$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 3/30. Fares are subject to change and may not be available on all flights or dates of travel.
STL — ONT
Apr 9 — Apr 161
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 March 10, 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 March 10, 2026.
This Expedia deal was found by Cheapflights users on 3/9. 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/18:16 pm
STL
- ONT
1 stop5h 40m
Frontier
Thu 4/1611:47 am
ONT
- STL
1 stop7h 13m
Frontier
Deal found 3/9![Frontier logo]()
$190
This Frontier deal was found by Cheapflights users on 3/9. 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 5/28:17 pm
STL
- ONT
1 stop13h 09m
Frontier
Fri 5/812:59 am
ONT
- STL
1 stop16h 13m
Frontier
Deal found 3/9![Frontier logo]()
$191
This Booking.com deal was found by Cheapflights users on 3/9. 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 4/88:16 pm
STL
- ONT
1 stop5h 40m
Frontier
Wed 4/157:44 pm
ONT
- STL
1 stop23h 16m
Frontier
Deal found 3/9![Frontier logo]()
$197
This CheapOair deal was found by Cheapflights users on 3/6. 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.
Thu 4/238:06 pm
STL
- ONT
1 stop13h 25m
Frontier
Fri 4/2412:59 am
ONT
- STL
1 stop16h 33m
Frontier
Deal found 3/6![Frontier logo]()
$201
This Booking.com deal was found by Cheapflights users on 3/9. 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.
Sun 4/199:55 pm
STL
- ONT
1 stop24h 09m
Frontier
Fri 5/112:59 am
ONT
- STL
1 stop16h 33m
Frontier
Deal found 3/9![Frontier logo]()
$203
This Gotogate deal was found by Cheapflights users on 3/7. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/210:12 pm
STL
- ONT
1 stop11h 52m
Frontier
Tue 4/76:20 am
ONT
- STL
1 stop25h 28m
Frontier
Deal found 3/7![Frontier logo]()
$214
This Booking.com deal was found by Cheapflights users on 3/5. 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.
Wed 4/18:16 pm
STL
- ONT
1 stop5h 40m
Frontier
Tue 4/76:20 am
ONT
- STL
1 stop25h 28m
Frontier
Deal found 3/5![Frontier logo]()
$218
This Frontier deal was found by Cheapflights users on 3/9. 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.
Sun 4/510:12 pm
STL
- ONT
1 stop11h 52m
Frontier
Wed 4/810:03 pm
ONT
- STL
1 stop12h 16m
Frontier
Deal found 3/9![Frontier logo]()
$220
This CheapOair deal was found by Cheapflights users on 3/5. 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.
Thu 4/168:06 pm
STL
- ONT
1 stop13h 25m
Frontier
Sun 4/1912:59 am
ONT
- STL
1 stop16h 33m
Frontier
Deal found 3/5![Frontier logo]()
$222
This Booking.com deal was found by Cheapflights users on 3/5. 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.
Sun 4/199:55 pm
STL
- ONT
1 stop14h 19m
Frontier
Sat 4/2512:59 am
ONT
- STL
1 stop16h 22m
Frontier
Deal found 3/5![Frontier logo]()
$223
This CheapOair deal was found by Cheapflights users on 3/5. 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.
Thu 3/268:06 pm
STL
- ONT
1 stop14h 00m
Frontier
Tue 3/316:15 am
ONT
- STL
1 stop25h 33m
Frontier
Deal found 3/5![Frontier logo]()
$225
This Gotogate deal was found by Cheapflights users on 3/7. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 3/258:12 pm
STL
- ONT
1 stop5h 47m
Frontier
Sun 4/56:20 am
ONT
- STL
1 stop25h 28m
Frontier
Deal found 3/7![Frontier logo]()
$226
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 March 10, 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 March 10, 2026.
This Delta deal was found by Cheapflights users on 3/7. 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 4/26:12 pm
STL
- ONT
1 stop7h 39m
Delta
Mon 4/610:25 pm
ONT
- STL
1 stop8h 40m
Delta
Deal found 3/7![Delta logo]()
$313
This Alaska Airlines deal was found by Cheapflights users on 3/6. 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 Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/13:50 pm
STL
- ONT
1 stop10h 09m
Alaska Airlines
Mon 4/67:08 pm
ONT
- STL
1 stop26h 51m
Alaska Airlines
Deal found 3/6![Alaska Airlines logo]()
$368
This American Airlines deal was found by Cheapflights users on 3/5. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/25:12 am
STL
- ONT
1 stop6h 54m
American Airlines
Fri 4/1012:19 pm
ONT
- STL
2 stops8h 40m
American Airlines
Deal found 3/5![American Airlines logo]()
$390
This United Airlines deal was found by Cheapflights users on 3/7. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/48:54 am
STL
- ONT
2 stops10h 53m
United Airlines
Sat 4/116:49 pm
ONT
- STL
1 stop9h 01m
United Airlines
Deal found 3/7![United Airlines logo]()
$410
This Delta deal was found by Cheapflights users on 3/7. 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 4/26:12 pm
STL
- ONT
1 stop7h 39m
Delta
Tue 4/712:57 pm
ONT
- STL
1 stop9h 01m
Delta
Deal found 3/7![Delta logo]()
$313
This Delta deal was found by Cheapflights users on 3/9. 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 3/317:15 am
STL
- ONT
1 stop7h 08m
Delta
Sun 4/56:00 am
ONT
- STL
1 stop5h 17m
Delta
Deal found 3/9![Delta logo]()
$313
This Delta deal was found by Cheapflights users on 3/7. 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.
