$135+ Cheap flights from St. Louis (STL) to Ontario
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 10/15. Fares are subject to change and may not be available on all flights or dates of travel.
STL — YYZ
Sep 3 — Sep 101
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
We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.3. Compare prices and book
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 August 4, 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 August 4, 2026.
This Kiwi.com deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/2610:35 am -
2 stops12h 50m
Wed 10/285:15 pm -
1 stop27h 24m
Deal found 7/31![Multiple Airlines logo]()
$344
This American Airlines deal was found by Cheapflights users on 7/30. 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 8/246:00 am -
1 stop7h 33m
Mon 8/311:15 pm -
1 stop11h 59m
Deal found 7/30![American Airlines logo]()
$352
This Kiwi.com deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/302:29 pm -
2 stops29h 26m
Mon 10/57:45 am -
1 stop9h 49m
Deal found 7/31![Multiple Airlines logo]()
$364
This American Airlines deal was found by Cheapflights users on 7/31. 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.
Fri 10/307:29 am -
1 stop9h 16m
Mon 11/27:09 am -
1 stop10h 34m
Deal found 7/31![American Airlines logo]()
$369
This Kiwi.com deal was found by Cheapflights users on 8/2. 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.
Fri 9/112:29 pm -
2 stops22h 36m
Thu 9/179:50 am -
1 stop7h 34m
Deal found 8/2![Multiple Airlines logo]()
$376
This American Airlines deal was found by Cheapflights users on 8/4. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/115:00 am -
1 stop8h 32m
Thu 9/173:13 pm -
1 stop10h 14m
Deal found 8/4![American Airlines logo]()
$382
This American Airlines deal was found by Cheapflights users on 8/2. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/16:00 am -
1 stop11h 30m
Tue 9/811:39 am -
1 stop8h 48m
Deal found 8/2![American Airlines logo]()
$386
This Kiwi.com deal was found by Cheapflights users on 8/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/198:34 pm -
1 stop16h 56m
Sat 10/249:30 am -
2 stops25h 10m
Deal found 8/1![Multiple Airlines logo]()
$388
This American Airlines deal was found by Cheapflights users on 8/2. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/165:00 am -
1 stop8h 32m
Wed 9/2311:40 am -
1 stop10h 04m
Deal found 8/2![American Airlines logo]()
$396
This Kiwi.com deal was found by Cheapflights users on 8/3. 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.
Thu 11/510:35 am -
2 stops12h 35m
Sun 11/86:30 am -
1 stop14h 09m
Deal found 8/3![Multiple Airlines logo]()
$400
This Kiwi.com deal was found by Cheapflights users on 8/3. 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.
Thu 9/175:19 pm -
1 stop20h 14m
Thu 9/247:00 am -
2 stops11h 54m
Deal found 8/3![Multiple Airlines logo]()
$437
This American Airlines deal was found by Cheapflights users on 7/31. 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.
Sat 10/247:29 am -
1 stop8h 23m
Tue 10/2712:30 pm -
1 stop12h 28m
Deal found 7/31![American Airlines logo]()
$483
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 August 4, 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 August 4, 2026.
This American Airlines deal was found by Cheapflights users on 7/30. 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 9/285:01 am -
1 stop8h 31m
Fri 10/26:30 am -
1 stop11h 18m
Deal found 7/30![American Airlines logo]()
$417
This United Airlines deal was found by Cheapflights users on 7/30. 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.
Fri 9/258:00 am -
1 stop14h 59m
Mon 9/2812:25 pm -
1 stop9h 56m
Deal found 7/30![United Airlines logo]()
$574
This Kiwi.com deal was found by Cheapflights users on 7/31. 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.
Thu 9/106:39 pm -
2 stops42h 29m
Thu 9/176:00 am -
1 stop4h 29m
Deal found 7/31![Multiple Airlines logo]()
$579
This Air Canada deal was found by Cheapflights users on 8/3. 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 Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/172:40 pm -
1 stop5h 40m
Thu 9/242:45 pm -
1 stop4h 56m
Deal found 8/3![Air Canada logo]()
$602
This Delta deal was found by Cheapflights users on 7/31. 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 10/215:31 pm -
1 stop14h 01m
Tue 10/279:30 am -
1 stop11h 44m
Deal found 7/31![Delta logo]()
$616
This American Airlines deal was found by Cheapflights users on 7/30. 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 8/176:00 am -
1 stop9h 45m
Mon 8/243:14 pm -
1 stop10h 00m
Deal found 7/30![American Airlines logo]()
$583
This United deal was found by Cheapflights users on 8/1. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/167:30 am -
1 stop14h 05m
Sun 10/1810:00 am -
1 stop5h 00m
Deal found 8/1![Multiple Airlines logo]()
$591
This United Airlines deal was found by Cheapflights users on 7/30. 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.
