$127+ 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 7/20. Fares are subject to change and may not be available on all flights or dates of travel.
STL — ONT
Jul 7 — Jul 141
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 June 7, 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 June 7, 2026.
This Kiwi.com deal was found by Cheapflights users on 6/3. 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 7/213:41 pm
STL
- ONT
1 stop18h 56m
Frontier
Wed 7/296:00 am
ONT
- STL
1 stop11h 23m
Frontier
Deal found 6/3![Frontier logo]()
$191
This Kiwi.com deal was found by Cheapflights users on 6/2. 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 8/268:08 pm
STL
- ONT
1 stop15h 57m
Frontier
Mon 8/3110:50 am
ONT
- STL
1 stop6h 33m
Frontier
Deal found 6/2![Frontier logo]()
$243
This Kiwi.com deal was found by Cheapflights users on 6/2. 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 8/268:08 pm
STL
- ONT
1 stop15h 57m
Frontier
Sat 8/2910:50 am
ONT
- STL
1 stop6h 33m
Frontier
Deal found 6/2![Frontier logo]()
$245
This Kiwi.com deal was found by Cheapflights users on 6/3. 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 8/144:57 pm
STL
- ONT
2 stops32h 53m
Frontier
Wed 8/1910:50 am
ONT
- STL
1 stop6h 33m
Frontier
Deal found 6/3![Frontier logo]()
$246
This Kiwi.com deal was found by Cheapflights users on 6/4. 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 7/78:08 pm
STL
- ONT
1 stop15h 56m
Frontier
Tue 7/283:40 pm
ONT
- STL
1 stop24h 25m
Frontier
Deal found 6/4![Frontier logo]()
$247
This Kiwi.com deal was found by Cheapflights users on 6/4. 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 9/78:08 pm
STL
- ONT
1 stop29h 41m
Frontier
Mon 9/149:49 pm
ONT
- STL
1 stop12h 02m
Frontier
Deal found 6/4![Frontier logo]()
$253
This Kiwi.com deal was found by Cheapflights users on 6/2. 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 8/248:08 pm
STL
- ONT
1 stop15h 57m
Frontier
Mon 8/3110:50 am
ONT
- STL
1 stop6h 33m
Frontier
Deal found 6/2![Frontier logo]()
$261
This Kiwi.com deal was found by Cheapflights users on 6/2. 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 8/248:08 pm
STL
- ONT
1 stop15h 57m
Frontier
Sat 8/2910:50 am
ONT
- STL
1 stop6h 33m
Frontier
Deal found 6/2![Frontier logo]()
$263
This Frontier deal was found by Cheapflights users on 6/6. 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 9/18:08 pm
STL
- ONT
1 stop5h 41m
Frontier
Wed 9/26:00 am
ONT
- STL
1 stop11h 23m
Frontier
Deal found 6/6![Frontier logo]()
$264
This Booking.com deal was found by Cheapflights users on 6/5. 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.
Tue 7/147:03 pm
STL
- ONT
1 stop15h 00m
Frontier
Sat 7/186:00 am
ONT
- STL
1 stop11h 23m
Frontier
Deal found 6/5![Frontier logo]()
$266
This Frontier deal was found by Cheapflights users on 6/5. 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 9/1212:46 pm
STL
- ONT
1 stop10h 08m
Frontier
Wed 9/169:49 pm
ONT
- STL
1 stop12h 02m
Frontier
Deal found 6/5![Frontier logo]()
$283
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 June 7, 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 June 7, 2026.
This Frontier deal was found by Cheapflights users on 6/6. 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 9/18:08 pm
STL
- ONT
1 stop5h 41m
Frontier
Wed 9/26:00 am
ONT
- STL
1 stop11h 23m
Frontier
Deal found 6/6![Frontier logo]()
$264
This Delta deal was found by Cheapflights users on 6/2. 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.
Sun 8/308:00 am
STL
- ONT
1 stop6h 05m
Delta
Sun 8/305:05 pm
ONT
- STL
1 stop5h 36m
Delta
Deal found 6/2![Delta logo]()
$477
This United Airlines deal was found by Cheapflights users on 6/2. 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.
