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Cheap flights from Ontario to St. Louis from C$ 241

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 25/10. Fares are subject to change and may not be available on all flights or dates of travel.
YYZ — STL
5 Aug — 12 Aug1
1 adult

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 31 July 2025.

Round-trip from

C$ 450

One-way from

C$ 241

Popular in

August

Cheapest in

June

Average price

C$ 682

Good round-trip deal

C$ 537 or less

Good one-way deal

C$ 486 or less
American Airlines
  • American Airlines
  • 21/10-27/10
  • 2 total stops
  • 17h 35m total
  • Ontario to St. Louis
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25/10
  • 25/10
  • 1 total stop
  • 12h 25m total
  • Ontario to St. Louis
Search Deals
Highest demand for flights based on searches. 4% potential increase in price (C$ 46 potential increase over avg. RT price).
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Cheapest flight prices on average. 1% potential price decrease (C$ 16 potential savings vs. average RT price).
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Average for round-trip flights in July 2025
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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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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 31 July 2025.

Sat 8/114:44 p.m.YYZ - STL
1 stop8h 12mAmerican Airlines
Sat 15/116:00 a.m.STL - YYZ
1 stop9h 04mAmerican Airlines
Deal found 29/7C$ 444
Sat 13/912:31 p.m.YUL - STL
1 stop10h 22mAmerican Airlines
Sat 20/92:01 p.m.STL - YUL
1 stop20h 45mAmerican Airlines
Deal found 30/7C$ 451
Sat 8/112:00 p.m.YYZ - STL
Nonstop2h 29mAir Canada
Sat 15/114:05 p.m.STL - YYZ
Nonstop2h 01mAir Canada
Deal found 29/7C$ 511
Mon 24/113:30 p.m.YYZ - STL
1 stop8h 15mUnited Airlines
Fri 28/116:30 a.m.STL - YYZ
1 stop8h 31mUnited Airlines
Deal found 31/7C$ 554
Mon 8/96:00 a.m.YUL - STL
1 stop27h 06mDelta
Tue 16/96:40 a.m.STL - YUL
1 stop4h 20mDelta
Deal found 29/7C$ 565
Mon 8/96:10 p.m.YUL - STL
Nonstop2h 47mAir Canada
Tue 16/99:15 a.m.STL - YUL
1 stop6h 05mAir Canada
Deal found 29/7C$ 591
Sun 7/96:45 a.m.YYZ - STL
2 stops18h 14mMultiple Airlines
Thu 11/910:35 a.m.STL - YYZ
1 stop9h 20mMultiple Airlines
Deal found 30/7C$ 596
Wed 27/86:15 a.m.YUL - STL
1 stop10h 29mUnited Airlines
Wed 3/97:04 p.m.STL - YUL
1 stop14h 36mUnited Airlines
Deal found 30/7C$ 616
Fri 12/97:00 a.m.YUL - STL
3 stops10h 35mMultiple Airlines
Fri 19/91:00 p.m.STL - YUL
3 stops25h 20mMultiple Airlines
Deal found 29/7C$ 666
Wed 20/86:49 p.m.YYZ - STL
1 stop14h 17mDelta
Wed 10/912:29 p.m.STL - YYZ
1 stop10h 18mDelta
Deal found 31/7C$ 668
Tue 9/98:00 p.m.YYZ - STL
2 stops14h 15mWestJet
Thu 11/96:40 a.m.STL - YYZ
1 stop9h 43mWestJet
Deal found 31/7C$ 677
Mon 22/125:09 p.m.YOW - STL
1 stop6h 34mUnited Airlines
Mon 5/111:05 a.m.STL - YOW
1 stop9h 13mUnited Airlines
Deal found 30/7C$ 864

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 31 July 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

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Tue 21/10

1:15 p.m.-8:26 p.m.

1 stop8h 11m

Lambert-St Louis

Mon 27/10

7:16 a.m.-5:40 p.m.

1 stop9h 24m

C$ 450

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Sat 13/9

12:31 p.m.-9:53 p.m.

1 stop10h 22m

Lambert-St Louis

Sat 20/9

2:01 p.m.-11:46 a.m.

1 stop20h 45m

C$ 451

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Wed 27/8

3:00 p.m.-8:00 p.m.

1 stop6h 00m

Lambert-St Louis

Wed 3/9

9:15 a.m.-12:11 p.m.

Nonstop1h 56m

C$ 545

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Mon 8/9

6:00 a.m.-8:06 a.m.

1 stop27h 06m

Lambert-St Louis

Tue 16/9

6:40 a.m.-12:00 p.m.

1 stop4h 20m

C$ 565

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Mon 8/9

6:10 p.m.-7:57 p.m.

Nonstop2h 47m

Lambert-St Louis

Tue 16/9

9:15 a.m.-4:20 p.m.

1 stop6h 05m

C$ 591

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Sun 7/9

6:45 a.m.-11:59 p.m.

