Multiple passengers complained. It’s a safety and quality issue to clean these planes.

delay several times and wait extra long to board. no entertainment service because there are problem for some rows. always encounter some delays for the last flight of the day.

On time every leg of the journey and exceptional staff at counter, gate, and on board. I haven’t travelled in US for a long time and was genuinely surprised how pleasant this was.

This was a Lufthansa flight. Disappointing main meal. Very rough over Canada and arrival at FRA. IFE was almost unusable.

Too many fees (but that seems to apply to all airlines nowadays)

For a 22 minute flight all you expect is for it to be safe and comfortable

I was not able to buy food in the flight. They refer to include your Credit card in the APP, and if you are not from USA (i have a credit card form Canada) it is not possible

Over two hours wait to get wheelchair assistance from arrival to the departure gate for LA was unreasonable even though there appreared to be heavy demand.

Airline did not explain reasons why flight was delayed two hours. Explanations were badly needed and rarely provided. Problem seemed to clearly be the airline’s fault and not the fault of the weather or airport.

I was delighted that we were able to get on the 4:40 pm flight rather than our original booking at 6:55 pm!! Other than that, the flight was comfortable and landed early😊

The flight and crew were fine. The entertainment- the sound was so bad through the headphones I could barely understand it and it was a show I had seen before. The food might have been fine but having to have an account with united in order to access the app in order to pay for the food was rage inducing. I had entered my credit card info at home and logged in as guest but that wouldn’t allow the “wallet” tab to open in the app. And then the wifi was so bad that it took about 45 minutes to fully log in and get all the info working at which time I missed the food. You shouldn’t have to give your address, email and phone number in order to get a hamburger.

American Airlines continues to price it can provide the least comfortable passenger experience in the air. This legacy carrier rivals the budgets for both terrible seats and inadequate amenities. I am a 5’7” woman who is not wider than a coach seat (even on these narrow bodied aircraft). My 3.5 hour flight was terribly uncomfortable because the leg room is inadequate (my knees hit the seat on front of me even when it was not reclined); the seat barely reclines; and the foam padding is worn thin to the extent one can feel the metal supports of the seat. Add to this the fact that the aisle is super narrow, so that the drink cart literally scrapes the arm rest of the aisle seat. It’s basically torture.

Fight crew was not very attentive and the bastions were gross!

Our flight was great we left Kona earlier and got into LAX almost an 1hour earlier as well. LAX AA is in repair so to get out and found our bus to get pick up was a bit confusing.

Plane was good but was delayed. probably not AA fault but caused a 1 hour delay. Seating was cramped.

5 hour flight - full flight - not enough room to use my computer - slightly delayed - Admirals club was excellent quality food, drink made up for flight seating. No food offerred on flight, you ahd to prebook.

We experience delays on departure and connecting flights resulting in 14 hour to our next departure. We were accommodated with a night's stay but was only provided a 12 dollar meals accommodation. The airlines rules state.at least 50 dollars. In any case, it can not make up for the whole day missed on our vacation in Sydney Australia.

I can say I will not be taking this airline again any time soon. Seat were uncomfortable and too tight. Lack of chair screen and little overhead space.

Plane felt so crowded and tightly packed. The chair itself was not comfortable.

They attended to my needs as I couldn't walk and they provided a wheelchair for me.q

Poor availability of food. Cold cabin temperature. Extremely long waiting time for a flight attendant to respond to a call button signal.

I purchased a carry on bag online…was supposed to cost $72 but after a whole slew of bs charges, the total was over $175.00. Because of these hidden charges, I will not even consider flying Frontier ever again. It’s just not worth the hassle. I’m scratching this company off my list forever.

Flight was OK. Seats were good no cell phone charges on the plane no TVs or entertainment.

There were 3 leg for the trip and each leg was delayed by 90 minutes or more. The boarding process takes forever with people waiting on the jetway even though most folks do not have carry-on. The whole process is poorly managed.