Wed 8/265:10 am
STL
- ONT
2 stops16h 51m
United Airlines
Wed 9/25:00 am
ONT
- STL
2 stops15h 00m
United Airlines
Deal found 6/2![United Airlines logo]()
$539
This Southwest deal was found by Cheapflights users on 6/6. 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.
Mon 7/63:35 pm
STL
- ONT
2 stops8h 40m
Southwest
Mon 7/136:30 am
ONT
- STL
2 stops8h 00m
Southwest
Deal found 6/6![Southwest logo]()
$558
This American Airlines deal was found by Cheapflights users on 6/7. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 6/225:29 am
STL
- ONT
1 stop8h 20m
American Airlines
Wed 7/11:11 pm
ONT
- STL
2 stops8h 48m
American Airlines
Deal found 6/7![American Airlines logo]()
$572
This CheapOair deal was found by Cheapflights users on 6/6. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 6/282:56 pm
STL
- ONT
1 stop26h 12m
Frontier
Sun 7/53:40 pm
ONT
- STL
1 stop24h 35m
Frontier
Deal found 6/6![Frontier logo]()
$360
This Booking.com deal was found by Cheapflights users on 6/6. 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.
Tue 6/238:08 pm
STL
- ONT
1 stop5h 41m
Frontier
Wed 6/243:34 pm
ONT
- STL
1 stop20h 32m
Frontier
Deal found 6/6![Frontier logo]()
$362
This Frontier deal was found by Cheapflights users on 6/2. 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 7/32:56 pm
STL
- ONT
1 stop6h 55m
Frontier
Mon 7/610:49 am
ONT
- STL
1 stop6h 34m
Frontier
Deal found 6/2![Frontier logo]()
$392
This United Airlines deal was found by Cheapflights users on 6/2. 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.
Wed 8/265:10 am
STL
- ONT
2 stops16h 51m
United Airlines
Tue 9/15:00 am
ONT
- STL
2 stops15h 00m
United Airlines
Deal found 6/2![United Airlines logo]()
$539
This United Airlines deal was found by Cheapflights users on 6/5. 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 9/18:00 am
STL
- ONT
2 stops14h 01m
United Airlines
Wed 9/26:00 am
ONT
- STL
2 stops8h 34m
United Airlines
Deal found 6/5![United Airlines logo]()
$554
This United Airlines deal was found by Cheapflights users on 6/3. 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 8/111:36 pm
STL
- ONT
2 stops8h 25m
United Airlines
Wed 8/125:00 am
ONT
- STL
1 stop5h 40m
United Airlines
Deal found 6/3![United Airlines logo]()
$556
Last-minute flights from St. Louis to OntarioDiscover last-minute flight deals from St. Louis to Ontario. Data last updated June 7, 2026 and is based on user searches.
Discover last-minute flight deals from St. Louis to Ontario. Data last updated June 7, 2026 and is based on user searches.
This Frontier deal was found by Cheapflights users on 6/6. 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.
Mon 6/292:56 pm
STL
- ONT
1 stop6h 55m
Frontier
Sat 7/116:00 am
ONT
- STL
1 stop11h 23m
Frontier
Deal found 6/6![Frontier logo]()
$306
This Gotogate deal was found by Cheapflights users on 6/3. 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.
Tue 6/307:46 pm
STL
- ONT
1 stop21h 22m
Frontier
Tue 7/71:38 pm
ONT
- STL
1 stop26h 27m
Frontier
Deal found 6/3![Frontier logo]()
$292
This CheapOair deal was found by Cheapflights users on 6/6. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 7/67:10 pm
STL
- ONT
1 stop22h 04m
Frontier
Tue 7/143:40 pm
ONT
- STL
1 stop24h 25m
Frontier
Deal found 6/6![Frontier logo]()
$301
This Kiwi.com deal was found by Cheapflights users on 6/4. 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 7/78:08 pm
STL
- ONT
1 stop15h 56m
Frontier
Tue 7/283:40 pm
ONT
- STL
1 stop24h 25m
Frontier
Deal found 6/4![Frontier logo]()
$247
This Booking.com deal was found by Cheapflights users on 6/3. 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.
