$122+ Cheap flights from St. Louis to Ontario (STL - ONT)
This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 8/17. Fares are subject to change and may not be available on all flights or dates of travel.
STL — ONT
Aug 24 — Aug 311
Round-trip
1 adult, Economy
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Find cheap flights from St. Louis to Ontario with Cheapflights
1. Tell us where you want to go
Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”2. Select your favorite providers
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Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.Cheap flight deals from St. Louis to Ontario
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Cheapest flights from St. Louis to OntarioExplore the most affordable flight options available from St. Louis to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on July 25, 2026.
Explore the most affordable flight options available from St. Louis to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on July 25, 2026.
This Kiwi.com deal was found by Cheapflights users on 7/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/317:58 pm
STL
- ONT
1 stop16h 06m
Frontier
Sun 9/66:00 am
ONT
- STL
1 stop11h 13m
Frontier
Deal found 7/24![Frontier logo]()
$182
This Kiwi.com deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/118:08 pm
STL
- ONT
1 stop15h 56m
Frontier
Thu 8/1310:49 am
ONT
- STL
1 stop6h 34m
Frontier
Deal found 7/22![Frontier logo]()
$191
This Kiwi.com deal was found by Cheapflights users on 7/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/138:10 pm
STL
- ONT
1 stop29h 45m
Frontier
Wed 10/216:00 am
ONT
- STL
1 stop11h 15m
Frontier
Deal found 7/23![Frontier logo]()
$201
This Kiwi.com deal was found by Cheapflights users on 7/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/148:10 pm
STL
- ONT
1 stop16h 33m
Frontier
Wed 10/216:00 am
ONT
- STL
1 stop11h 15m
Frontier
Deal found 7/23![Frontier logo]()
$204
This Kiwi.com deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/1610:35 am
STL
- ONT
2 stops30h 02m
Frontier
Wed 9/302:55 pm
ONT
- STL
1 stop26h 20m
Frontier
Deal found 7/22![Frontier logo]()
$223
This Kiwi.com deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/216:41 pm
STL
- ONT
1 stop14h 31m
Frontier
Mon 9/286:00 am
ONT
- STL
1 stop11h 15m
Frontier
Deal found 7/22![Frontier logo]()
$231
This Kiwi.com deal was found by Cheapflights users on 7/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/196:41 pm
STL
- ONT
1 stop14h 31m
Frontier
Wed 10/216:00 am
ONT
- STL
1 stop11h 15m
Frontier
Deal found 7/23![Frontier logo]()
$237
This Frontier deal was found by Cheapflights users on 7/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/158:10 pm
STL
- ONT
1 stop5h 45m
Frontier
Tue 10/202:58 pm
ONT
- STL
1 stop8h 19m
Frontier
Deal found 7/21![Frontier logo]()
$248
This Frontier deal was found by Cheapflights users on 7/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/226:45 pm
STL
- ONT
1 stop15h 18m
Frontier
Sat 8/297:56 pm
ONT
- STL
1 stop21h 17m
Frontier
Deal found 7/21![Frontier logo]()
$249
Best flights from St. Louis to OntarioDiscover carefully curated flight deals from St. Louis to Ontario that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated July 25, 2026.
Discover carefully curated flight deals from St. Louis to Ontario that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated July 25, 2026.