Flight cancelled and was told by a rude gate agent that they don’t accommodate on other airlines. Had to wait 5 hours for a connecting flight that had a 7 hour layover. Would not allow bags to be checked early so we couldn’t go through security .Had to rent a car for the afternoon to store bags and get a meal. Also incurred a hotel fee. No apology or reason given for the cancellation- just rudeness.

They cancelled the flight then did nothing to help us rebook. It was awful - I won’t fly with them again

The process of buying the ticket and navigating all the hidden charges that Frontier throws at you was a terrible experience. The actual airport experience and flying was fine.

The truck that was refueling the plane drove away with the hose still connected to the plane and ripped part of the plane off with it

Not have to pay for every single item to take a flight. Seating and delays sucked.

The boarding time. I was in Section 1 the lady in charge just let people in section 3 without see us. Make a line , I have to step out and ask her. We were in the line and she just take my ticket and that’s it, so if I don’t ask her she could leave us at the end! We paid more for that privilege and. She doesn’t care….

See my previous comment which is mostly about our flight from Phoenix to SFO

Book cheap flights from St. Louis to Ontario

Recent one-way flight deals

 
Only flying one-way? Below are some of the best one-way flight deals from St. Louis to Ontario found on KAYAK in the last 72 hours.
5/8Mi
1 stopFrontier
5h 55mSTL-ONT
$45
5/1Mi
1 stopFrontier
5h 55mSTL-ONT
$46
5/30Do
1 stopDelta
6h 53mSTL-ONT
$172
5/27Mo
2 stopsAmerican Airlines
8h 26mSTL-ONT
$214
5/9Do
2 stopsAmerican Airlines
9h 39mSTL-ONT
$222
6/29Sa
1 stopDelta
7h 35mSTL-ONT
$253
5/28Di
2 stopsUnited Airlines
21h 14mSTL-ONT
$254
6/8Sa
2 stopsUnited Airlines
15h 22mSTL-ONT
$269
6/10Mo
2 stopsAlaska Airlines
16h 55mSTL-ONT
$272
4/30Di
2 stopsAlaska Airlines
12h 02mSTL-ONT
$409

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Last minute flights from St. Louis to Ontario

Last minute flight, train and bus deals

 
These last-minute flight deals are the cheapest flights found on KAYAK in the last 72 hours for flights from St. Louis to Ontario that are departing in the next 10 days.
4/30Di
multi-stopFrontier
9h 09mSTL-ONT
5/1Mi
multi-stopFrontier
9h 29mONT-STL
$120
4/29Mo
multi-stopFrontier
12h 22mSTL-ONT
5/4Sa
multi-stopFrontier
12h 17mONT-STL
$169
4/30Di
multi-stopFrontier
15h 36mSTL-ONT
5/3Fr
multi-stopFrontier
6h 52mONT-STL
$188
4/30Di
multi-stopFrontier
9h 09mSTL-ONT
5/1Mi
multi-stopFrontier
9h 29mONT-STL
$189
4/29Mo
multi-stopFrontier
12h 22mSTL-ONT
4/30Di
multi-stopFrontier
6h 48mONT-STL
$190
4/30Di
multi-stopUnited Airlines
12h 30mSTL-ONT
5/1Mi
multi-stopUnited Airlines
9h 23mONT-STL
$631
4/30Di
multi-stopUnited Airlines
12h 30mSTL-ONT
5/1Mi
multi-stopUnited Airlines
9h 23mONT-STL
$719
4/30Di
multi-stopAlaska Airlines
8h 53mSTL-ONT
5/4Sa
multi-stopAlaska Airlines
10h 39mONT-STL
$770
4/30Di
multi-stopUnited Airlines
12h 30mSTL-ONT
5/1Mi
multi-stopUnited Airlines
8h 31mONT-STL
$784
4/30Di
multi-stopAlaska Airlines
8h 53mSTL-ONT
5/4Sa
multi-stopAlaska Airlines
10h 39mONT-STL
$895

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St. Louis - Ontario Flights

Departure:

St. Louis (STL)United States

Destination:

Ontario (ONT)United States

Return flight deals:

Ontario - St. Louis

Cabin classes:

$125