Fri 8/287:25 am -
1 stop5h 34m
Fri 9/46:25 am -
1 stop4h 47m
Deal found 7/30![United Airlines logo]()
$591
This Air Canada deal was found by Cheapflights users on 7/31. 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 Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/22:40 pm -
1 stop5h 40m
Sat 9/1210:00 am -
1 stop5h 00m
Deal found 7/31![Air Canada logo]()
$607
This Delta deal was found by Cheapflights users on 7/31. 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.
Fri 10/235:31 pm -
1 stop14h 01m
Tue 10/279:30 am -
1 stop11h 44m
Deal found 7/31![Delta logo]()
$633
This United deal was found by Cheapflights users on 7/30. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/2910:27 am -
1 stop8h 10m
Thu 10/112:55 pm -
Nonstop2h 05m
Deal found 7/30![Multiple Airlines logo]()
$597
This United Airlines deal was found by Cheapflights users on 7/30. 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.
Fri 9/118:30 am -
2 stops9h 29m
Tue 9/152:52 pm -
1 stop5h 19m
Deal found 7/30![United Airlines logo]()
$615
This Delta deal was found by Cheapflights users on 7/31. 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.
Fri 10/305:31 pm -
1 stop14h 01m
Mon 11/27:50 pm -
1 stop13h 39m
Deal found 7/31![Delta logo]()
$633
This United deal was found by Cheapflights users on 7/30. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/245:30 pm -
1 stop18h 05m
Mon 8/317:15 pm -
Nonstop2h 09m
Deal found 7/30![Multiple Airlines logo]()
$603
This American Airlines deal was found by Cheapflights users on 8/1. 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.
Sun 9/135:00 am -
1 stop10h 53m
Sun 9/207:50 am -
1 stop14h 53m
Deal found 8/1![American Airlines logo]()
$668
This Air Canada deal was found by Cheapflights users on 8/3. 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 Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/158:55 am -
1 stop5h 26m
Sat 9/198:40 am -
2 stops6h 20m
Deal found 8/3![Air Canada logo]()
$675
This United Airlines deal was found by Cheapflights users on 8/3. 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 9/17:25 am -
2 stops8h 13m
Mon 9/76:00 am -
1 stop4h 39m
Deal found 8/3![United Airlines logo]()
$615
This United deal was found by Cheapflights users on 7/30. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/289:04 am -
1 stop7h 52m
Fri 10/26:55 pm -
Nonstop2h 05m
Deal found 7/30![Multiple Airlines logo]()
$608
This United Airlines deal was found by Cheapflights users on 8/3. 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.
Sat 10/109:04 am -
2 stops8h 51m
Mon 10/126:25 am -
1 stop6h 48m
Deal found 8/3![United Airlines logo]()
$615
This United deal was found by Cheapflights users on 7/30. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/278:50 am -
1 stop8h 06m
Sun 8/3012:55 pm -
Nonstop2h 07m
Deal found 7/30![Multiple Airlines logo]()
$608
This United Airlines deal was found by Cheapflights users on 8/1. 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.
Fri 10/168:00 am -
1 stop4h 59m
Sun 10/186:05 am -
2 stops16h 16m
Deal found 8/1![United Airlines logo]()
$615
This United deal was found by Cheapflights users on 8/3. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/185:30 pm -
1 stop5h 29m
Tue 9/2212:55 pm -
Nonstop2h 05m
Deal found 8/3![Multiple Airlines logo]()
$611
This United Airlines deal was found by Cheapflights users on 8/3. 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.
Thu 9/178:00 am -
1 stop8h 16m
Thu 9/246:00 am -
3 stops10h 43m
Deal found 8/3![United Airlines logo]()
$616
This United deal was found by Cheapflights users on 8/3. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/56:00 am -
1 stop7h 03m
Sun 11/82:10 pm -
Nonstop2h 16m
Deal found 8/3![Multiple Airlines logo]()
$616
This United Airlines deal was found by Cheapflights users on 8/2. 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.
