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Cheap flights from St. Louis to Ontario from C$ 143

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 3/10. Fares are subject to change and may not be available on all flights or dates of travel.
STL — YYZ
11 Oct — 18 Oct1
1 adult
1 adult, Economy

Cheap 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 11 September 2025.

Round-trip from

C$ 362

One-way from

C$ 143

Popular in

March

Cheapest in

November

Average price

C$ 676

Good round-trip deal

C$ 841 or less

Good one-way deal

C$ 350 or less
9/10-16/10
  • 9/10-16/10
  • 3 total stops
  • 35h 08m total
  • St. Louis to Ontario
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3/10
  • 3/10
  • 2 total stops
  • 22h 17m total
  • St. Louis to Ontario
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High demand for flights, 1% potential price rise
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Cheapest flight prices on average. 3% potential price decrease (C$ 29 potential savings vs. average RT price).
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Average for round-trip flights in September 2025
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Price to beat on a round-trip flight from Lambert-St Louis to Ontario.
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Price to beat on a one-way flight from Lambert-St Louis to Ontario.
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Find flight deals from St. Louis to Ontario

Cheapest flights from St. Louis to Ontario
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 11 September 2025.

Thu 9/1010:57 a.m.STL - YYZ
1 stop11h 55mMultiple Airlines
Thu 16/101:30 p.m.YYZ - STL
2 stops23h 13mMultiple Airlines
Deal found 9/9C$ 362
Thu 30/1010:57 a.m.STL - YYZ
1 stop26h 43mMultiple Airlines
Sun 2/114:00 p.m.YYZ - STL
2 stops42h 07mMultiple Airlines
Deal found 11/9C$ 396
Thu 16/1010:57 a.m.STL - YYZ
1 stop11h 55mMultiple Airlines
Sun 19/104:00 p.m.YYZ - STL
2 stops27h 36mMultiple Airlines
Deal found 9/9C$ 428
Thu 23/1010:57 a.m.STL - YYZ
1 stop26h 08mMultiple Airlines
Sun 26/108:00 p.m.YYZ - STL
2 stops24h 26mMultiple Airlines
Deal found 11/9C$ 432
Fri 17/106:00 a.m.STL - YYZ
1 stop10h 40mAmerican Airlines
Tue 21/1011:44 a.m.YYZ - STL
1 stop9h 42mAmerican Airlines
Deal found 9/9C$ 457
Thu 9/1010:57 a.m.STL - YYZ
1 stop11h 55mMultiple Airlines
Mon 13/104:00 p.m.YYZ - STL
2 stops42h 07mMultiple Airlines
Deal found 11/9C$ 459
Wed 24/97:55 p.m.STL - YYZ
2 stops23h 03mMultiple Airlines
Sat 4/109:35 a.m.YYZ - STL
1 stop25h 27mMultiple Airlines
Deal found 10/9C$ 467
Fri 17/106:00 a.m.STL - YYZ
1 stop10h 40mAmerican Airlines
Thu 30/106:30 a.m.YYZ - STL
1 stop10h 34mAmerican Airlines
Deal found 9/9C$ 479
Fri 3/109:32 p.m.STL - YYZ
1 stop15h 20mMultiple Airlines
Mon 6/104:00 p.m.YYZ - STL
2 stops27h 36mMultiple Airlines
Deal found 9/9C$ 482
Thu 23/1010:57 a.m.STL - YYZ
1 stop8h 58mMultiple Airlines
Sat 25/102:50 p.m.YYZ - STL
2 stops19h 32mMultiple Airlines
Deal found 10/9C$ 484
Sat 25/104:34 p.m.STL - YUL
1 stop18h 06mAmerican Airlines
Sat 1/1112:30 p.m.YUL - STL
1 stop10h 38mAmerican Airlines
Deal found 10/9C$ 522
Fri 5/129:45 a.m.STL - YUL
2 stops11h 25mMultiple Airlines
Mon 8/124:35 p.m.YUL - STL
1 stop31h 11mMultiple Airlines
Deal found 10/9C$ 567

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 629,999 searches. Data last updated 11 September 2025.
Use the filters below to find and compare flights from St. Louis to Ontario that are best for you.

Fly from

St. Louis

Fly to

Ontario

Route

Depart

Return

Price

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Thu 23/10

10:57 a.m.-2:05 p.m.

1 stop26h 08m

Toronto Pearson Intl

Sun 26/10

8:00 p.m.-7:26 p.m.

2 stops24h 26m

C$ 432

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Fri 17/10

6:00 a.m.-5:40 p.m.

1 stop10h 40m

Toronto Pearson Intl

Tue 21/10

11:44 a.m.-8:26 p.m.

1 stop9h 42m

C$ 457

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Sat 25/10

4:34 p.m.-11:40 a.m.

1 stop18h 06m

Montreal Pierre Elliott Trudeau Intl

Sat 1/11

12:30 p.m.-10:08 p.m.

1 stop10h 38m

C$ 522

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Thu 9/10

10:57 a.m.-11:52 p.m.

1 stop11h 55m

Toronto Pearson Intl

Sat 11/10

6:30 a.m.-6:10 p.m.

1 stop12h 40m

C$ 567

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Fri 5/12

9:45 a.m.-10:10 p.m.

2 stops11h 25m

Montreal Pierre Elliott Trudeau Intl

Mon 8/12

4:35 p.m.-10:46 p.m.

1 stop31h 11m

C$ 567

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Thu 23/10

9:50 a.m.-9:07 p.m.

