$85+ 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 5/26. Fares are subject to change and may not be available on all flights or dates of travel.
STL — ONT
May 28 — Jun 41
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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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 April 28, 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 April 28, 2026.
This Booking.com deal was found by Cheapflights users on 4/24. 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.
Tue 5/196:51 pm
STL
- ONT
1 stop22h 53m
Frontier
Sun 5/2410:50 am
ONT
- STL
1 stop6h 33m
Frontier
Deal found 4/24![Frontier logo]()
$167
This Booking.com deal was found by Cheapflights users on 4/23. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/159:18 pm
STL
- ONT
1 stop19h 51m
Frontier
Wed 5/204:39 pm
ONT
- STL
1 stop25h 32m
Frontier
Deal found 4/23![Frontier logo]()
$172
This CheapOair deal was found by Cheapflights users on 4/23. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/238:08 pm
STL
- ONT
1 stop15h 57m
Frontier
Sat 5/3010:50 am
ONT
- STL
1 stop6h 33m
Frontier
Deal found 4/23![Frontier logo]()
$185
This Booking.com deal was found by Cheapflights users on 4/26. 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 5/266:51 pm
STL
- ONT
1 stop15h 13m
Frontier
Tue 6/26:00 am
ONT
- STL
1 stop11h 23m
Frontier
Deal found 4/26![Frontier logo]()
$187
This Super.com deal was found by Cheapflights users on 4/28. 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 5/236:30 pm
STL
- ONT
1 stop15h 34m
Frontier
Wed 5/2710:50 am
ONT
- STL
1 stop6h 33m
Frontier
Deal found 4/28![Frontier logo]()
$191
This Booking.com deal was found by Cheapflights users on 4/24. 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.
Tue 5/126:51 pm
STL
- ONT
1 stop22h 53m
Frontier
Mon 5/1811:36 am
ONT
- STL
1 stop28h 30m
Frontier
Deal found 4/24![Frontier logo]()
$193
This Expedia deal was found by Cheapflights users on 4/23. 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/712:36 pm
STL
- ONT
1 stop21h 13m
Frontier
Sun 5/106:00 am
ONT
- STL
1 stop11h 23m
Frontier
Deal found 4/23![Frontier logo]()
$205
This Gotogate deal was found by Cheapflights users on 4/27. 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.
Mon 6/19:21 pm
STL
- ONT
1 stop20h 23m
Frontier
Sun 6/76:00 am
ONT
- STL
1 stop11h 23m
Frontier
Deal found 4/27![Frontier logo]()
$210
This CheapOair deal was found by Cheapflights users on 4/24. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/89:18 pm
STL
- ONT
1 stop19h 51m
Frontier
Mon 5/1111:36 am
ONT
- STL
1 stop28h 30m
Frontier
Deal found 4/24![Frontier logo]()
$211
This Booking.com deal was found by Cheapflights users on 4/26. 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 5/136:51 pm
STL
- ONT
1 stop22h 18m
Frontier
Wed 5/2710:50 am
ONT
- STL
1 stop6h 33m
Frontier
Deal found 4/26![Frontier logo]()
$212
This Booking.com deal was found by Cheapflights users on 4/28. 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 6/19:21 pm
STL
- ONT
1 stop20h 23m
Frontier
Thu 6/411:51 am
ONT
- STL
1 stop6h 20m
Frontier
Deal found 4/28![Frontier logo]()
$217
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 April 28, 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 April 28, 2026.
This Frontier deal was found by Cheapflights users on 4/27. 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 6/202:56 pm
STL
- ONT
1 stop6h 55m
Frontier
Tue 6/236:00 am
ONT
- STL
1 stop11h 23m
Frontier
Deal found 4/27![Frontier logo]()
$270
This Delta deal was found by Cheapflights users on 4/26. 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.