Sat 1/99:40 am -
1 stop10h 21m
Wed 1/136:10 am -
1 stop9h 20m
Deal found 8/2![United Airlines logo]()
$637
This United deal was found by Cheapflights users on 7/30. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/295:30 pm -
1 stop5h 29m
Sat 9/57:15 pm -
Nonstop2h 07m
Deal found 7/30![Multiple Airlines logo]()
$622
This United Airlines deal was found by Cheapflights users on 8/3. 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.
Wed 11/258:30 am -
1 stop5h 46m
Sat 11/286:00 am -
1 stop5h 32m
Deal found 8/3![United Airlines logo]()
$668
This United deal was found by Cheapflights users on 7/30. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/86:53 pm -
1 stop18h 27m
Wed 9/94:55 pm -
Nonstop2h 46m
Deal found 7/30![Multiple Airlines logo]()
$645
This United Airlines deal was found by Cheapflights users on 7/31. 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.
Thu 10/228:00 am -
2 stops10h 45m
Fri 10/307:00 am -
2 stops9h 43m
Deal found 7/31![United Airlines logo]()
$683
This United deal was found by Cheapflights users on 8/3. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/251:08 pm -
2 stops7h 34m
Sat 11/2811:10 am -
1 stop5h 16m
Deal found 8/3![Multiple Airlines logo]()
$676
Last-minute flights from St. Louis to OntarioDiscover last-minute flight deals from St. Louis to Ontario. Data last updated August 4, 2026 and is based on user searches.
Discover last-minute flight deals from St. Louis to Ontario. Data last updated August 4, 2026 and is based on user searches.
This American Airlines deal was found by Cheapflights users on 7/30. 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 8/246:00 am -
1 stop7h 33m
Mon 8/311:15 pm -
1 stop11h 59m
Deal found 7/30![American Airlines logo]()
$352
This Kiwi.com deal was found by Cheapflights users on 8/1. 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 8/316:45 pm -
1 stop10h 54m
Sun 9/67:30 am -
2 stops34h 52m
Deal found 8/1![Multiple Airlines logo]()
$424
This American Airlines deal was found by Cheapflights users on 8/1. 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 8/316:00 am -
1 stop9h 45m
Sun 9/67:20 am -
1 stop10h 00m
Deal found 8/1![American Airlines logo]()
$426
This American Airlines deal was found by Cheapflights users on 8/2. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/16:00 am -
1 stop11h 30m
Tue 9/811:39 am -
1 stop8h 48m
Deal found 8/2![American Airlines logo]()
$386
This American Airlines deal was found by Cheapflights users on 8/2. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/115:00 am -
1 stop8h 32m
Thu 9/173:13 pm -
1 stop10h 14m
Deal found 8/2![American Airlines logo]()
$369
This Kiwi.com deal was found by Cheapflights users on 8/2. 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.
Fri 9/112:29 pm -
2 stops22h 36m
Thu 9/179:50 am -
1 stop7h 34m
Deal found 8/2![Multiple Airlines logo]()
$376
This American Airlines deal was found by Cheapflights users on 8/2. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/165:00 am -
1 stop8h 32m
Wed 9/2311:40 am -
1 stop10h 04m
Deal found 8/2![American Airlines logo]()
$396
This American Airlines deal was found by Cheapflights users on 8/3. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/165:18 pm -
1 stop17h 26m
Wed 9/2312:31 pm -
1 stop12h 56m
Deal found 8/3![American Airlines logo]()
$486
This Kiwi.com deal was found by Cheapflights users on 8/3. 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.
Thu 9/175:19 pm -
1 stop20h 14m
Thu 9/247:00 am -
2 stops11h 54m
Deal found 8/3![Multiple Airlines logo]()
$437
This American Airlines deal was found by Cheapflights users on 7/30. 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 9/285:01 am -
1 stop8h 31m
Fri 10/26:30 am -
1 stop11h 18m
Deal found 7/30![American Airlines logo]()
$417
This Kiwi.com deal was found by Cheapflights users on 7/30. 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 9/282:29 pm -
2 stops25h 26m
Fri 10/29:50 am -
1 stop7h 44m
Deal found 7/30![Multiple Airlines logo]()
$430
This Kiwi.com deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/302:29 pm -
2 stops29h 26m
Mon 10/57:45 am -
1 stop9h 49m
Deal found 7/31![Multiple Airlines logo]()
$364
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 August 4, 2026.
