Find flights
Deals
When to book
FAQs

Cheap flights from Ontario to St. Louis from C$ 204

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 26/2. Fares are subject to change and may not be available on all flights or dates of travel.
YYZ — STL
29 Nov — 6 Dec1
1 adult
1 adult, Economy, 0 bags

Find 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 30 October 2025.

Tue 9/1211:36 a.m.YYZ - STL
1 stop9h 48mAmerican Airlines
Wed 10/125:05 a.m.STL - YYZ
1 stop9h 58mAmerican Airlines
Deal found 27/10C$ 427
Sat 20/123:10 p.m.YOW - STL
1 stop9h 23mMultiple Airlines
Mon 5/14:05 p.m.STL - YOW
1 stop6h 03mMultiple Airlines
Deal found 29/10C$ 429
Fri 5/1212:50 p.m.YYZ - STL
1 stop10h 43mMultiple Airlines
Sun 14/129:54 a.m.STL - YYZ
1 stop24h 49mMultiple Airlines
Deal found 29/10C$ 445
Fri 5/126:00 a.m.YYZ - STL
1 stop8h 14mAmerican Airlines
Mon 8/125:15 a.m.STL - YYZ
1 stop9h 48mAmerican Airlines
Deal found 28/10C$ 447
Fri 26/121:14 p.m.YYZ - STL
1 stop11h 41mAmerican Airlines
Thu 8/16:00 a.m.STL - YYZ
1 stop9h 03mAmerican Airlines
Deal found 28/10C$ 462
Sat 20/125:59 p.m.YOW - STL
1 stop6h 34mUnited Airlines
Mon 5/16:35 p.m.STL - YOW
2 stops18h 55mUnited Airlines
Deal found 29/10C$ 494
Mon 10/114:00 p.m.YYZ - STL
2 stops27h 36mMultiple Airlines
Thu 20/114:13 p.m.STL - YYZ
1 stop6h 58mMultiple Airlines
Deal found 29/10C$ 505
Fri 21/112:00 p.m.YYZ - STL
Nonstop2h 29mAir Canada
Mon 24/114:05 p.m.STL - YYZ
Nonstop2h 01mAir Canada
Deal found 28/10C$ 507
Wed 19/1111:15 a.m.YYZ - STL
1 stop23h 43mMultiple Airlines
Fri 28/113:53 p.m.STL - YYZ
2 stops15h 45mMultiple Airlines
Deal found 29/10C$ 508
Fri 21/114:10 p.m.YYZ - STL
1 stop6h 44mMultiple Airlines
Mon 24/114:05 p.m.STL - YYZ
Nonstop2h 01mMultiple Airlines
Deal found 28/10C$ 528
Tue 25/112:00 p.m.YYZ - STL
Nonstop2h 29mAir Canada
Fri 28/114:05 p.m.STL - YYZ
Nonstop2h 01mAir Canada
Deal found 28/10C$ 529
Tue 25/1112:08 p.m.YYZ - STL
1 stop6h 01mDelta
Fri 28/116:40 a.m.STL - YYZ
1 stop3h 44mDelta
Deal found 28/10C$ 538

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 30 October 2025.

Round-trip from

C$ 413

One-way from

C$ 204

Popular in

September

Cheapest in

June

Average price

C$ 649

Good round-trip deal

C$ 592 or less
Air Canada
  • Air Canada
  • 3/2-4/2
  • 2 total stops
  • 13h 17m total
  • Ontario to St. Louis
Search Deals
26/2
  • 26/2
  • 1 total stop
  • 16h 23m total
  • Ontario to St. Louis
Search Deals
High demand for flights, 2% potential price rise
Search Deals
Cheapest flight prices on average. 1% potential price decrease (C$ 14 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.
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 30 October 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 3/2

9:15 a.m.-3:29 p.m.

1 stop7h 14m

Lambert-St Louis

Wed 4/2

4:05 p.m.-11:08 p.m.

1 stop6h 03m

C$ 413

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Tue 7/4

6:52 a.m.-12:20 p.m.

1 stop6h 28m

Lambert-St Louis

Wed 8/4

6:30 a.m.-12:41 p.m.

1 stop5h 11m

C$ 420

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Wed 21/1

11:30 a.m.-6:14 p.m.

1 stop7h 44m

Lambert-St Louis

Sat 24/1

6:43 p.m.-10:53 a.m.

1 stop15h 10m

C$ 423

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Sat 20/12

3:10 p.m.-11:33 p.m.

1 stop9h 23m

Lambert-St Louis

Mon 5/1

4:05 p.m.-11:08 p.m.