This Expedia deal was found by Cheapflights users on 7/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/225:19 pm
STL
- ONT
1 stop24h 51m
Frontier
Mon 10/262:58 pm
ONT
- STL
1 stop8h 19m
Frontier
Deal found 7/19![Frontier logo]()
$264
This Alaska Airlines deal was found by Cheapflights users on 7/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/33:24 pm
STL
- ONT
1 stop9h 15m
Alaska Airlines
Sat 12/512:00 pm
ONT
- STL
1 stop9h 59m
Alaska Airlines
Deal found 7/24![Alaska Airlines logo]()
$367
This Delta deal was found by Cheapflights users on 7/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 11/237:55 pm
STL
- ONT
1 stop5h 53m
Delta
Thu 11/266:00 am
ONT
- STL
1 stop5h 23m
Delta
Deal found 7/19![Delta logo]()
$367
This Southwest deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/242:20 pm
STL
- ONT
2 stops8h 20m
Southwest
Mon 9/285:15 am
ONT
- STL
2 stops10h 05m
Southwest
Deal found 7/22![Southwest logo]()
$377
This Gotogate deal was found by Cheapflights users on 7/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/36:45 pm
STL
- ONT
1 stop23h 37m
Multiple Airlines
Tue 9/84:50 pm
ONT
- STL
2 stops19h 31m
Multiple Airlines
Deal found 7/19![Multiple Airlines logo]()
$423
This Frontier deal was found by Cheapflights users on 7/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/217:58 pm
STL
- ONT
1 stop5h 52m
Frontier
Mon 8/2410:49 am
ONT
- STL
1 stop6h 24m
Frontier
Deal found 7/19![Frontier logo]()
$291
This Delta deal was found by Cheapflights users on 7/20. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/3111:10 am
STL
- ONT
2 stops13h 33m
Delta
Wed 11/46:20 am
ONT
- STL
2 stops12h 39m
Delta
Deal found 7/20![Delta logo]()
$384
This Southwest deal was found by Cheapflights users on 7/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/1511:55 am
STL
- ONT
2 stops7h 55m
Southwest
Thu 9/175:15 am
ONT
- STL
2 stops10h 05m
Southwest
Deal found 7/21![Southwest logo]()
$423
This Delta deal was found by Cheapflights users on 7/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 11/177:30 am
STL
- ONT
1 stop7h 00m
Delta
Thu 11/266:00 am
ONT
- STL
1 stop5h 23m
Delta
Deal found 7/21![Delta logo]()
$395
This Delta deal was found by Cheapflights users on 7/20. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 11/177:55 pm
STL
- ONT
1 stop5h 53m
Delta
Tue 12/15:05 pm
ONT
- STL
1 stop5h 31m
Delta
Deal found 7/20![Delta logo]()
$403
This Delta deal was found by Cheapflights users on 7/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/177:55 am
STL
- ONT
1 stop6h 27m
Delta
Sat 10/245:52 pm
ONT
- STL
2 stops13h 11m
Delta
Deal found 7/23![Delta logo]()
$410
Last-minute flights from St. Louis to OntarioDiscover last-minute flight deals from St. Louis to Ontario. Data last updated July 25, 2026 and is based on user searches.
Discover last-minute flight deals from St. Louis to Ontario. Data last updated July 25, 2026 and is based on user searches.
This Kiwi.com deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/118:08 pm
STL
- ONT
1 stop15h 56m
Frontier
Thu 8/1310:49 am
ONT
- STL
1 stop6h 34m
Frontier
Deal found 7/22![Frontier logo]()
$191
This Frontier deal was found by Cheapflights users on 7/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/118:08 pm
STL
- ONT
1 stop5h 42m
Frontier
Wed 8/126:00 am
ONT
- STL
1 stop11h 23m
Frontier
Deal found 7/21![Frontier logo]()
$248
This Booking.com deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/158:08 pm
STL
- ONT
1 stop5h 42m
Frontier
Mon 8/1711:47 am
ONT
- STL
1 stop28h 03m
Frontier
Deal found 7/22![Frontier logo]()
$256
This Frontier deal was found by Cheapflights users on 7/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/226:45 pm
STL
- ONT
1 stop15h 18m
Frontier
Sat 8/297:56 pm
ONT
- STL
1 stop21h 17m
Frontier
Deal found 7/21![Frontier logo]()
$249
This Booking.com deal was found by Cheapflights users on 7/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/296:45 pm
STL
- ONT
1 stop15h 18m
Frontier
Tue 9/13:40 pm
ONT
- STL
1 stop24h 10m
Frontier
Deal found 7/24![Frontier logo]()
$261
This Kiwi.com deal was found by Cheapflights users on 7/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/317:58 pm
STL
- ONT
1 stop16h 06m
Frontier
Sun 9/66:00 am
ONT
- STL
1 stop11h 13m
Frontier
Deal found 7/24![Frontier logo]()
$182
This Booking.com deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/317:58 pm
STL
- ONT
1 stop5h 52m
Frontier
Thu 9/38:17 am
ONT
- STL
1 stop6h 14m
Frontier
Deal found 7/22![Frontier logo]()
$250
This Mytrip deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/317:58 pm
STL
- ONT
1 stop5h 52m
Frontier
Tue 9/83:40 pm
ONT
- STL
1 stop18h 11m
Frontier
Deal found 7/22![Frontier logo]()
$271
One-way flights from St. Louis to OntarioSearch for one-way flight options from St. Louis to Ontario. Find affordable one-way fares based on user searches. Data last updated July 25, 2026.
Search for one-way flight options from St. Louis to Ontario. Find affordable one-way fares based on user searches. Data last updated July 25, 2026.
