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Cheap flights from Ontario to St. Louis from C$ 267

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 8/7. Fares are subject to change and may not be available on all flights or dates of travel.
YYZ — STL
15 Jul — 22 Jul1
1 adult
1 adult, Economy, 0 bags

Cheap flight deals from Ontario to St. Louis

Enter your travel dates to find the best prices.

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 15 June 2026.

Wed 9/96:30 a.m.
YYZ
-
STL
1 stop7h 46m
American Airlines
Tue 22/97:27 a.m.
STL
-
YYZ
1 stop9h 17m
American Airlines
Deal found 13/6C$ 436
Wed 15/77:17 a.m.
YYZ
-
STL
1 stop7h 36m
American Airlines
Wed 22/76:55 a.m.
STL
-
YYZ
1 stop9h 39m
American Airlines
Deal found 14/6C$ 453
Wed 8/77:17 a.m.
YYZ
-
STL
1 stop7h 36m
American Airlines
Wed 15/76:55 a.m.
STL
-
YYZ
1 stop9h 39m
American Airlines
Deal found 13/6C$ 468
Wed 29/77:17 a.m.
YYZ
-
STL
1 stop10h 23m
American Airlines
Wed 5/86:00 a.m.
STL
-
YYZ
1 stop7h 33m
American Airlines
Deal found 14/6C$ 473
Mon 14/126:00 p.m.
YOW
-
STL
1 stop6h 25m
United Airlines
Tue 15/1210:23 a.m.
STL
-
YOW
1 stop5h 51m
United Airlines
Deal found 11/6C$ 524
Thu 9/73:10 p.m.
YOW
-
STL
1 stop4h 32m
Air Canada
Wed 15/78:55 a.m.
STL
-
YOW
1 stop5h 15m
Air Canada
Deal found 10/6C$ 527
Tue 18/82:35 p.m.
YOW
-
STL
1 stop5h 07m
Air Canada
Sat 7/114:15 p.m.
STL
-
YOW
1 stop6h 33m
Air Canada
Deal found 11/6C$ 534
Tue 18/86:05 a.m.
YOW
-
STL
2 stops10h 33m
United Airlines
Sat 7/119:23 a.m.
STL
-
YOW
1 stop11h 11m
United Airlines
Deal found 11/6C$ 536
Tue 28/79:00 a.m.
YOW
-
STL
1 stop6h 02m
Air Canada
Tue 4/812:10 p.m.
STL
-
YOW
1 stop6h 35m
Air Canada
Deal found 13/6C$ 544
Mon 20/75:50 p.m.
YOW
-
STL
1 stop6h 54m
United Airlines
Fri 24/71:13 p.m.
STL
-
YOW
1 stop7h 22m
United Airlines
Deal found 14/6C$ 545
Tue 7/75:50 p.m.
YOW
-
STL
1 stop6h 46m
United Airlines
Tue 14/76:00 a.m.
STL
-
YOW
2 stops9h 38m
United Airlines
Deal found 10/6C$ 547
Fri 3/75:50 p.m.
YOW
-
STL
1 stop6h 54m
United Airlines
Tue 7/79:20 a.m.
STL
-
YOW
1 stop6h 47m
United Airlines
Deal found 10/6C$ 550

Find 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 15 June 2026.

Round-trip from

C$ 436

One-way from

C$ 267

Popular in

March

Cheapest in

January

Average price

C$ 635

Good round-trip deal

C$ 588 or less

Good one-way deal

C$ 378 or less
American Airlines
  • American Airlines
  • 9/9-22/9
  • 2 total stops
  • 17h 03m total
  • Ontario to St. Louis
Search Deals
American Airlines
  • American Airlines
  • 8/7
  • 1 total stop
  • 11h 59m total
  • Ontario to St. Louis
Search Deals
Highest demand for flights based on searches. 21% potential increase in price (C$ 268 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 7% potential price decrease (C$ 75 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in June 2026
Search Deals
Price to beat on a round-trip flight from Ontario to Lambert-St Louis.
Search Deals
Price to beat on a one-way flight from Ontario to Lambert-St Louis.
Search Deals

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 629,999 searches. Data last updated 15 June 2026.
Use the filters below to find and compare flights from Ontario to St. Louis that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Tue 18/8

2:35 p.m.-6:42 p.m.

1 stop5h 07m

Lambert-St Louis

Sat 7/11

4:15 p.m.-11:48 p.m.

1 stop6h 33m

C$ 534

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Tue 18/8

6:05 a.m.-3:38 p.m.

2 stops10h 33m

Lambert-St Louis

Sat 7/11

9:23 a.m.-9:34 p.m.

1 stop11h 11m

C$ 536

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Mon 27/7

5:50 p.m.-11:44 p.m.

1 stop6h 54m

Lambert-St Louis

Mon 3/8

4:53 p.m.-9:11 a.m.

1 stop15h 18m

C$ 545

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Tue 28/7

6:25 a.m.-3:46 p.m.

1 stop10h 21m

Lambert-St Louis

Tue 4/8

1:13 p.m.-11:54 p.m.

2 stops9h 41m

C$ 545

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Tue 7/7

5:50 p.m.-11:36 p.m.