Wed 8/266:00 am
STL
- ONT
1 stop7h 04m
Delta
Mon 8/3110:59 pm
ONT
- STL
1 stop7h 07m
Delta
Deal found 4/26![Delta logo]()
$444
This Southwest deal was found by Cheapflights users on 4/23. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 6/15:45 am
STL
- ONT
2 stops9h 10m
Southwest
Sat 6/65:30 am
ONT
- STL
2 stops8h 25m
Southwest
Deal found 4/23![Southwest logo]()
$452
This Alaska Airlines deal was found by Cheapflights users on 4/24. 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.
Fri 10/23:17 pm
STL
- ONT
1 stop10h 07m
Alaska Airlines
Tue 10/612:00 pm
ONT
- STL
1 stop9h 59m
Alaska Airlines
Deal found 4/24![Alaska Airlines logo]()
$477
This Frontier deal was found by Cheapflights users on 4/27. 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 6/152:56 pm
STL
- ONT
1 stop6h 55m
Frontier
Tue 6/236:00 am
ONT
- STL
1 stop11h 23m
Frontier
Deal found 4/27![Frontier logo]()
$270
This CheapOair deal was found by Cheapflights users on 4/25. 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 7/62:52 pm
STL
- ONT
1 stop26h 15m
Frontier
Tue 7/141:28 pm
ONT
- STL
1 stop26h 37m
Frontier
Deal found 4/25![Frontier logo]()
$325
This Delta deal was found by Cheapflights users on 4/26. 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 8/243:42 pm
STL
- ONT
1 stop8h 14m
Delta
Tue 9/110:59 pm
ONT
- STL
1 stop7h 07m
Delta
Deal found 4/26![Delta logo]()
$444
This Southwest deal was found by Cheapflights users on 4/23. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/25:30 am
STL
- ONT
2 stops8h 05m
Southwest
Sun 6/72:35 pm
ONT
- STL
2 stops7h 20m
Southwest
Deal found 4/23![Southwest logo]()
$462
This Alaska Airlines deal was found by Cheapflights users on 4/23. 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 Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/237:00 am
STL
- ONT
1 stop9h 47m
Alaska Airlines
Sun 11/112:00 pm
ONT
- STL
1 stop9h 59m
Alaska Airlines
Deal found 4/23![Alaska Airlines logo]()
$477
This Southwest deal was found by Cheapflights users on 4/25. 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.
Fri 10/232:55 pm
STL
- ONT
1 stop6h 55m
Southwest
Sun 11/112:40 pm
ONT
- STL
1 stop7h 55m
Southwest
Deal found 4/25![Southwest logo]()
$477
This Delta deal was found by Cheapflights users on 4/27. 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 8/306:59 pm
STL
- ONT
1 stop6h 45m
Delta
Mon 9/149:55 am
ONT
- STL
1 stop6h 05m
Delta
Deal found 4/27![Delta logo]()
$477
This Alaska Airlines deal was found by Cheapflights users on 4/25. 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.
Wed 9/23:00 pm
STL
- ONT
1 stop10h 24m
Alaska Airlines
Sun 9/611:58 am
ONT
- STL
1 stop10h 01m
Alaska Airlines
Deal found 4/25![Alaska Airlines logo]()
$477
Last-minute flights from St. Louis to OntarioDiscover last-minute flight deals from St. Louis to Ontario. Data last updated April 28, 2026 and is based on user searches.
Discover last-minute flight deals from St. Louis to Ontario. Data last updated April 28, 2026 and is based on user searches.
This Expedia deal was found by Cheapflights users on 4/23. 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/712:36 pm
STL
- ONT
1 stop21h 13m
Frontier
Sun 5/106:00 am
ONT
- STL
1 stop11h 23m
Frontier
Deal found 4/23![Frontier logo]()
$205
This CheapOair deal was found by Cheapflights users on 4/24. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/89:18 pm
STL
- ONT
1 stop19h 51m
Frontier
Mon 5/1111:36 am
ONT
- STL
1 stop28h 30m
Frontier
Deal found 4/24![Frontier logo]()
$211
This Booking.com deal was found by Cheapflights users on 4/24. 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.