Tue 7/77:03 pm
STL
- ONT
1 stop15h 00m
Frontier
Tue 7/143:40 pm
ONT
- STL
1 stop24h 25m
Frontier
Deal found 6/3![Frontier logo]()
$294
This Frontier deal was found by Cheapflights users on 6/6. 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.
Mon 7/138:08 pm
STL
- ONT
1 stop5h 42m
Frontier
Sat 7/186:00 am
ONT
- STL
1 stop11h 23m
Frontier
Deal found 6/6![Frontier logo]()
$291
This Booking.com deal was found by Cheapflights users on 6/5. 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.
Tue 7/147:03 pm
STL
- ONT
1 stop15h 00m
Frontier
Sat 7/186:00 am
ONT
- STL
1 stop11h 23m
Frontier
Deal found 6/5![Frontier logo]()
$266
This Booking.com deal was found by Cheapflights users on 6/6. 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.
Tue 7/147:03 pm
STL
- ONT
1 stop15h 00m
Frontier
Fri 7/176:00 am
ONT
- STL
1 stop11h 23m
Frontier
Deal found 6/6![Frontier logo]()
$293
This Kiwi.com deal was found by Cheapflights users on 6/3. 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 7/213:41 pm
STL
- ONT
1 stop18h 56m
Frontier
Wed 7/296:00 am
ONT
- STL
1 stop11h 23m
Frontier
Deal found 6/3![Frontier logo]()
$191
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 June 7, 2026.
Search for one-way flight options from St. Louis to Ontario. Find affordable one-way fares based on user searches. Data last updated June 7, 2026.
This Trip.com deal was found by Cheapflights users on 6/5. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 7/207:10 pm
STL
- ONT
1 stop22h 04m
Frontier
Deal found 6/5![Frontier logo]()
$127
This Trip.com deal was found by Cheapflights users on 6/6. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 7/317:10 pm
STL
- ONT
1 stop14h 53m
Frontier
Deal found 6/6![Frontier logo]()
$135
This Super.com deal was found by Cheapflights users on 6/5. 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 7/118:08 pm
STL
- ONT
1 stop15h 56m
Frontier
Deal found 6/5![Frontier logo]()
$136
This CheapOair deal was found by Cheapflights users on 6/5. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 11/35:32 pm
STL
- ONT
1 stop24h 38m
Frontier
Deal found 6/5![Frontier logo]()
$143
This Super.com deal was found by Cheapflights users on 6/5. 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 8/128:08 pm
STL
- ONT
1 stop5h 42m
Frontier
Deal found 6/5![Frontier logo]()
$149
This Super.com deal was found by Cheapflights users on 6/4. 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 6/307:46 pm
STL
- ONT
1 stop21h 22m
Frontier
Deal found 6/4![Frontier logo]()
$150
This Super.com deal was found by Cheapflights users on 6/3. 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 8/108:08 pm
STL
- ONT
1 stop5h 42m
Frontier
Deal found 6/3![Frontier logo]()
$153
This Super.com deal was found by Cheapflights users on 6/3. 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.
