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St. Louis

$163+ Cheap flights from Ontario to St. Louis (STL)

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 12/7. Fares are subject to change and may not be available on all flights or dates of travel.
YYZ — STL
Nov 29 — Dec 61
Sat 11/29
Sat 12/6
1 adult, Economy
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Find flight deals from Ontario to St. Louis

Cheapest flights from Ontario to St. Louis
Explore the most affordable flight options available from Ontario to St. Louis. Find the lowest fares from popular airlines and budget airlines, with prices last updated on October 30, 2025.

This United deal was found by Cheapflights users on 10/29. 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 12/203:10 pmYOW - STL
1 stop9h 23mMultiple Airlines
Mon 1/54:05 pmSTL - YOW
1 stop6h 03mMultiple Airlines
Deal found 10/29$307
This Kiwi.com deal was found by Cheapflights users on 10/29. 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 12/512:50 pmYYZ - STL
1 stop10h 43mMultiple Airlines
Sun 12/149:54 amSTL - YYZ
1 stop24h 49mMultiple Airlines
Deal found 10/29$319
This United Airlines deal was found by Cheapflights users on 10/29. 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 12/205:59 pmYOW - STL
1 stop6h 34mUnited Airlines
Mon 1/56:35 pmSTL - YOW
2 stops18h 55mUnited Airlines
Deal found 10/29$354
This Kiwi.com deal was found by Cheapflights users on 10/29. 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 11/104:00 pmYYZ - STL
2 stops27h 36mMultiple Airlines
Thu 11/204:13 pmSTL - YYZ
1 stop6h 58mMultiple Airlines
Deal found 10/29$362
This Kiwi.com deal was found by Cheapflights users on 10/29. 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 11/1911:15 amYYZ - STL
1 stop23h 43mMultiple Airlines
Fri 11/283:53 pmSTL - YYZ
2 stops15h 45mMultiple Airlines
Deal found 10/29$364
This Air Canada deal was found by Cheapflights users on 10/30. 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 Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/192:00 pmYYZ - STL
Nonstop2h 29mAir Canada
Sun 1/44:05 pmSTL - YYZ
Nonstop2h 01mAir Canada
Deal found 10/30$372
This Delta deal was found by Cheapflights users on 10/29. 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 11/256:05 amYYZ - STL
1 stop4h 41mDelta
Fri 11/286:40 amSTL - YYZ
1 stop3h 44mDelta
Deal found 10/29$385
This Air Canada deal was found by Cheapflights users on 10/29. 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 11/252:00 pmYYZ - STL
Nonstop2h 29mAir Canada
Fri 11/284:05 pmSTL - YYZ
Nonstop2h 01mAir Canada
Deal found 10/29$387
This Kiwi.com deal was found by Cheapflights users on 10/30. 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 11/177:55 pmYYZ - STL
2 stops14h 12mMultiple Airlines
Thu 11/2010:53 amSTL - YYZ
1 stop23h 50mMultiple Airlines
Deal found 10/30$393
This American Airlines deal was found by Cheapflights users on 10/30. 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 11/1712:34 pmYYZ - STL
1 stop9h 26mAmerican Airlines
Thu 11/205:00 amSTL - YYZ
1 stop9h 57mAmerican Airlines
Deal found 10/30$396
This American Airlines deal was found by Cheapflights users on 10/28. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/263:49 pmYUL - STL
1 stop17h 20mAmerican Airlines
Wed 12/35:05 amSTL - YUL
1 stop9h 05mAmerican Airlines
Deal found 10/28$446
This Kiwi.com deal was found by Cheapflights users on 10/28. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 11/164:35 pmYUL - STL
1 stop18h 05mMultiple Airlines
Thu 11/2710:53 amSTL - YUL
2 stops29h 02mMultiple Airlines
Deal found 10/28$450

Cheap flight deals from Ontario to St. Louis

Keep the following information in mind while searching for Ontario to St. Louis flight deals. Data was last updated October 30, 2025.

Round-trip from

$242
(Kiwi.com)

One-way from

$163
(Trip.com)

Popular in

September

Cheapest in

June

Average price

$465

Good round-trip deal

$489 or less

Good one-way deal

$323 or less
From Ontario to Lambert-St Louis
Search Deals
One-way flight from Ontario to Lambert-St Louis
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High demand for flights, 2% potential price rise
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Cheapest flight prices on average. 1% potential price decrease ($7 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in October 2025
Search Deals
Price to beat on a round-trip flight from Ontario to Lambert-St Louis.
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Price to beat on a one-way flight from Ontario to Lambert-St Louis.
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Cheapflights Fare Finder

 
Customize your flight search to find flights from Ontario to St. Louis 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 October 30, 2025.
Use the filters below to find and compare flights from Ontario to St. Louis that are best for you.