Tue 5/126:51 pm
STL
- ONT
1 stop22h 53m
Frontier
Mon 5/1811:36 am
ONT
- STL
1 stop28h 30m
Frontier
Deal found 4/24![Frontier logo]()
$193
This Booking.com deal was found by Cheapflights users on 4/26. 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 5/136:51 pm
STL
- ONT
1 stop22h 18m
Frontier
Wed 5/2710:50 am
ONT
- STL
1 stop6h 33m
Frontier
Deal found 4/26![Frontier logo]()
$212
This Booking.com deal was found by Cheapflights users on 4/23. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/159:18 pm
STL
- ONT
1 stop19h 51m
Frontier
Wed 5/204:39 pm
ONT
- STL
1 stop25h 32m
Frontier
Deal found 4/23![Frontier logo]()
$172
This Booking.com deal was found by Cheapflights users on 4/26. 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 5/159:18 pm
STL
- ONT
1 stop19h 51m
Frontier
Sun 5/174:04 pm
ONT
- STL
1 stop26h 19m
Frontier
Deal found 4/26![Frontier logo]()
$218
This Booking.com deal was found by Cheapflights users on 4/24. 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.
Tue 5/196:51 pm
STL
- ONT
1 stop22h 53m
Frontier
Sun 5/2410:50 am
ONT
- STL
1 stop6h 33m
Frontier
Deal found 4/24![Frontier logo]()
$167
This CheapOair deal was found by Cheapflights users on 4/23. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/238:08 pm
STL
- ONT
1 stop15h 57m
Frontier
Sat 5/3010:50 am
ONT
- STL
1 stop6h 33m
Frontier
Deal found 4/23![Frontier logo]()
$185
This Super.com deal was found by Cheapflights users on 4/28. 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 5/236:30 pm
STL
- ONT
1 stop15h 34m
Frontier
Wed 5/2710:50 am
ONT
- STL
1 stop6h 33m
Frontier
Deal found 4/28![Frontier logo]()
$191
This Booking.com deal was found by Cheapflights users on 4/26. 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 5/266:51 pm
STL
- ONT
1 stop15h 13m
Frontier
Tue 6/26:00 am
ONT
- STL
1 stop11h 23m
Frontier
Deal found 4/26![Frontier logo]()
$187
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 April 28, 2026.
Search for one-way flight options from St. Louis to Ontario. Find affordable one-way fares based on user searches. Data last updated April 28, 2026.
This Super.com deal was found by Cheapflights users on 4/28. 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 5/266:51 pm
STL
- ONT
1 stop15h 13m
Frontier
Deal found 4/28![Frontier logo]()
$85
This Jettzy deal was found by Cheapflights users on 4/26. 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 Jettzy is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/236:30 pm
STL
- ONT
1 stop15h 34m
Frontier
Deal found 4/26![Frontier logo]()
$86
This Super.com deal was found by Cheapflights users on 4/27. 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 5/119:18 pm
STL
- ONT
1 stop20h 26m
Frontier
Deal found 4/27![Frontier logo]()
$105
This Booking.com deal was found by Cheapflights users on 4/24. 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.
Tue 5/126:51 pm
STL
- ONT
1 stop22h 53m
Frontier
Deal found 4/24![Frontier logo]()
$106
This Super.com deal was found by Cheapflights users on 4/24. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/276:51 pm
STL
- ONT
1 stop15h 13m
Frontier
Deal found 4/24![Frontier logo]()
$110
This Kiwi.com deal was found by Cheapflights users on 4/24. 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.
