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Cheap flights from St. Louis to Ontario from C$ 154

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 4/12. Fares are subject to change and may not be available on all flights or dates of travel.
STL — YYZ
29 Nov — 6 Dec1
1 adult
1 adult, Economy, 0 bags

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 30 October 2025.

Round-trip from

C$ 377

One-way from

C$ 154

Popular in

March

Cheapest in

January

Average price

C$ 760

Good round-trip deal

C$ 345 or less
8/1-14/1
  • 8/1-14/1
  • 2 total stops
  • 36h 31m total
  • St. Louis to Ontario
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American Airlines
  • American Airlines
  • 4/12
  • 1 total stop
  • 9h 48m total
  • St. Louis to Ontario
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High demand for flights, 9% potential price rise
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Cheapest flight prices on average. 2% potential price decrease (C$ 25 potential savings vs. average RT price).
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Average for round-trip flights in October 2025
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Price to beat on a round-trip flight from Lambert-St Louis to Ontario.
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Find flight deals from St. Louis to Ontario

Enter your travel dates to find the best prices.

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 30 October 2025.

Thu 4/123:30 p.m.STL - YYZ
1 stop7h 41mMultiple Airlines
Mon 8/1212:50 p.m.YYZ - STL
1 stop10h 43mMultiple Airlines
Deal found 28/10C$ 420
Mon 17/119:50 a.m.STL - YYZ
2 stops10h 17mMultiple Airlines
Fri 21/117:00 a.m.YYZ - STL
1 stop26h 57mMultiple Airlines
Deal found 28/10C$ 441
Mon 8/1210:47 a.m.STL - YYZ
2 stops12h 38mMultiple Airlines
Mon 15/127:15 a.m.YYZ - STL
1 stop16h 18mMultiple Airlines
Deal found 30/10C$ 448
Mon 17/119:50 a.m.STL - YYZ
2 stops10h 17mMultiple Airlines
Thu 20/115:15 p.m.YYZ - STL
1 stop7h 42mMultiple Airlines
Deal found 28/10C$ 500
Sun 16/116:21 p.m.STL - YYZ
2 stops25h 46mMultiple Airlines
Thu 20/115:15 p.m.YYZ - STL
1 stop7h 42mMultiple Airlines
Deal found 28/10C$ 505
Sun 7/123:30 p.m.STL - YYZ
1 stop19h 13mMultiple Airlines
Thu 11/127:55 p.m.YYZ - STL
1 stop17h 17mMultiple Airlines
Deal found 29/10C$ 512
Mon 1/124:13 p.m.STL - YYZ
1 stop6h 58mMultiple Airlines
Thu 4/129:35 a.m.YYZ - STL
1 stop27h 37mMultiple Airlines
Deal found 29/10C$ 518
Fri 28/113:53 p.m.STL - YYZ
2 stops15h 45mMultiple Airlines
Mon 1/125:15 p.m.YYZ - STL
1 stop30h 18mMultiple Airlines
Deal found 29/10C$ 525
Thu 11/128:38 a.m.STL - YYZ
1 stop8h 06mAmerican Airlines
Sun 14/126:00 a.m.YYZ - STL
1 stop9h 50mAmerican Airlines
Deal found 29/10C$ 529
Mon 15/123:30 p.m.STL - YUL
2 stops27h 14mMultiple Airlines
Mon 22/128:00 a.m.YUL - STL
1 stop27h 56mMultiple Airlines
Deal found 30/10C$ 673
Wed 3/125:05 a.m.STL - YUL
1 stop9h 05mAmerican Airlines
Sun 7/123:50 p.m.YUL - STL
1 stop17h 18mAmerican Airlines
Deal found 30/10C$ 681
Mon 15/125:15 a.m.STL - YUL
2 stops16h 25mAmerican Airlines
Tue 6/13:52 p.m.YUL - STL
1 stop19h 29mAmerican Airlines
Deal found 30/10C$ 705

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 30 October 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 8/1

5:11 p.m.-2:20 p.m.

1 stop20h 09m

Toronto Pearson Intl

Wed 14/1

7:15 a.m.-10:37 p.m.

1 stop16h 22m

C$ 377

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Sat 14/2

6:33 p.m.-3:05 p.m.

1 stop19h 32m

Montreal Pierre Elliott Trudeau Intl

Wed 18/2

3:55 p.m.-9:33 a.m.

