$81+ Cheap flights from St. Louis to Ontario (STL - ONT)
This is the cheapest round-trip flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 10/10. Fares are subject to change and may not be available on all flights or dates of travel.
STL — ONT
Oct 11 — Oct 181
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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One-way
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 September 11, 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 September 11, 2026.
This Kiwi.com deal was found by Cheapflights users on 9/10. 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.
Fri 11/137:59 pm -
1 stop16h 43m
Wed 11/186:25 am -
1 stop6h 58m
Deal found 9/10![Frontier logo]()
$146
This Expedia deal was found by Cheapflights users on 9/8. 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.
Mon 10/58:10 pm -
1 stop16h 20m
Wed 10/711:45 am -
1 stop10h 14m
Deal found 9/8![Frontier logo]()
$165
This Booking.com deal was found by Cheapflights users on 9/9. 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.
Wed 11/44:18 pm -
1 stop9h 33m
Sat 11/711:52 am -
1 stop5h 22m
Deal found 9/9![Frontier logo]()
$169
This Booking.com deal was found by Cheapflights users on 9/9. 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 10/177:42 pm -
1 stop6h 08m
Sat 10/246:15 am -
1 stop10h 42m
Deal found 9/9![Frontier logo]()
$171
This Booking.com deal was found by Cheapflights users on 9/9. 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.
Fri 10/168:00 pm -
1 stop16h 29m
Sat 11/711:52 am -
1 stop5h 22m
Deal found 9/9![Frontier logo]()
$176
This Booking.com deal was found by Cheapflights users on 9/9. 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 10/38:10 pm -
1 stop5h 37m
Sat 10/3111:52 am -
1 stop5h 22m
Deal found 9/9![Frontier logo]()
$183
This Booking.com deal was found by Cheapflights users on 9/10. 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.
Wed 9/308:10 pm -
1 stop5h 37m
Wed 10/711:45 am -
1 stop10h 14m
Deal found 9/10![Frontier logo]()
$185
This Mytrip deal was found by Cheapflights users on 9/9. 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.
Fri 10/238:00 pm -
1 stop16h 29m
Tue 10/2711:52 am -
1 stop25h 31m
Deal found 9/9![Frontier logo]()
$191
This Kiwi.com deal was found by Cheapflights users on 9/10. 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.
Fri 11/137:59 pm -
1 stop16h 43m
Tue 11/175:07 pm -
2 stops20h 16m
Deal found 9/10![Frontier logo]()
$196
This Booking.com deal was found by Cheapflights users on 9/10. 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.
Fri 10/238:00 pm -
1 stop16h 29m
Mon 10/2611:52 am -
1 stop5h 23m
Deal found 9/10![Frontier logo]()
$205
This Kiwi.com deal was found by Cheapflights users on 9/10. 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.
Fri 10/28:10 pm -
1 stop16h 20m
Tue 10/611:45 am -
2 stops21h 47m
Deal found 9/10![Frontier logo]()
$219
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 September 11, 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 September 11, 2026.
This Delta deal was found by Cheapflights users on 9/10. 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.
Thu 11/122:31 pm -
1 stop9h 26m
Tue 11/176:00 am -
1 stop5h 30m
Deal found 9/10![Delta logo]()
$357
This Southwest deal was found by Cheapflights users on 9/7. 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.
Sat 10/241:50 pm -
2 stops8h 55m
Thu 10/294:15 pm -
1 stop7h 05m
Deal found 9/7![Southwest logo]()
$362
This American Airlines deal was found by Cheapflights users on 9/10. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/145:40 am -
2 stops8h 34m
Tue 10/201:05 pm -
2 stops8h 37m
Deal found 9/10![American Airlines logo]()
$450
This Booking.com deal was found by Cheapflights users on 9/10. 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.
Wed 10/287:02 am -
1 stop8h 14m
Tue 11/104:06 pm -
2 stops20h 19m
Deal found 9/10![Alaska Airlines logo]()
$456
This United Airlines deal was found by Cheapflights users on 9/9. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 12/811:05 am -
2 stops11h 15m
Tue 12/155:00 am -
1 stop5h 43m
Deal found 9/9![United Airlines logo]()
$462
This Delta deal was found by Cheapflights users on 9/7. 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.
Thu 12/102:33 pm -
1 stop9h 23m
Tue 12/151:11 pm -
1 stop6h 17m
Deal found 9/7![Delta logo]()
$357
This Delta deal was found by Cheapflights users on 9/9. 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 10/277:45 am -
1 stop6h 51m
Mon 11/26:00 am -
1 stop5h 32m
Deal found 9/9![Delta logo]()
$357
This United Airlines deal was found by Cheapflights users on 9/10. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 1/161:09 pm -
2 stops10h 31m
Sat 1/236:00 am -
1 stop8h 43m
Deal found 9/10![United Airlines logo]()
$462
This Delta deal was found by Cheapflights users on 9/9. 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 12/217:38 pm -
1 stop6h 21m
Wed 1/67:00 am -
2 stops12h 41m
Deal found 9/9![Delta logo]()
$385
This Southwest deal was found by Cheapflights users on 9/8. 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.