Fri 5/159:18 pm
STL
- ONT
2 stops14h 47m
Frontier
Deal found 4/24![Frontier logo]()
$111
This Super.com deal was found by Cheapflights users on 4/26. 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 6/212:56 pm
STL
- ONT
1 stop6h 55m
Frontier
Deal found 4/26![Frontier logo]()
$124
This Booking.com deal was found by Cheapflights users on 4/27. 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 5/168:08 pm
STL
- ONT
1 stop5h 41m
Frontier
Deal found 4/27![Frontier logo]()
$127
This Super.com deal was found by Cheapflights users on 4/27. 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 5/48:17 pm
STL
- ONT
1 stop15h 48m
Frontier
Deal found 4/27![Frontier logo]()
$129
This Super.com deal was found by Cheapflights users on 4/28. 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 5/56:51 pm
STL
- ONT
1 stop22h 53m
Frontier
Deal found 4/28![Frontier logo]()
$130
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 April 28, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $167 (Booking.com) |
One-way from | $85 (Super.com) |
Popular in | March |
Cheapest in | November |
Average price | $306 |
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 April 28, 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
Sat 6/20
2:56 pm-7:51 pm
1 stop6h 55m
Ontario
Tue 6/23
6:00 am-7:23 pm
1 stop11h 23m
$270
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Mon 6/15
2:56 pm-7:51 pm
1 stop6h 55m
Ontario
Tue 6/23
6:00 am-7:23 pm
1 stop11h 23m
$270
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Mon 7/6
2:52 pm-3:07 pm
1 stop26h 15m
Ontario
Tue 7/14
1:28 pm-6:05 pm
1 stop26h 37m
$325
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Wed 8/26
6:00 am-11:04 am
1 stop7h 04m
Ontario
Mon 8/31
10:59 pm-8:06 am
1 stop7h 07m
$444
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Mon 8/24
3:42 pm-9:56 pm
1 stop8h 14m
Ontario
Tue 9/1
10:59 pm-8:06 am
1 stop7h 07m
$444
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Mon 6/1
5:45 am-12:55 pm
2 stops9h 10m
Ontario
Sat 6/6
5:30 am-3:55 pm
2 stops8h 25m
$452
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Tue 6/2
5:30 am-11:35 am
2 stops8h 05m
Ontario
Sun 6/7
2:35 pm-11:55 pm
2 stops7h 20m
$462
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Fri 10/2
3:17 pm-11:24 pm
1 stop10h 07m
Ontario
Tue 10/6
12:00 pm-11:59 pm
1 stop9h 59m
$477
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Fri 10/23
7:00 am-2:47 pm
1 stop9h 47m
Ontario
Sun 11/1
12:00 pm-11:59 pm
1 stop9h 59m
$477
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Fri 10/23
2:55 pm-7:50 pm
1 stop6h 55m
Ontario
Sun 11/1
12:40 pm-10:35 pm
1 stop7h 55m
$477
Showing 1-10 of 21 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 April.
| 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 Accuracy2 stars | Trust Score*1 star | |
| 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 40% 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 $245.
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 April 28, 2026.
Peruse reviews from past customers who have flown with Southwest,Delta, andUnited 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.
Food
7.0
Boarding
8.1
Entertainment
7.5
Comfort
8.0
Crew
8.6
Overall
8.0
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Food
7.0
Boarding
8.1
Entertainment
7.5
Comfort
8.0
Crew
8.6
Overall
8.0
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Food
7.0
Boarding
8.1
Entertainment
7.5
Comfort
8.0
Crew
8.6
Overall
8.0
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Food
7.0
Boarding
8.1
Entertainment
7.5
Comfort
8.0
Crew
8.6
Overall
8.0
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Food
7.0
Boarding
8.1
Entertainment
7.5
Comfort
8.0
Crew
8.6
Overall
8.0
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Food
7.0
Boarding
8.1
Entertainment
7.5
Comfort
8.0
Crew
8.6
Overall
8.0
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
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 April 28, 2026.
St. Louis and Ontario flights
Browse other St. Louis and Ontario flight options. Last updated on April 28, 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 April 28, 2026.
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Check out other popular destinations found by fellow travelers in 2026
Top 5 airlines flying from St. Louis to Ontario
Discover the top 5 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 April 28, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$128 | Average$249 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$264 | Average$328 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$276 | Average$431 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$292 | Average$422 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$292 | Average$446 | FlexibilityNo cancel fee | On-time69% |