Wed 5/137:59 pm
STL
- ONT
1 stop5h 35m
Delta
Sat 5/1612:08 pm
ONT
- STL
1 stop7h 21m
Delta
Deal found 3/7![Delta logo]()
$317
This Delta deal was found by Cheapflights users on 3/8. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/226:45 pm
STL
- ONT
1 stop6h 59m
Delta
Mon 4/2710:15 pm
ONT
- STL
1 stop8h 15m
Delta
Deal found 3/8![Delta logo]()
$348
This Delta deal was found by Cheapflights users on 3/7. 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.
Tue 5/127:59 pm
STL
- ONT
1 stop5h 35m
Delta
Fri 5/154:57 pm
ONT
- STL
1 stop5h 33m
Delta
Deal found 3/7![Delta logo]()
$387
This Delta deal was found by Cheapflights users on 3/9. 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.
Wed 5/206:00 am
STL
- ONT
1 stop6h 57m
Delta
Mon 5/2510:00 pm
ONT
- STL
1 stop9h 44m
Delta
Deal found 3/9![Delta logo]()
$387
This Delta deal was found by Cheapflights users on 3/9. 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.
Thu 5/217:00 am
STL
- ONT
1 stop7h 19m
Delta
Mon 5/2510:00 pm
ONT
- STL
1 stop8h 18m
Delta
Deal found 3/9![Delta logo]()
$457
This Delta deal was found by Cheapflights users on 3/6. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 5/177:59 pm
STL
- ONT
1 stop5h 35m
Delta
Wed 5/204:57 pm
ONT
- STL
1 stop5h 33m
Delta
Deal found 3/6![Delta logo]()
$458
Last-minute flights from St. Louis to OntarioDiscover last-minute flight deals from St. Louis to Ontario. Data last updated March 10, 2026 and is based on user searches.
Discover last-minute flight deals from St. Louis to Ontario. Data last updated March 10, 2026 and is based on user searches.
This Gotogate deal was found by Cheapflights users on 3/7. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 3/258:12 pm
STL
- ONT
1 stop5h 47m
Frontier
Sun 4/56:20 am
ONT
- STL
1 stop25h 28m
Frontier
Deal found 3/7![Frontier logo]()
$226
This CheapOair deal was found by Cheapflights users on 3/5. 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.
Thu 3/268:06 pm
STL
- ONT
1 stop14h 00m
Frontier
Tue 3/316:15 am
ONT
- STL
1 stop25h 33m
Frontier
Deal found 3/5![Frontier logo]()
$225
This Expedia deal was found by Cheapflights users on 3/9. 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/18:16 pm
STL
- ONT
1 stop5h 40m
Frontier
Thu 4/1611:47 am
ONT
- STL
1 stop7h 13m
Frontier
Deal found 3/9![Frontier logo]()
$190
This Booking.com deal was found by Cheapflights users on 3/5. 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.
Wed 4/18:16 pm
STL
- ONT
1 stop5h 40m
Frontier
Tue 4/76:20 am
ONT
- STL
1 stop25h 28m
Frontier
Deal found 3/5![Frontier logo]()
$218
This Booking.com deal was found by Cheapflights users on 3/9. 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 4/18:16 pm
STL
- ONT
1 stop5h 40m
Frontier
Sun 4/56:20 am
ONT
- STL
1 stop25h 28m
Frontier
Deal found 3/9![Frontier logo]()
$227
This Gotogate deal was found by Cheapflights users on 3/7. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/210:12 pm
STL
- ONT
1 stop11h 52m
Frontier
Tue 4/76:20 am
ONT
- STL
1 stop25h 28m
Frontier
Deal found 3/7![Frontier logo]()
$214
This Frontier deal was found by Cheapflights users on 3/9. 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.