2 stops10h 17m

Toronto Pearson Intl

Sat 25/10

12:00 p.m.-10:02 a.m.

3 stops23h 02m

C$ 572

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Fri 17/10

8:05 p.m.-11:40 a.m.

1 stop14h 35m

Montreal Pierre Elliott Trudeau Intl

Mon 20/10

5:24 p.m.-8:09 a.m.

1 stop15h 45m

C$ 593

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Fri 3/10

9:32 p.m.-2:20 p.m.

1 stop15h 48m

Montreal Pierre Elliott Trudeau Intl

Sat 11/10

7:20 p.m.-10:37 a.m.

2 stops16h 17m

C$ 594

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Thu 9/10

10:57 a.m.-10:40 p.m.

2 stops10h 43m

Toronto Pearson Intl

Thu 16/10

6:30 a.m.-12:00 p.m.

3 stops30h 30m

C$ 612

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Sun 9/11

2:12 p.m.-12:30 a.m.

1 stop9h 18m

Montreal Pierre Elliott Trudeau Intl

Wed 12/11

6:45 a.m.-11:01 a.m.

1 stop29h 16m

C$ 632

Flights are sorted by cheapest round-trip flights first.

Deals found on 9/9

Showing 1-10 of 37 results
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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.
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

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

Currently, January is the cheapest month in which you can book a flight from St. Louis to Region of Ontario (average of C$ 168). Flying from St. Louis to Region of Ontario in July is currently the most expensive (average of C$ 258). 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 11 September 2025.

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.

Weekly flight availability from St. Louis to Region of Ontario

Explore weekly flight availability from St. Louis to Ontario. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated 11 September 2025.

The most flights from STL to CAON are scheduled on a Monday (5 on average). You will have fewer flight options on Monday, which is when the least amount of flights are scheduled (5 on average).

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 11 September 2025.
See what other customers who have flown with Air Canada from St. Louis to Ontario have to say. Users can see the overall rating for each airline as well as how each is rated in terms of entertainment options, comfort, food, crew/service, and boarding process.
Air Canada
7.1
Good
10,000 reviews
Check prices

Boarding

7.3

Entertainment

6.8

Comfort

7.1

Food

6.3

Crew

7.8

Overall

7.1

Reviews

1 / 20
10.0
Excellent

janet,Sep 2025

YOW - YYZ

Really appreciated the leg room despite purchasing an economy ticket. Appreciated the extra complimentary wine. Nice touch. Was given immediate support without asking at check in, at the machine!! Ottawa's boarding was very organized with distinct rows in waiting room. Allowed for the main hall to not be blocked by people waiting to board.
Air Canada
7.1
Good
10,000 reviews
Air Canada
7.1
Good
10,000 reviews
Check prices

Boarding

7.3

Entertainment

6.8

Comfort

7.1

Food

6.3

Crew

7.8

Overall

7.1

Reviews

1 / 20
10.0
Excellent

janet,Sep 2025

YOW - YYZ

Really appreciated the leg room despite purchasing an economy ticket. Appreciated the extra complimentary wine. Nice touch. Was given immediate support without asking at check in, at the machine!! Ottawa's boarding was very organized with distinct rows in waiting room. Allowed for the main hall to not be blocked by people waiting to board.

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.

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

    If you book a flight to Ontario from St. Louis, you will be flying from Lambert-St Louis, which is the city’s only airport. Lambert-St Louis (STL) is located 20.4 km from the centre of St. Louis.

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

    Departing from St. Louis to Region of Ontario will take you 4h 16m. St. Louis and Region of Ontario are separated by a distance of 908 km. Both multi-stop and direct flights can be found to your destination and back.

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

    The most popular flight routes from St. Louis to Region of Ontario are Lambert-St Louis - Toronto Pearson Intl, Lambert-St Louis - Montreal Pierre Elliott Trudeau Intl and Lambert-St Louis - London.

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

    Before booking your flight to Region of Ontario from St. Louis, check out the most reliable airlines to get you to your destination on time: Air Canada (86%), Jazz (86%), United Airlines( 57%).

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

    The cheapest flight price from St. Louis to Region of Ontario is C$ 350. On average you can expect to pay C$ 827. The most popular route, (Lambert-St Louis - Toronto Pearson Intl), can usually be booked for C$ 362.

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

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

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

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

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

    Yes. Cheapflights offers flight deals from St. Louis to Ontario 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 St. Louis to Region of Ontario?

    Currently, January is the cheapest month in which you can book a flight from St. Louis to Region of Ontario (average of C$ 168). Flying from St. Louis to Region of Ontario in July is currently the most expensive (average of C$ 258). 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

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Alternative routes for St. Louis to Ontario

See prices for flight routes from nearby airports that may be better suited for you.
St. Louis to Pearson Intl flights
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Top airline flying from St. Louis to Ontario

Discover the top airline 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 629,999 searches. Data last updated 11 September 2025.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapestC$ 302AverageC$ 672FlexibilityNo cancel feeOn-time67%
Search Air Canada 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 St. Louis to Ontario?

Cheapflights helps you search for flights from St. Louis to Ontario via 900+ travel sites so you don’t have to. After performing a flight search, users can also filter their flight selection by filtering for price, number of stops, airlines, and so on.

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

By finding flights from multiple airlines and providers at completely no cost, Cheapflights helps millions of users like you annually find the best flights to Ontario from St. Louis.

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

Certainly. Search results for flights to Ontario from St. Louis 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 St. Louis to Ontario become cheaper?

Yes! Start tracking prices for St. Louis to Ontario 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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