1 stop18h 38m

C$ 406

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sat 14/2

10:03 a.m.-9:29 p.m.

1 stop10h 26m

Toronto Pearson Intl

Sat 21/2

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

1 stop8h 49m

C$ 419

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Thu 4/12

3:30 p.m.-12:11 a.m.

1 stop7h 41m

Toronto Pearson Intl

Mon 8/12

12:50 p.m.-10:33 p.m.

1 stop10h 43m

C$ 420

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Mon 17/11

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

2 stops10h 17m

Toronto Pearson Intl

Fri 21/11

7:00 a.m.-8:57 a.m.

1 stop26h 57m

C$ 441

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sat 28/2

5:11 p.m.-2:20 p.m.

1 stop20h 09m

Toronto Pearson Intl

Wed 4/3

6:30 p.m.-9:47 a.m.

2 stops16h 17m

C$ 494

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Fri 28/11

3:53 p.m.-8:38 a.m.

2 stops15h 45m

Toronto Pearson Intl

Mon 1/12

5:15 p.m.-10:33 p.m.

1 stop30h 18m

C$ 525

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Fri 16/1

6:52 a.m.-5:40 p.m.

1 stop9h 48m

Toronto Pearson Intl

Sun 18/1

7:00 p.m.-10:21 a.m.

1 stop16h 21m

C$ 529

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Tue 17/2

7:41 a.m.-9:17 p.m.

1 stop12h 36m

Montreal Pierre Elliott Trudeau Intl

Thu 19/2

1:10 p.m.-10:59 p.m.

1 stop10h 49m

C$ 539

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Fri 16/1

11:05 a.m.-9:23 p.m.

1 stop9h 18m

Toronto Pearson Intl

Mon 19/1

6:00 a.m.-1:03 p.m.

1 stop8h 03m

C$ 539

Flights are sorted by cheapest round-trip flights first.

Deals found on 29/10

Showing 1-10 of 31 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, June is the cheapest month in which you can book a flight from St. Louis to Region of Ontario (average of C$ 250). Flying from St. Louis to Region of Ontario in February is currently the most expensive (average of C$ 504). 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 30 October 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.

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

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 30 October 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
10,381 reviews
Check prices

Comfort

7.1

Entertainment

6.8

Crew

7.8

Overall

7.1

Boarding

7.3

Food

6.3

Reviews

1 / 20
2.0
Mediocre

Shawna,Sep 2025

DCA - YYZ

Business class cabin was *freezing*. Landing was so hard it injured my back - no apology or explanation given
Air Canada
7.1
Good
10,381 reviews
Air Canada
7.1
Good
10,381 reviews
Check prices

Comfort

7.1

Entertainment

6.8

Crew

7.8

Overall

7.1

Boarding

7.3

Food

6.3

Reviews

1 / 20
2.0
Mediocre

Shawna,Sep 2025

DCA - YYZ

Business class cabin was *freezing*. Landing was so hard it injured my back - no apology or explanation given

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 12h 36m. St. Louis and Region of Ontario are separated by a distance of 1556 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 (93%), Jazz (93%), United Airlines( 93%).

  • 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$ 244. On average you can expect to pay C$ 473. The most popular route, (Lambert-St Louis - Toronto Pearson Intl), can usually be booked for C$ 415.

  • 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, June is the cheapest month in which you can book a flight from St. Louis to Region of Ontario (average of C$ 250). Flying from St. Louis to Region of Ontario in February is currently the most expensive (average of C$ 504). 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
Kansas City to Pearson Intl flights
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Kansas City to Vancouver Intl flights
Kansas City to Pierre Elliott Trudeau Intl flights
St. Louis to Calgary flights
Kansas City to Québec City flights
Kansas City to Halifax flights
Kansas City to Calgary flights
St. Louis to Québec City flights
St. Louis to Winnipeg flights
St. Louis to Halifax flights
St. Louis to Saskatoon flights
St. Louis to Edmonton flights
Kansas City to Ottawa flights
Kansas City to Moncton flights
Springfield to Pearson Intl flights
St. Louis to Charlottetown flights
Kansas City to Victoria flights
Joplin to Pierre Elliott Trudeau Intl flights
Kansas City to Saskatoon flights
St. Louis to Kelowna flights

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 30 October 2025.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapestC$ 304AverageC$ 651FlexibilityNo 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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