1 stop6h 03m

C$ 429

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Tue 24/2

6:00 a.m.-1:49 p.m.

1 stop8h 49m

Lambert-St Louis

Sun 1/3

7:00 a.m.-7:01 p.m.

1 stop11h 01m

C$ 447

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Fri 26/12

1:14 p.m.-11:55 p.m.

1 stop11h 41m

Lambert-St Louis

Thu 8/1

6:00 a.m.-4:03 p.m.

1 stop9h 03m

C$ 462

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Tue 13/1

11:30 a.m.-6:16 p.m.

1 stop7h 46m

Lambert-St Louis

Fri 16/1

6:00 a.m.-11:59 a.m.

1 stop4h 59m

C$ 469

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Sat 20/12

5:59 p.m.-11:33 p.m.

1 stop6h 34m

Lambert-St Louis

Mon 5/1

6:35 p.m.-2:30 p.m.

2 stops18h 55m

C$ 494

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Tue 7/4

5:45 a.m.-3:21 p.m.

2 stops10h 36m

Lambert-St Louis

Wed 8/4

4:05 p.m.-11:04 p.m.

1 stop5h 59m

C$ 503

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Wed 21/1

5:15 p.m.-11:01 a.m.

2 stops18h 46m

Lambert-St Louis

Sat 24/1

2:48 p.m.-11:20 p.m.

1 stop7h 32m

C$ 504

Flights are sorted by cheapest round-trip flights first.

Deals found on 28/10

Showing 1-10 of 45 results
1
2
3
...
5

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 C$ 419). Flying from Region of Ontario to St. Louis in January is currently the most expensive (average of C$ 609). 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 30 October 2025.

It’s optimal to fly from Region of Ontario to St. Louis in the afternoon. By choosing this option you can save up to 30% on the cost of your flight, compared to a flight in the morning.

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 American Airlines can get you from Region of Ontario to St. Louis in just under 6h 28m. Your travel time can differ by up to 1h 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 (82%), Jazz (82%) or United Airlines (82%) 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$ 600, our data indicates the cheapest price to be C$ 501. The most popular route (Toronto Pearson Intl - Lambert-St Louis), is priced around C$ 367.

  • 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 C$ 419). Flying from Region of Ontario to St. Louis in January is currently the most expensive (average of C$ 609). 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
Chesterfield
St. Peters

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for Ontario to St. Louis

See prices for flight routes from nearby airports that may be better suited for you.
Pearson Intl to St. Louis flights
Pearson Intl to Kansas City flights
Calgary to Kansas City flights
Edmonton to St. Louis flights
Pierre Elliott Trudeau Intl to St. Louis flights
Vancouver Intl to Kansas City flights
Vancouver Intl to St. Louis flights
Pierre Elliott Trudeau Intl to Kansas City flights
Edmonton to Kansas City flights
Abbotsford to Kansas City flights
Vancouver Intl to Springfield flights
Ottawa to St. Louis flights
Ottawa to Kansas City flights
Calgary to St. Louis flights
Winnipeg to Kansas City flights
Pearson Intl to Springfield flights
Halifax to St. Louis flights
Pearson Intl to Columbia flights
Victoria to St. Louis flights
Québec City to St. Louis flights
Saskatoon to Kansas City flights
Victoria to Kansas City flights
Comox to Kansas City flights
Halifax to Kansas City flights
Charlottetown to St. Louis flights
Pearson Intl to Quincy flights
Saskatoon to St. Louis flights
Calgary to Columbia flights
Edmonton to Columbia flights
Pierre Elliott Trudeau Intl to Cape Girardeau flights
Regina to Branson flights

Top 5 airlines flying from Ontario to St. Louis

Discover the top 5 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 30 October 2025.
AirlineCheapestAverageFlexibilityOn-time
American AirlinesCheapestC$ 435AverageC$ 693FlexibilityNo cancel feeOn-time71%
Search American Airlines flights
United AirlinesCheapestC$ 470AverageC$ 769FlexibilityNo cancel feeOn-time69%
Search United Airlines flights
Air CanadaCheapestC$ 475AverageC$ 764FlexibilityNo cancel feeOn-time67%
Search Air Canada flights
DeltaCheapestC$ 480AverageC$ 661FlexibilityNo cancel feeOn-timeN/A
Search Delta flights
WestJetCheapestC$ 563AverageC$ 890FlexibilityNo 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.

100% Free

Cheapflights is completely free to use, so you can start saving the moment you arrive.

Book with Flexibility

Our users can plan ahead with confidence and find flights with no change fees

Travel Smart

Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.