This Super.com deal was found by Cheapflights users on 7/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/178:08 pm
STL
- ONT
1 stop5h 42m
Frontier
Deal found 7/23![Frontier logo]()
$122
This Super.com deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/247:58 pm
STL
- ONT
1 stop5h 52m
Frontier
Deal found 7/22![Frontier logo]()
$124
This iWofly deal was found by Cheapflights users on 7/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure iWofly is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/225:19 pm
STL
- ONT
1 stop28h 40m
Frontier
Deal found 7/23![Frontier logo]()
$128
This Super.com deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/196:45 pm
STL
- ONT
1 stop15h 18m
Frontier
Deal found 7/22![Frontier logo]()
$129
This Frontier deal was found by Cheapflights users on 7/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/2312:46 pm
STL
- ONT
1 stop10h 08m
Frontier
Deal found 7/21![Frontier logo]()
$130
This Frontier deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/178:10 pm
STL
- ONT
1 stop5h 45m
Frontier
Deal found 7/22![Frontier logo]()
$132
This Super.com deal was found by Cheapflights users on 7/20. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/226:45 pm
STL
- ONT
1 stop15h 18m
Frontier
Deal found 7/20![Frontier logo]()
$134
This Super.com deal was found by Cheapflights users on 7/20. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/16:45 pm
STL
- ONT
1 stop23h 09m
Frontier
Deal found 7/20![Frontier logo]()
$137
This Super.com deal was found by Cheapflights users on 7/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 8/307:58 pm
STL
- ONT
1 stop5h 52m
Frontier
Deal found 7/21![Frontier logo]()
$156
Find flight deals from St. Louis to Ontario
Discover tips and strategies to find the most affordable flight options for your journey from St. Louis (STL) to Ontario (ONT). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated July 25, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $182 (Kiwi.com) |
One-way from | $122 (Super.com) |
Popular in | June |
Cheapest in | November |
Average price | $404 |
Cheapflights Fare Finder
Customize your flight search to find flights from St. Louis to Ontario that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated July 25, 2026.
Use the filters below to find and compare flights from St. Louis to Ontario that are best for you.
Fly from
Fly to
Route
Depart
Return
Cheapest round-trip
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Thu 10/22
5:19 pm-4:10 pm
1 stop24h 51m
Ontario
Mon 10/26
2:58 pm-1:17 am
1 stop8h 19m
$264
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Fri 8/21
7:58 pm-11:50 pm
1 stop5h 52m
Ontario
Mon 8/24
10:49 am-7:13 pm
1 stop6h 24m
$291
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Thu 12/3
3:24 pm-10:39 pm
1 stop9h 15m
Ontario
Sat 12/5
12:00 pm-11:59 pm
1 stop9h 59m
$367
Quickest round-trip
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Mon 11/23
7:55 pm-11:48 pm
1 stop5h 53m
Ontario
Thu 11/26
6:00 am-1:23 pm
1 stop5h 23m
$367
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Thu 9/24
2:20 pm-8:40 pm
2 stops8h 20m
Ontario
Mon 9/28
5:15 am-5:20 pm
2 stops10h 05m
$377
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Sat 10/31
11:10 am-10:43 pm
2 stops13h 33m
Ontario
Wed 11/4
6:20 am-8:59 pm
2 stops12h 39m
$384
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Tue 11/17
7:30 am-12:30 pm
1 stop7h 00m
Ontario
Thu 11/26
6:00 am-1:23 pm
1 stop5h 23m
$395
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Tue 11/17
7:55 pm-11:48 pm
1 stop5h 53m
Ontario
Tue 12/1
5:05 pm-12:36 am
1 stop5h 31m
$403
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Sat 10/17
7:55 am-12:22 pm
1 stop6h 27m
Ontario
Sat 10/24
5:52 pm-9:03 am
2 stops13h 11m
$410
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Thu 9/3
6:45 pm-4:22 pm
1 stop23h 37m
Ontario
Tue 9/8
4:50 pm-2:21 pm
2 stops19h 31m
$423
Showing 1-10 of 22 resultsSorted by cheapest first
Compare providers for flights from St. Louis to Ontario
Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.
Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from St. Louis to Ontario in July.
| Provider | Price Accuracy | Trust Score* |
|---|---|---|
| Price Accuracy1 star | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy- | Trust Score*1 star | |
| Price Accuracy- | Trust Score*1 star | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy1 star | Trust Score*3 stars | |
| Price Accuracy1 star | Trust Score*3 stars |
- Most accurate provider: When it comes to deals on St. Louis-Ontario flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on St. Louis-Ontario flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from St. Louis-Ontario flight searches over the past month and is updated monthly.