Sun 4/510:12 pm
STL
- ONT
1 stop11h 52m
Frontier
Wed 4/810:03 pm
ONT
- STL
1 stop12h 16m
Frontier
Deal found 3/9![Frontier logo]()
$220
This Booking.com deal was found by Cheapflights users on 3/9. 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 4/88:16 pm
STL
- ONT
1 stop5h 40m
Frontier
Wed 4/157:44 pm
ONT
- STL
1 stop23h 16m
Frontier
Deal found 3/9![Frontier logo]()
$197
This CheapOair deal was found by Cheapflights users on 3/5. 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.
Thu 4/168:06 pm
STL
- ONT
1 stop13h 25m
Frontier
Sun 4/1912:59 am
ONT
- STL
1 stop16h 33m
Frontier
Deal found 3/5![Frontier logo]()
$222
This Booking.com deal was found by Cheapflights users on 3/9. 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.
Sun 4/199:55 pm
STL
- ONT
1 stop24h 09m
Frontier
Fri 5/112:59 am
ONT
- STL
1 stop16h 33m
Frontier
Deal found 3/9![Frontier logo]()
$203
This Booking.com deal was found by Cheapflights users on 3/5. 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.
Sun 4/199:55 pm
STL
- ONT
1 stop14h 19m
Frontier
Sat 4/2512:59 am
ONT
- STL
1 stop16h 22m
Frontier
Deal found 3/5![Frontier logo]()
$223
This CheapOair deal was found by Cheapflights users on 3/6. 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.
Thu 4/238:06 pm
STL
- ONT
1 stop13h 25m
Frontier
Fri 4/2412:59 am
ONT
- STL
1 stop16h 33m
Frontier
Deal found 3/6![Frontier logo]()
$201
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 March 10, 2026.
Search for one-way flight options from St. Louis to Ontario. Find affordable one-way fares based on user searches. Data last updated March 10, 2026.
This Kiwi.com deal was found by Cheapflights users on 3/9. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 3/308:12 pm
STL
- ONT
1 stop29h 47m
Frontier
Deal found 3/9![Frontier logo]()
$85
This Super.com deal was found by Cheapflights users on 3/9. 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.
Wed 3/258:12 pm
STL
- ONT
1 stop5h 47m
Frontier
Deal found 3/9![Frontier logo]()
$94
This Frontier deal was found by Cheapflights users on 3/7. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/88:16 pm
STL
- ONT
1 stop5h 40m
Frontier
Deal found 3/7![Frontier logo]()
$95
This Super.com deal was found by Cheapflights users on 3/9. 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.
Thu 4/169:55 pm
STL
- ONT
1 stop12h 29m
Frontier
Deal found 3/9![Frontier logo]()
$99
This Super.com deal was found by Cheapflights users on 3/10. 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.
Mon 5/113:02 pm
STL
- ONT
1 stop10h 22m
Frontier
Deal found 3/10![Frontier logo]()
$100
This Booking.com deal was found by Cheapflights users on 3/5. 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.
Fri 4/179:55 pm
STL
- ONT
1 stop14h 49m
Frontier
Deal found 3/5![Frontier logo]()
$101
This Super.com deal was found by Cheapflights users on 3/10. 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.
Sun 5/109:55 pm
STL
- ONT
1 stop12h 09m
Frontier
Deal found 3/10![Frontier logo]()
$109
This Kiwi.com deal was found by Cheapflights users on 3/5. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 3/3112:14 pm
STL
- ONT
1 stop29h 43m
Frontier
Deal found 3/5![Frontier logo]()
$110
This Super.com deal was found by Cheapflights users on 3/6. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 3/188:12 pm
STL
- ONT
1 stop5h 47m
Frontier
Deal found 3/6![Frontier logo]()
$115
This Super.com deal was found by Cheapflights users on 3/9. 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 3/178:06 pm
STL
- ONT
1 stop19h 22m
Frontier
Deal found 3/9![Frontier logo]()
$120
This CheapOair deal was found by Cheapflights users on 3/9. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/249:58 pm
STL
- ONT
1 stop22h 51m
Frontier
Deal found 3/9![Frontier logo]()
$122
This Super.com deal was found by Cheapflights users on 3/9. 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.
Thu 4/210:12 pm
STL
- ONT
1 stop11h 52m
Frontier
Deal found 3/9![Frontier logo]()
$123
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 March 10, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $190 (Expedia) |
One-way from | $85 (Kiwi.com) |
Popular in | March |
Cheapest in | November |
Average price | $436 |
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 March 10, 2026.
Use the filters below to find and compare flights from St. Louis to Ontario that are best for you.
