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STL - ONT

$50 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 6/3. 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
Sun 6/2
Sun 6/9

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 43,693,958 times on KAYAK, and here is why:

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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
8:04 pm - 11:59 pmSTL-ONT
5h 55m1 stop
12:59 am - 9:29 amONT-STL
6h 30m1 stop
$119Frontier
Find Deal
Mon, Jun 3 - Tue, Jun 4
8:04 pm - 11:59 pmSTL-ONT
5h 55m1 stop
12:59 am - 9:36 amONT-STL
6h 37m1 stop
$120Frontier
Find Deal
Sat, May 25 - Thu, May 30
3:53 pm - 11:39 pmSTL-ONT
9h 46m1 stop
4:24 pm - 9:04 amONT-STL
14h 40m2 stops
Thu, Aug 1 - Tue, Aug 13
7:55 am - 12:13 pmSTL-ONT
6h 18m1 stop
5:20 pm - 12:46 amONT-STL
5h 26m1 stop
$354Delta
Find Deal
Wed, May 29 - Wed, May 29
2:29 pm - 10:38 pmSTL-ONT
10h 09m2 stops
5:00 pm - 12:39 amONT-STL
5h 39m1 stop
$358Delta
Find Deal
Wed, Jun 26 - Wed, Jul 10
2:21 pm - 10:40 pmSTL-ONT
10h 19m2 stops
12:49 am - 9:37 amONT-STL
6h 48m1 stop
Wed, Jun 26 - Tue, Jul 9
8:01 am - 3:48 pmSTL-ONT
9h 47m2 stops
6:40 am - 5:17 pmONT-STL
8h 37m2 stops
$550American Airlines
Find Deal
Thu, Aug 1 - Tue, Aug 13
5:21 am - 11:47 amSTL-ONT
8h 26m2 stops
10:29 pm - 9:53 amONT-STL
9h 24m1 stop
$583American Airlines
Find Deal
Thu, May 16 - Mon, May 20
1:37 pm - 8:53 pmSTL-ONT
9h 16m1 stop
5:15 am - 12:46 pmONT-STL
5h 31m1 stop
$593United Airlines
Find Deal
Tue, May 21 - Thu, May 23
5:31 pm - 10:27 pmSTL-ONT
30h 56m2 stops
6:25 pm - 2:16 pmONT-STL
17h 51m2 stops
$601United Airlines
Find Deal
Fri, May 31 - Fri, Jun 7

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 $50. Frontier proposed a round-trip connection from $119 and Delta from $354.

Good to know

Low season

August

High season

September

Cheapest flight

$50
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 $50 for a one-way ticket and $119 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?

    oneworld, Star Alliance, and SkyTeam 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 American Airlines?

    The two airlines most popular with KAYAK users for flights from St. Louis to Ontario are Delta and American Airlines. With an average price for the route of $407 and an overall rating of 8.0, Delta is the most popular choice. American Airlines is also a great choice for the route, with an average price of $496 and an overall rating of 7.3.

  • 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 10848 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.

Generally good but there wasn’t any staff available when my luggage didn’t appear at baggage claim in Fresno. It took about half an hour to locate a staff member to open up the locked room where it was being kept.

Do not like the feeling of being in the basic economy. Everyone should feel good no matter what.

Our original business class flight was cancelled so we not only downgraded but we were also spread out across the plane not sitting together in separate middle seats. My poor kids were scared and couldn’t see me on the flight and the crew wasn’t sensitive to the situation and what the airlines did to us. Very dissatisfied with United airlines.

The WiFi didn’t work and the seats are too close together. Very uncomfortable.

So so. Terrible aircraft choice for that leg of the flight.

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

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.

Six hour delay. Poor customer service. No voucher. Bad communication. Missed important appointments.

Our flight was delayed an hour, then when we got to board our flight finally, we were waiting in our seats for take off for 45 minutes before it was communicated that there was a maintenance issue therefore we waited on the plane for over an hour while that was resolved. We did not get to Phoenix until almost 3 hours after we were originally supposed to. This was the first and last time I will be flying Frontier.

Flight was canceled with little warning. Flight was rebooked through Ontario, California and connecting flight was delayed by over three hours. Frontier is living up to their Greyhound of the skies reputation for sure.

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

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

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

The check in at the airport was awful. Told I need to pay for a bag. The item was taken at screening. I went back to get my $ back and they gave me a coupon with a QR code that doesn’t work. Worst costumer service ever!!!!!

4 hour delay because they used our aircraft to fly a different segment (per the captain)

Lost baggage on my connecting flight. 24 hours later, still no update on my bags.

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.
6/3Mon
1 stopFrontier
5h 55mSTL-ONT
$50
6/7Fri
1 stopFrontier
5h 47mSTL-ONT
$55
5/30Thu
2 stopsAmerican Airlines
9h 39mSTL-ONT
$182
5/30Thu
1 stopAlaska Airlines
10h 26mSTL-ONT
$197
5/30Thu
2 stopsAlaska Airlines
13h 15mSTL-ONT
$258
5/27Mon
2 stopsAmerican Airlines
8h 26mSTL-ONT
$274
5/21Tue
2 stopsUnited Airlines
16h 17mSTL-ONT
$288
5/21Tue
1 stopDelta
6h 18mSTL-ONT
$290
5/17Fri
2 stopsUnited Airlines
21h 15mSTL-ONT
$304
5/9Thu
2 stopsDelta
12h 07mSTL-ONT
$356

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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.
5/8Wed
multi-stopFrontier
5h 55mSTL-ONT
5/21Tue
multi-stopFrontier
14h 32mONT-STL
$146
5/8Wed
multi-stopFrontier
5h 55mSTL-ONT
5/20Mon
multi-stopFrontier
10h 10mONT-STL
$162
5/8Wed
multi-stopFrontier
12h 22mSTL-ONT
5/21Tue
multi-stopFrontier
11h 44mONT-STL
$167
5/6Mon
multi-stop
12h 44mSTL-ONT
5/8Wed
multi-stop
9h 29mONT-STL
$519
5/6Mon
multi-stop
12h 44mSTL-ONT
5/7Tue
multi-stop
6h 48mONT-STL
$602
5/6Mon
multi-stopAmerican Airlines
9h 39mSTL-ONT
5/8Wed
multi-stopAmerican Airlines
8h 06mONT-STL
$752
5/7Tue
multi-stopUnited Airlines
6h 02mSTL-ONT
5/8Wed
multi-stopUnited Airlines
8h 31mONT-STL
$864
5/7Tue
multi-stopUnited Airlines
12h 43mSTL-ONT
5/8Wed
multi-stopUnited Airlines
5h 33mONT-STL
$913
5/5Sun
multi-stopDelta
6h 52mSTL-ONT
6/1Sat
multi-stopDelta
7h 57mONT-STL
$920
5/5Sun
multi-stopDelta
6h 52mSTL-ONT
5/18Sat
multi-stopDelta
7h 57mONT-STL
$1,008

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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