1 stop6h 46m

Lambert-St Louis

Tue 14/7

6:01 a.m.-4:38 p.m.

1 stop9h 37m

C$ 547

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Fri 26/6

6:25 a.m.-3:46 p.m.

1 stop10h 21m

Lambert-St Louis

Mon 29/6

9:15 a.m.-11:54 p.m.

2 stops13h 39m

C$ 547

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Tue 1/9

10:37 a.m.-3:38 p.m.

1 stop6h 01m

Lambert-St Louis

Wed 2/9

7:25 a.m.-9:35 p.m.

1 stop13h 10m

C$ 547

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Fri 3/7

6:25 a.m.-3:46 p.m.

1 stop10h 21m

Lambert-St Louis

Tue 7/7

6:00 a.m.-1:59 p.m.

1 stop6h 59m

C$ 550

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Wed 28/10

7:30 a.m.-3:38 p.m.

2 stops9h 08m

Lambert-St Louis

Mon 2/11

5:18 p.m.-12:19 a.m.

1 stop6h 01m

C$ 652

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Tue 21/7

6:30 p.m.-8:49 a.m.

1 stop15h 19m

Lambert-St Louis

Tue 28/7

1:13 p.m.-5:30 p.m.

1 stop27h 17m

C$ 671

Flights are sorted by cheapest round-trip flights first.

Deals found on 12/6

Showing 1-10 of 48 resultsSorted by cheapest first
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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, December is the cheapest month in which you can book a flight from Region of Ontario to St. Louis (average of C$ 235). Flying from Region of Ontario to St. Louis in April is currently the most expensive (average of C$ 551). 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 15 June 2026.

It’s optimal to fly from Region of Ontario to St. Louis at noon. By choosing this option you can save up to 37% on the cost of your flight, compared to a flight in the evening.

How much does it cost to fly round-trip from Region of Ontario to St. Louis?

How far ahead should I book a flight from Region of Ontario to St. Louis?

To ensure you get the cheapest price possible for a flight from Region of Ontario to St. Louis, you should look to book at least 61 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.

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?

    Most people fly into Lambert-St Louis (STL) if they book a flight to St. Louis from Ontario. Lambert-St Louis is conveniently located just 20.4 km from St. Louis’s city centre.

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

    Air Canada, United Airlines, and Delta can get you from Region of Ontario to St. Louis in just under 5h 07m. Your travel time can differ by up to 7h 16m. The distance between Region of Ontario and St. Louis is about 1413 km. When browsing for deals, the options you’ll see will be for both direct 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?

    Consider Air Canada (90%), Jazz (89%) or United Airlines (85%) when booking your flight. These represent the most reliable airlines when flying from Region of Ontario to St. Louis.

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

    Looking for the cheapest flight from Region of Ontario to St. Louis? While on average our users pay C$ 502, our data indicates the cheapest price to be C$ 304. The most popular route (Toronto Pearson Intl - Lambert-St Louis), is priced around C$ 520.

  • 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, December is the cheapest month in which you can book a flight from Region of Ontario to St. Louis (average of C$ 235). Flying from Region of Ontario to St. Louis in April is currently the most expensive (average of C$ 551). 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

Travelling to a place near St. Louis?

Book flights to St. Louis if you plan to visit one of these locations
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Top 4 airlines flying from Ontario to St. Louis

Discover the top 4 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 629,999 searches. Data last updated 15 June 2026.
AirlineCheapestAverageFlexibilityOn-time
United AirlinesCheapestC$ 342AverageC$ 669FlexibilityNo cancel feeOn-time69%
Search United Airlines flights
American AirlinesCheapestC$ 369AverageC$ 694FlexibilityNo cancel feeOn-time71%
Search American Airlines flights
Air CanadaCheapestC$ 411AverageC$ 764FlexibilityNo cancel feeOn-time67%
Search Air Canada flights
WestJetCheapestC$ 636AverageC$ 998FlexibilityNo cancel feeOn-time60%
Search WestJet flights

Fly with Cheapflights

Find the best flight deals on Cheapflights, where travelers can enjoy low prices and a wide availability of flights to their desired destinations.

How does Cheapflights help users find flights from Ontario to St. Louis?

When you search for this flight from Ontario to St. Louis, Cheapflights searches on 900+ travel sites to save you time finding great flight deals online. Additionally, we offer filter features so you can choose a preferred cabin class or airline, see different price ranges, and much more so you can book the flight for you.

Why should you use Cheapflights to find cheap flight tickets from Ontario to St. Louis?

Cheapflights helps you find that perfect flight to St. Louis from Ontario by searching from hundreds of airlines and agencies you know and love. We are also free to use, in case you were wondering!

Can Cheapflights find flights from Ontario to St. Louis with no change fees?

Certainly. Search results for flights to St. Louis from Ontario shown to you on Cheapflights can be narrowed down with different useful search filters, which includes flexible booking options.

Can Cheapflights notify me if prices for flights from Ontario to St. Louis become cheaper?

Yes! Start tracking prices for Ontario to St. Louis flights today and get alerted whenever prices for these flights change. To access this feature, click the bell icon next to the flight deals above, which will prompt you for a valid email address to receive your alerts.

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