Fly from

Ontario

Fly to

St. Louis

Route

Depart

Return

Price

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Tue 4/7

6:52 am-12:20 pm

1 stop6h 28m

Lambert-St Louis

Wed 4/8

6:30 am-12:41 pm

1 stop5h 11m

$301

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Wed 1/21

11:30 am-6:14 pm

1 stop7h 44m

Lambert-St Louis

Sat 1/24

6:43 pm-10:53 am

1 stop15h 10m

$303

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Sat 12/20

3:10 pm-11:33 pm

1 stop9h 23m

Lambert-St Louis

Mon 1/5

4:05 pm-11:08 pm

1 stop6h 03m

$307

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Tue 2/24

6:00 am-1:49 pm

1 stop8h 49m

Lambert-St Louis

Sun 3/1

7:00 am-7:01 pm

1 stop11h 01m

$320

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Tue 1/13

11:30 am-6:16 pm

1 stop7h 46m

Lambert-St Louis

Fri 1/16

6:00 am-11:59 am

1 stop4h 59m

$336

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Sat 12/20

5:59 pm-11:33 pm

1 stop6h 34m

Lambert-St Louis

Mon 1/5

6:35 pm-2:30 pm

2 stops18h 55m

$354

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Tue 4/7

5:45 am-3:21 pm

2 stops10h 36m

Lambert-St Louis

Wed 4/8

4:05 pm-11:04 pm

1 stop5h 59m

$360

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Wed 1/21

5:15 pm-11:01 am

2 stops18h 46m

Lambert-St Louis

Sat 1/24

2:48 pm-11:20 pm

1 stop7h 32m

$361

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Mon 11/10

4:00 pm-6:36 pm

2 stops27h 36m

Lambert-St Louis

Thu 11/20

4:13 pm-12:11 am

1 stop6h 58m

$362

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Wed 11/19

11:15 am-9:58 am

1 stop23h 43m

Lambert-St Louis

Fri 11/28

3:53 pm-8:38 am

2 stops15h 45m

$364

Flights are sorted by cheapest round-trip flights first.

Deals found on 10/29

Showing 1-10 of 45 results
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Best time to book a flight from Ontario to St. Louis

Have a flexible travel schedule? Discover the best time to fly to St. Louis from Ontario with our price prediction graph.
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 Ontario to St. Louis

What is the cheapest month to book a flight from Region of Ontario to St. Louis?

Currently, October is the cheapest month in which you can book a flight from Region of Ontario to St. Louis (average of $300). Flying from Region of Ontario to St. Louis in January is currently the most expensive (average of $436). 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 ON to STL?

Find hourly flight availability from Ontario to St. Louis. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated October 30, 2025.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Region of Ontario to St. Louis as you normally would.

Related info for your journey

Find useful and relevant information for your journey from Ontario to St. Louis. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airport do you fly into for flights to St. Louis from Ontario?

    Located just 12.7 mi from the city center, Lambert-St Louis (STL) is the airport most travelers will use when flying to St. Louis from Ontario.

  • How long is the flight from Region of Ontario to St. Louis?

    Departing from Region of Ontario to St. Louis will take you 6h 28m. The distance between Region of Ontario and St. Louis is about 878 mi. When browsing for deals, the options you’ll see will be for both nonstop flights and flights with stops.

  • What are the most popular routes from Region of Ontario to St. Louis?

    While some choose either Montreal Pierre Elliott Trudeau Intl - Lambert-St Louis or Ottawa - Lambert-St Louis, Toronto Pearson Intl - Lambert-St Louis is the most popular route from Region of Ontario to St. Louis.

  • What are the most reliable airlines from Region of Ontario to St. Louis?

    Looking for the most reliable airlines to get you to your destination on time? Our data shows these are most likely to get you from Region of Ontario to St. Louis on time: Air Canada (82%), Jazz (82%), United Airlines (82%).

  • What are the cheapest flights from Region of Ontario to St. Louis?

    The cheapest flight price from Region of Ontario to St. Louis is $297. On average you can expect to pay $422. The most popular route, (Toronto Pearson Intl - Lambert-St Louis), can usually be booked for $263.

  • Can I find deals for flights from Ontario to St. Louis that include hotel bookings?

    Yes. In addition to deals on Ontario to St. Louis flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Ontario to St. Louis?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Ontario to St. Louis.

  • Can I find deals for business class flights from Ontario to St. Louis?

    Yes. Cheapflights offers flight deals from Ontario to St. Louis by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from Region of Ontario to St. Louis?

    Currently, October is the cheapest month in which you can book a flight from Region of Ontario to St. Louis (average of $300). Flying from Region of Ontario to St. Louis in January is currently the most expensive (average of $436). 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.

See more FAQs

Traveling to a place near St. Louis?

Book flights to St. Louis if you plan to visit one of these locations
Edwardsville
O'Fallon
Fairview Heights
Maryland Heights
Collinsville
Eureka
Glencoe
St. Peters
Chesterfield
Alton
Farmington
Festus

Browse thousands of different options on Cheapflights for your next trip

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Alternative routes for Ontario to St. Louis

See prices for flight routes from nearby airports that may be better suited for you.
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Top 2 airlines flying from Ontario to St. Louis

Discover the top 2 airlines that operate flights from Ontario to St. Louis. 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 October 30, 2025.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapest$324Average$486FlexibilityNo cancel feeOn-time67%
United AirlinesCheapest$422Average$529FlexibilityNo cancel feeOn-time69%

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