- Most trusted provider: When it comes to deals on St. Louis-Ontario flights, Cheapflights users trust FlightHub the most. FlightHub has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for St. Louis-Ontario flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.
Best time to book a flight from St. Louis to Ontario
Have a flexible travel schedule? Discover the best time to fly to Ontario from St. Louis with our price prediction graph.
STL-ONT
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.
Cheapflights Insights
Everything you need to know about your flight from St. Louis to Ontario
Prices
More
What is the cheapest month to book a flight from St. Louis to Ontario?
Currently, November is the cheapest month in which you can book a flight from St. Louis to Ontario (average of $292). Flying from St. Louis to Ontario in June is currently the most expensive (average of $526). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.
How much does it cost to fly round-trip from St. Louis to Ontario?
Airfare is below average for this route at the moment.
St. Louis to Ontario flights typically cost between $301 and $410 in August.The cheapest round-trip price found within the last 5 days was $182 on Frontier (Aug 31-Sep 6).
What’s the top layover airport for flights from St. Louis to Ontario?
Share of 1-stop round-trip flights from St. Louis to Ontario chosen by Cheapflights users in the past 12 months, using the same layover each way.
Denver (DEN) – chosen by Cheapflights users on 63% of 1-stop itineraries from St. Louis to Ontario on Cheapflights.
What’s the cheapest layover airport for flights from St. Louis to Ontario?
Average round-trip fare for 1-stop flights from St. Louis to Ontario, chosen by Cheapflights users in the past 12 months, with the same layover each way.
Denver (DEN) is the most affordable 1-stop option, with an average round-trip price of $272.
What’s the fastest layover option from St. Louis to Ontario?
Shortest average travel time for 1-stop one-way flights from St. Louis to Ontario, based on itineraries clicked by Cheapflights users over the past 12 months, grouped by layover airport.
Flights via Phoenix (PHX) have the shortest average one-way travel time for 1-stop routes: 5h 53m.
Which airport typically offers the quickest layover for flights from St. Louis to Ontario?
Average layover duration for 1-stop one-way flights from St. Louis to Ontario, chosen by Cheapflights users in the last 12 months, grouped by stopover airport.
Flights via Sacramento (SMF) offer the fastest connection on this route, with an average layover time of 0h 53m.
Reviews of airlines servicing Ontario
Get insights into the airlines that provide service to Ontario. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Ontario. Reviews last updated July 25, 2026.
Peruse reviews from past customers who have flown with Southwest,United Airlines, andAmerican Airlines from St. Louis to Ontario to help guide your decision. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Entertainment
7.5
Food
7.0
Comfort
8.0
Crew
8.6
Boarding
8.1
Overall
8.0
Reviews
1 / 20
10.0
ExcellentWalter,May 2026
LAS - BUR
Entertainment
7.5
Food
7.0
Comfort
8.0
Crew
8.6
Boarding
8.1
Overall
8.0
Reviews
1 / 20
10.0
ExcellentWalter,May 2026
LAS - BUR
Entertainment
7.5
Food
7.0
Comfort
8.0
Crew
8.6
Boarding
8.1
Overall
8.0
Reviews
1 / 20
10.0
ExcellentWalter,May 2026
LAS - BUR
Entertainment
7.5
Food
7.0
Comfort
8.0
Crew
8.6
Boarding
8.1
Overall
8.0
Reviews
1 / 20
10.0
ExcellentWalter,May 2026
LAS - BUR
Entertainment
7.5
Food
7.0
Comfort
8.0
Crew
8.6
Boarding
8.1
Overall
8.0
Reviews
1 / 20
10.0
ExcellentWalter,May 2026
LAS - BUR
Related info for your journey
Find useful and relevant information for your journey from St. Louis to Ontario. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.
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Other flights to Ontario
Explore flights to Ontario departing from other origins. Flights are based on user searches made on Cheapflights and were last updated on July 25, 2026.
St. Louis and Ontario flights
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Top 4 airlines flying from St. Louis to Ontario
Discover the top 4 airlines that operate flights from St. Louis to Ontario. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated July 25, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$143 | Average$288 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$201 | Average$520 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$284 | Average$346 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$292 | Average$437 | FlexibilityNo cancel fee | On-time63% |