Search for one-way flight options from St. Louis to Ontario. Find affordable one-way fares based on user searches. Data last updated August 4, 2026.
This Kiwi.com deal was found by Cheapflights users on 8/1. 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.
Thu 10/1510:35 am -
2 stops27h 20m
Deal found 8/1![Multiple Airlines logo]()
$135
This American Airlines deal was found by Cheapflights users on 7/31. 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.
Sat 8/221:25 pm -
1 stop9h 04m
Deal found 7/31![American Airlines logo]()
$147
This Kiwi.com deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/162:29 pm -
2 stops29h 26m
Deal found 7/31![Multiple Airlines logo]()
$157
This Kiwi.com deal was found by Cheapflights users on 7/30. 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 9/185:19 pm -
1 stop29h 16m
Deal found 7/30![Multiple Airlines logo]()
$162
This American Airlines deal was found by Cheapflights users on 7/31. 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 9/147:21 am -
1 stop10h 14m
Deal found 7/31![American Airlines logo]()
$168
This Kiwi.com deal was found by Cheapflights users on 7/31. 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 9/142:29 pm -
2 stops25h 16m
Deal found 7/31![Multiple Airlines logo]()
$173
This Kiwi.com deal was found by Cheapflights users on 8/3. 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.
Wed 9/92:29 pm -
2 stops29h 26m
Deal found 8/3![Multiple Airlines logo]()
$180
This Kiwi.com deal was found by Cheapflights users on 8/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/1610:35 am -
3 stops34h 29m
Deal found 8/1![Multiple Airlines logo]()
$187
This Kiwi.com deal was found by Cheapflights users on 8/4. 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 9/76:17 pm -
2 stops18h 48m
Deal found 8/4![Multiple Airlines logo]()
$198
This American Airlines deal was found by Cheapflights users on 7/30. 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.
Tue 9/155:18 pm -
1 stop17h 26m
Deal found 7/30![American Airlines logo]()
$201
This Kiwi.com deal was found by Cheapflights users on 7/31. 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 9/142:29 pm -
3 stops48h 51m
Deal found 7/31![Multiple Airlines logo]()
$206
This American Airlines deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/77:29 am -
1 stop8h 23m
Deal found 7/31![American Airlines logo]()
$213
Find flight deals from St. Louis to Ontario
Keep the following information in mind while searching for St. Louis to Ontario flight deals. Data was last updated August 4, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $344 (Kiwi.com) |
One-way from | $135 (Kiwi.com) |
Popular in | August |
Cheapest in | December |
Average price | $724 |
Good round-trip deal | $415 or less |
Good one-way deal | $275 or less |
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 August 4, 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. LouisToronto
STL - YYZ
STLYYZ
Lambert-St Louis
Mon 9/28
5:01 am-2:32 pm
1 stop8h 31m
Toronto Pearson Intl
Fri 10/2
6:30 am-4:48 pm
1 stop11h 18m
$417
St. LouisToronto
STL - YYZ
STLYYZ
Lambert-St Louis
Fri 9/25
8:00 am-11:59 pm
1 stop14h 59m
Toronto Pearson Intl
Mon 9/28
12:25 pm-9:21 pm
1 stop9h 56m
$574
St. LouisMontreal
STL - YUL
STLYUL
Lambert-St Louis
Thu 9/10
6:39 pm-2:08 pm
2 stops42h 29m
Montreal Pierre Elliott Trudeau Intl
Thu 9/17
6:00 am-9:29 am
1 stop4h 29m
$579
St. LouisToronto
STL - YYZ
STLYYZ
Lambert-St Louis
Mon 8/17
6:00 am-4:45 pm
1 stop9h 45m
Toronto Pearson Intl
Mon 8/24
3:14 pm-12:14 am
1 stop10h 00m
$583
St. LouisOttawa
STL - YOW
STLYOW
Lambert-St Louis
Fri 10/16
7:30 am-10:35 pm
1 stop14h 05m
Ottawa
Sun 10/18
10:00 am-2:00 pm
1 stop5h 00m
$591
St. LouisOttawa
STL - YOW
STLYOW
Lambert-St Louis
Fri 8/28
7:25 am-1:59 pm
1 stop5h 34m
Ottawa
Fri 9/4
6:25 am-10:12 am
1 stop4h 47m
$591
St. LouisToronto
STL - YYZ
STLYYZ
Lambert-St Louis
Tue 9/29
10:27 am-7:37 pm
1 stop8h 10m
Toronto Pearson Intl
Thu 10/1
12:55 pm-2:00 pm
Nonstop2h 05m
$597