Thu 8/68:08 pm
STL
- ONT
1 stop5h 42m
Frontier
Deal found 6/3![Frontier logo]()
$154
This Super.com deal was found by Cheapflights users on 6/4. 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 7/188:08 pm
STL
- ONT
1 stop5h 42m
Frontier
Deal found 6/4![Frontier logo]()
$156
This Super.com deal was found by Cheapflights users on 6/4. 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 7/47:38 pm
STL
- ONT
1 stop6h 11m
Frontier
Deal found 6/4![Frontier logo]()
$157
This Super.com deal was found by Cheapflights users on 6/7. 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 Super.com 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 6/7![Frontier logo]()
$158
This Super.com deal was found by Cheapflights users on 6/7. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/227:03 pm
STL
- ONT
1 stop15h 00m
Frontier
Deal found 6/7![Frontier logo]()
$159
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 June 7, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $191 (Kiwi.com) |
One-way from | $127 (Trip.com) |
Popular in | March |
Cheapest in | November |
Average price | $358 |
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 June 7, 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
Tue 9/1
8:08 pm-11:49 pm
1 stop5h 41m
Ontario
Wed 9/2
6:00 am-7:23 pm
1 stop11h 23m
$264
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Sun 6/28
2:56 pm-3:08 pm
1 stop26h 12m
Ontario
Sun 7/5
3:40 pm-6:15 pm
1 stop24h 35m
$360
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Tue 6/23
8:08 pm-11:49 pm
1 stop5h 41m
Ontario
Wed 6/24
3:34 pm-2:06 pm
1 stop20h 32m
$362
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Fri 7/3
2:56 pm-7:51 pm
1 stop6h 55m
Ontario
Mon 7/6
10:49 am-7:23 pm
1 stop6h 34m
$392
Quickest round-trip
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Sun 8/30
8:00 am-12:05 pm
1 stop6h 05m
Ontario
Sun 8/30
5:05 pm-12:41 am
1 stop5h 36m
$477
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Wed 8/26
5:10 am-8:01 pm
2 stops16h 51m
Ontario
Wed 9/2
5:00 am-10:00 pm
2 stops15h 00m
$539
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Wed 8/26
5:10 am-8:01 pm
2 stops16h 51m
Ontario
Tue 9/1
5:00 am-10:00 pm
2 stops15h 00m
$539
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Tue 9/1
8:00 am-8:01 pm
2 stops14h 01m
Ontario
Wed 9/2
6:00 am-4:34 pm
2 stops8h 34m
$554
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Tue 8/11
1:36 pm-8:01 pm
2 stops8h 25m
Ontario
Wed 8/12
5:00 am-12:40 pm
1 stop5h 40m
$556
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Mon 7/6
3:35 pm-10:15 pm
2 stops8h 40m
Ontario
Mon 7/13
6:30 am-4:30 pm
2 stops8h 00m
$558
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 June.
| 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 Accuracy1 star | Trust Score*3 stars | |
| Price Accuracy- | Trust Score*1 star | |
| Price Accuracy3 stars | 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 March is currently the most expensive (average of $430). 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?
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 June 7, 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.
Boarding
8.1
Food
7.0
Crew
8.6
Entertainment
7.5
Comfort
8.0
Overall
8.0
Reviews
1 / 20
10.0
ExcellentWalter,May 2026
LAS - BUR
Boarding
8.1
Food
7.0
Crew
8.6
Entertainment
7.5
Comfort
8.0
Overall
8.0
Reviews
1 / 20
10.0
ExcellentWalter,May 2026
LAS - BUR
Boarding
8.1
Food
7.0
Crew
8.6
Entertainment
7.5
Comfort
8.0
Overall
8.0
Reviews
1 / 20
10.0
ExcellentWalter,May 2026
LAS - BUR
Boarding
8.1
Food
7.0
Crew
8.6
Entertainment
7.5
Comfort
8.0
Overall
8.0
Reviews
1 / 20
10.0
ExcellentWalter,May 2026
LAS - BUR
Boarding
8.1
Food
7.0
Crew
8.6
Entertainment
7.5
Comfort
8.0
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 June 7, 2026.
St. Louis and Ontario flights
Browse other St. Louis and Ontario flight options. Last updated on June 7, 2026.
Other flights from St. Louis
Browse through other flights departing from St. Louis. Flights are based on user searches made on Cheapflights and were last updated on June 7, 2026.
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Check out other popular destinations found by fellow travelers in 2026
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 June 7, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$143 | Average$255 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$201 | Average$510 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$264 | Average$323 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$292 | Average$436 | FlexibilityNo cancel fee | On-time63% |