Sat 10/108:55 am -
2 stops9h 05m
Fri 10/165:20 am -
2 stops7h 25m
Deal found 9/8![Southwest logo]()
$470
This Alaska Airlines deal was found by Cheapflights users on 9/8. 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 9/246:29 am -
1 stop9h 47m
Tue 9/296:02 am -
1 stop10h 36m
Deal found 9/8![Alaska Airlines logo]()
$509
Last-minute flights from St. Louis to OntarioDiscover last-minute flight deals from St. Louis to Ontario. Data last updated September 11, 2026 and is based on user searches.
Discover last-minute flight deals from St. Louis to Ontario. Data last updated September 11, 2026 and is based on user searches.
This Booking.com deal was found by Cheapflights users on 9/10. 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.
Wed 9/308:10 pm -
1 stop5h 37m
Wed 10/711:45 am -
1 stop10h 14m
Deal found 9/10![Frontier logo]()
$185
This Kiwi.com deal was found by Cheapflights users on 9/10. 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.
Fri 10/28:10 pm -
1 stop16h 20m
Tue 10/611:45 am -
2 stops21h 47m
Deal found 9/10![Frontier logo]()
$219
This Booking.com deal was found by Cheapflights users on 9/9. 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 10/38:10 pm -
1 stop5h 37m
Sat 10/3111:52 am -
1 stop5h 22m
Deal found 9/9![Frontier logo]()
$183
This Booking.com deal was found by Cheapflights users on 9/9. 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 10/38:10 pm -
1 stop5h 37m
Tue 10/65:44 pm -
1 stop15h 48m
Deal found 9/9![Frontier logo]()
$243
This Expedia deal was found by Cheapflights users on 9/8. 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.
Mon 10/58:10 pm -
1 stop16h 20m
Wed 10/711:45 am -
1 stop10h 14m
Deal found 9/8![Frontier logo]()
$165
This Booking.com deal was found by Cheapflights users on 9/8. 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 10/107:42 pm -
1 stop6h 08m
Sat 10/176:15 am -
1 stop10h 42m
Deal found 9/8![Frontier logo]()
$236
This Booking.com deal was found by Cheapflights users on 9/9. 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.
Fri 10/168:00 pm -
1 stop16h 29m
Sat 11/711:52 am -
1 stop5h 22m
Deal found 9/9![Frontier logo]()
$176
This Booking.com deal was found by Cheapflights users on 9/9. 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 10/177:42 pm -
1 stop6h 08m
Sat 10/246:15 am -
1 stop10h 42m
Deal found 9/9![Frontier logo]()
$171
This Mytrip deal was found by Cheapflights users on 9/9. 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.
Fri 10/238:00 pm -
1 stop16h 29m
Tue 10/2711:52 am -
1 stop25h 31m
Deal found 9/9![Frontier logo]()
$191
This Booking.com deal was found by Cheapflights users on 9/10. 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.
Fri 10/238:00 pm -
1 stop16h 29m
Mon 10/2611:52 am -
1 stop5h 23m
Deal found 9/10![Frontier logo]()
$205
This Booking.com deal was found by Cheapflights users on 9/8. 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 10/247:42 pm -
1 stop6h 08m
Mon 10/2611:52 am -
1 stop5h 23m
Deal found 9/8![Frontier logo]()
$222
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 September 11, 2026.
Search for one-way flight options from St. Louis to Ontario. Find affordable one-way fares based on user searches. Data last updated September 11, 2026.
This Super.com deal was found by Cheapflights users on 9/8. 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 10/107:42 pm -
1 stop6h 08m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/8![Frontier logo]()
$81
This Super.com deal was found by Cheapflights users on 9/10. 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 9/308:10 pm -
1 stop5h 37m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/10![Frontier logo]()
$86
This Super.com deal was found by Cheapflights users on 9/9. 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 11/77:59 pm -
1 stop5h 52m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/9![Frontier logo]()
$90
This Super.com deal was found by Cheapflights users on 9/8. 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.
Fri 10/238:00 pm -
1 stop16h 29m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/8![Frontier logo]()
$93
This Super.com deal was found by Cheapflights users on 9/8. 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.
Fri 10/28:10 pm -
1 stop16h 20m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/8![Frontier logo]()
$94
This Super.com deal was found by Cheapflights users on 9/9. 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.