St. LouisOttawa
STL - YOW
STLYOW
Lambert-St Louis
Thu 9/17
2:40 pm-9:20 pm
1 stop5h 40m
Ottawa
Thu 9/24
2:45 pm-6:41 pm
1 stop4h 56m
$602
St. LouisToronto
STL - YYZ
STLYYZ
Lambert-St Louis
Mon 8/24
5:30 pm-12:35 pm
1 stop18h 05m
Toronto Pearson Intl
Mon 8/31
7:15 pm-8:24 pm
Nonstop2h 09m
$603
St. LouisOttawa
STL - YOW
STLYOW
Lambert-St Louis
Wed 9/2
2:40 pm-9:20 pm
1 stop5h 40m
Ottawa
Sat 9/12
10:00 am-2:00 pm
1 stop5h 00m
$607
Showing 1-10 of 50 resultsSorted by cheapest first
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-YYZ
STL-YOW
STL-YUL
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
STL-CAON
STL-YYZ
STL-YOW
STL-YUL
What is the cheapest month to book a flight from St. Louis to Region of Ontario?
Currently, March is the cheapest month in which you can book a flight from St. Louis to Region of Ontario (average of $425). Flying from St. Louis to Region of Ontario in January is currently the most expensive (average of $840). 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.
What is the cheapest time of day to fly from STL to ON?
Find hourly flight availability from St. Louis to Ontario. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated August 4, 2026.
When flying from St. Louis to Region of Ontario, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.
How much does it cost to fly round-trip from St. Louis to Region of Ontario?
Airfare is below average for this route at the moment.
St. Louis to Region of Ontario flights typically cost between $507 and $752 in October.The cheapest round-trip price found within the last 5 days was $344 on Multiple Airlines (Oct 26-Oct 28).
How far ahead should I book a flight from St. Louis to Region of Ontario?
To ensure you get the cheapest price possible for a flight from St. Louis to Region of Ontario, you should look to book at least 88 days in advance of your intended travel date. The price of your flight may increase if you delay and leave booking until a week or so before departure.
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 August 4, 2026.
Get a feel of what it's like to fly with Delta,United Airlines, andAmerican Airlines from St. Louis to Ontario by reading reviews from past customers. You can also see how each airline compares in terms of entertainment options, comfort, food, crew/service, and boarding process.
Comfort
7.8
Entertainment
7.8
Food
7.2
Overall
7.8
Boarding
8.1
Crew
8.5
Reviews
1 / 20
10.0
ExcellentAnonymous,May 2026
SEA - KOA
Comfort
7.8
Entertainment
7.8
Food
7.2
Overall
7.8
Boarding
8.1
Crew
8.5
Reviews
1 / 20
10.0
ExcellentAnonymous,May 2026
SEA - KOA
Comfort
7.8
Entertainment
7.8
Food
7.2
Overall
7.8
Boarding
8.1
Crew
8.5
Reviews
1 / 20
10.0
ExcellentAnonymous,May 2026
SEA - KOA
Comfort
7.8
Entertainment
7.8
Food
7.2
Overall
7.8
Boarding
8.1
Crew
8.5
Reviews
1 / 20
10.0
ExcellentAnonymous,May 2026
SEA - KOA
Comfort
7.8
Entertainment
7.8
Food
7.2
Overall
7.8
Boarding
8.1
Crew
8.5
Reviews
1 / 20
10.0
ExcellentAnonymous,May 2026
SEA - KOA
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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Alternative routes for St. Louis to Ontario
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Complete your trip
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Find flights from St. Louis to Ontario, based on your preferred cabin class, be it economy, premium economy, business, or first class.
St. Louis and Ontario flights
Browse other St. Louis and Ontario flight options. Last updated on August 4, 2026.
Popular flight searches
Check out other popular destinations found by fellow travelers in 2026
Top 3 airlines flying from St. Louis to Ontario
Discover the top 3 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 August 4, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$139 | Average$535 | FlexibilityNo cancel fee | On-time67% | |
| Cheapest$203 | Average$557 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$270 | Average$545 | FlexibilityNo cancel fee | On-time71% |