Fly from
Fly to
Route
Depart
Return
Cheapest round-trip
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Thu 4/2
6:12 pm-11:51 pm
1 stop7h 39m
Ontario
Mon 4/6
10:25 pm-9:05 am
1 stop8h 40m
$313
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Thu 4/2
6:12 pm-11:51 pm
1 stop7h 39m
Ontario
Tue 4/7
12:57 pm-11:58 pm
1 stop9h 01m
$313
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Tue 3/31
7:15 am-12:23 pm
1 stop7h 08m
Ontario
Sun 4/5
6:00 am-1:17 pm
1 stop5h 17m
$313
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Wed 5/13
7:59 pm-11:34 pm
1 stop5h 35m
Ontario
Sat 5/16
12:08 pm-9:29 pm
1 stop7h 21m
$317
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Wed 4/22
6:45 pm-11:44 pm
1 stop6h 59m
Ontario
Mon 4/27
10:15 pm-8:30 am
1 stop8h 15m
$348
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Wed 4/1
3:50 pm-11:59 pm
1 stop10h 09m
Ontario
Mon 4/6
7:08 pm-11:59 pm
1 stop26h 51m
$368
Quickest round-trip
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Tue 5/12
7:59 pm-11:34 pm
1 stop5h 35m
Ontario
Fri 5/15
4:57 pm-12:30 am
1 stop5h 33m
$387
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Wed 5/20
6:00 am-10:57 am
1 stop6h 57m
Ontario
Mon 5/25
10:00 pm-9:44 am
1 stop9h 44m
$387
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Thu 4/2
5:12 am-10:06 am
1 stop6h 54m
Ontario
Fri 4/10
12:19 pm-10:59 pm
2 stops8h 40m
$390
St. LouisOntario
STL - ONT
STLONT
Lambert-St Louis
Sat 4/4
8:54 am-5:47 pm
2 stops10h 53m
Ontario
Sat 4/11
6:49 pm-5:50 am
1 stop9h 01m
$410
Showing 1-10 of 23 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 March.
| Provider | Price Accuracy | Trust Score* |
|---|---|---|
| Price Accuracy1 star | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy1 star | Trust Score*3 stars | |
| Price Accuracy- | Trust Score*1 star | |
| Price Accuracy- | Trust Score*1 star | |
| Price Accuracy2 stars | Trust Score*2 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
How far ahead should I book a flight from St. Louis to Ontario?
Use this chart to determine the optimal time to book a round-trip flight from St. Louis to Ontario. Price data was last updated on March 6, 2026.
The price you pay for your flight from St. Louis to Ontario may vary depending on when you book. For the best chance of a lower fare, look to book 65 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.
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 $67). Flying from St. Louis to Ontario in June is currently the most expensive (average of $250). 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.
Phoenix (PHX) – chosen by Cheapflights users on 33% 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.
Phoenix (PHX) is the most affordable 1-stop option, with an average round-trip price of $305.
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 March 10, 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.
Boarding
8.1
Food
7.0
Entertainment
7.5
Crew
8.6
Overall
8.0
Comfort
8.0
Reviews
1 / 20
8.0
ExcellentWalter,Aug 2025
OAK - SAN
Boarding
8.1
Food
7.0
Entertainment
7.5
Crew
8.6
Overall
8.0
Comfort
8.0
Reviews
1 / 20
8.0
ExcellentWalter,Aug 2025
OAK - SAN
Boarding
8.1
Food
7.0
Entertainment
7.5
Crew
8.6
Overall
8.0
Comfort
8.0
Reviews
1 / 20
8.0
ExcellentWalter,Aug 2025
OAK - SAN
Boarding
8.1
Food
7.0
Entertainment
7.5
Crew
8.6
Overall
8.0
Comfort
8.0
Reviews
1 / 20
8.0
ExcellentWalter,Aug 2025
OAK - SAN
Boarding
8.1
Food
7.0
Entertainment
7.5
Crew
8.6
Overall
8.0
Comfort
8.0
Reviews
1 / 20
8.0
ExcellentWalter,Aug 2025
OAK - SAN
Boarding
8.1
Food
7.0
Entertainment
7.5
Crew
8.6
Overall
8.0
Comfort
8.0
Reviews
1 / 20
8.0
ExcellentWalter,Aug 2025
OAK - SAN
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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Complete your trip
Complete your trip to Ontario by adding a car rental and/or hotel reservation to your travel itinerary.
Search flights from St. Louis to Ontario by cabin class
Find flights from St. Louis to Ontario, based on your preferred cabin class, be it economy, premium economy, business, or first class.
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 March 10, 2026.
St. Louis and Ontario flights
Browse other St. Louis and Ontario flight options. Last updated on March 10, 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 March 10, 2026.
Popular flight searches
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 March 10, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$128 | Average$238 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$190 | Average$362 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$265 | Average$346 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$292 | Average$398 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$292 | Average$429 | FlexibilityNo cancel fee | On-time69% |