Fri 11/67:59 pm -
1 stop16h 43m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/9![Frontier logo]()
$104
This Frontier deal was found by Cheapflights users on 9/9. 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 12/127:49 pm -
1 stop6h 31m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/9![Frontier logo]()
$136
This Frontier deal was found by Cheapflights users on 9/10. 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 10/72:29 pm -
2 stops11h 18m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/10![Frontier logo]()
$141
This Super.com deal was found by Cheapflights users on 9/9. 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 10/612:17 pm -
1 stop6h 42m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/9![Frontier logo]()
$144
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 September 11, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $146 (Kiwi.com) |
One-way from | $81 (Super.com) |
Popular in | June |
Cheapest in | November |
Average price | $384 |
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 7,457,451 searches. Data last updated September 11, 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 Lambert-St Louis - ONT Ontario
STLONT
Lambert-St Louis
Thu 12/17
3:52 pm-6:15 am
1 stop16h 23m
Ontario
Wed 12/31
12:00 am-2:00 am
Nonstop0h 00m
$172
St. LouisOntario
STL Lambert-St Louis - ONT Ontario
STLONT
Lambert-St Louis
Wed 12/16
2:59 pm-6:15 am
2 stops17h 16m
Ontario
Wed 12/31
12:00 am-2:00 am
Nonstop0h 00m
$173
St. LouisOntario
STL Lambert-St Louis - ONT Ontario
STLONT
Lambert-St Louis
Mon 12/21
7:38 pm-11:59 pm
1 stop6h 21m
Ontario
Wed 12/31
12:00 am-2:00 am
Nonstop0h 00m
$179
St. LouisOntario
STL Lambert-St Louis - ONT Ontario
STLONT
Lambert-St Louis
Wed 9/23
12:17 pm-4:59 pm
1 stop6h 42m
Ontario
Wed 12/31
12:00 am-2:00 am
Nonstop0h 00m
$187
Quickest round-trip
St. LouisOntario
STL Lambert-St Louis - ONT Ontario
STLONT
Lambert-St Louis
Sat 9/26
8:10 pm-11:47 pm
1 stop5h 37m
Ontario
Wed 12/31
12:00 am-2:00 am
Nonstop0h 00m
$190
St. LouisOntario
STL Lambert-St Louis - ONT Ontario
STLONT
Lambert-St Louis
Sat 10/10
7:42 pm-11:16 am
2 stops17h 34m
Ontario
Wed 12/31
12:00 am-2:00 am
Nonstop0h 00m
$193
St. LouisOntario
STL Lambert-St Louis - ONT Ontario
STLONT
Lambert-St Louis
Thu 9/17
10:20 am-6:39 pm
1 stop10h 19m
Ontario
Wed 12/31
12:00 am-2:00 am
Nonstop0h 00m
$216
St. LouisOntario
STL Lambert-St Louis - ONT Ontario
STLONT
Lambert-St Louis
Fri 11/27
6:00 am-11:08 am
1 stop7h 08m
Ontario
Wed 12/31
12:00 am-2:00 am
Nonstop0h 00m
$231
St. LouisOntario
STL Lambert-St Louis - ONT Ontario
STLONT
Lambert-St Louis
Tue 10/6
5:36 pm-10:49 pm
1 stop7h 13m
Ontario
Wed 12/31
12:00 am-2:00 am
Nonstop0h 00m
$239
St. LouisOntario
STL Lambert-St Louis - ONT Ontario
STLONT
Lambert-St Louis
Wed 11/25
7:00 pm-11:49 pm
1 stop6h 49m
Ontario
Wed 12/31
12:00 am-2:00 am
Nonstop0h 00m
$240
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 September.
| 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 $310 and $436 in November.The cheapest round-trip price found within the last 5 days was $146 on Frontier (Nov 13-Nov 18).
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 September 11, 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
Overall
8.0
Boarding
8.1
Crew
8.6
Reviews
1 / 20
10.0
ExcellentWalter,May 2026
LAS - BUR
Entertainment
7.5
Food
7.0
Comfort
8.0
Overall
8.0
Boarding
8.1
Crew
8.6
Reviews
1 / 20
10.0
ExcellentWalter,May 2026
LAS - BUR
Entertainment
7.5
Food
7.0
Comfort
8.0
Overall
8.0
Boarding
8.1
Crew
8.6
Reviews
1 / 20
10.0
ExcellentWalter,May 2026
LAS - BUR
Entertainment
7.5
Food
7.0
Comfort
8.0
Overall
8.0
Boarding
8.1
Crew
8.6
Reviews
1 / 20
10.0
ExcellentWalter,May 2026
LAS - BUR
Entertainment
7.5
Food
7.0
Comfort
8.0
Overall
8.0
Boarding
8.1
Crew
8.6
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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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 7,457,451 searches. Data last updated September 11, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$143 | Average$289 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$292 | Average$385 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$292 | Average$448 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$292 | Average$520 | FlexibilityNo cancel fee | On-time69% |