2 stops18h 14m

Lambert-St Louis

Thu 11/9

10:35 a.m.-8:55 p.m.

1 stop9h 20m

C$ 596

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Wed 27/8

6:15 a.m.-3:44 p.m.

1 stop10h 29m

Lambert-St Louis

Wed 3/9

7:04 p.m.-10:40 a.m.

1 stop14h 36m

C$ 616

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Tue 21/10

2:30 p.m.-10:35 p.m.

2 stops9h 05m

Lambert-St Louis

Mon 27/10

3:14 p.m.-11:46 p.m.

2 stops7h 32m

C$ 632

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Fri 12/9

7:00 a.m.-4:35 p.m.

3 stops10h 35m

Lambert-St Louis

Fri 19/9

1:00 p.m.-3:20 p.m.

3 stops25h 20m

C$ 666

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Wed 20/8

6:49 p.m.-8:06 a.m.

1 stop14h 17m

Lambert-St Louis

Wed 10/9

12:29 p.m.-11:47 p.m.

1 stop10h 18m

C$ 668

Flights are sorted by cheapest round-trip flights first.

Deals found on 30/7

Showing 1-10 of 30 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, January is the cheapest month in which you can book a flight from Region of Ontario to St. Louis (average of C$ 365). Flying from Region of Ontario to St. Louis in September is currently the most expensive (average of C$ 491). 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 31 July 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.

Weekly flight availability from Region of Ontario to St. Louis

Explore weekly flight availability from Ontario to St. Louis. 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 31 July 2025.

The most flights from CAON to STL are scheduled on a Wednesday (4 on average). You will have fewer flight options on Monday, which is when the least amount of flights are scheduled (2 on average).

Reviews of airlines servicing St. Louis

Get insights into the airlines that provide service to St. Louis. 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 St. Louis. Reviews last updated 31 July 2025.
Read through reviews of airlines operating flights from Ontario to St. Louis, such as Delta,United Airlines, andAmerican Airlines. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Delta
8.0
Very good
7,981 reviews
Check prices

Comfort

7.9

Crew

8.5

Food

7.3

Overall

8.0

Boarding

8.2

Entertainment

7.9

Reviews

1 / 20
8.0
Excellent

Michael,Jul 2025

AMS - ATL

Overall it was great experience, with the exception of snack food. The food offered in two main meals was just fine but for the mid-flight snack, the only option was a large cookie, too sweet and high sugar content. Snacks at the back of the plane were also mainly sweets. There was one nice baked cheddar option but it quickly ran out.
Delta
8.0
Very good
7,981 reviews
Delta
8.0
Very good
7,981 reviews
Check prices

Comfort

7.9

Crew

8.5

Food

7.3

Overall

8.0

Boarding

8.2

Entertainment

7.9

Reviews

1 / 20
8.0
Excellent

Michael,Jul 2025

AMS - ATL

Overall it was great experience, with the exception of snack food. The food offered in two main meals was just fine but for the mid-flight snack, the only option was a large cookie, too sweet and high sugar content. Snacks at the back of the plane were also mainly sweets. There was one nice baked cheddar option but it quickly ran out.
United Airlines
7.4
Good
8,900 reviews
Delta
8.0
Very good
7,981 reviews
Check prices

Comfort

7.9

Crew

8.5

Food

7.3

Overall

8.0

Boarding

8.2

Entertainment

7.9

Reviews

1 / 20
8.0
Excellent

Michael,Jul 2025

AMS - ATL

Overall it was great experience, with the exception of snack food. The food offered in two main meals was just fine but for the mid-flight snack, the only option was a large cookie, too sweet and high sugar content. Snacks at the back of the plane were also mainly sweets. There was one nice baked cheddar option but it quickly ran out.
American Airlines
7.2
Good
10,000 reviews
Delta
8.0
Very good
7,981 reviews
Check prices

Comfort

7.9

Crew

8.5

Food

7.3

Overall

8.0

Boarding

8.2

Entertainment

7.9

Reviews

1 / 20
8.0
Excellent

Michael,Jul 2025

AMS - ATL

Overall it was great experience, with the exception of snack food. The food offered in two main meals was just fine but for the mid-flight snack, the only option was a large cookie, too sweet and high sugar content. Snacks at the back of the plane were also mainly sweets. There was one nice baked cheddar option but it quickly ran out.
WestJet
7.2
Good
2,978 reviews
Delta
8.0
Very good
7,981 reviews
Check prices

Comfort

7.9

Crew

8.5

Food

7.3

Overall

8.0

Boarding

8.2

Entertainment

7.9

Reviews

1 / 20
8.0
Excellent

Michael,Jul 2025

AMS - ATL

Overall it was great experience, with the exception of snack food. The food offered in two main meals was just fine but for the mid-flight snack, the only option was a large cookie, too sweet and high sugar content. Snacks at the back of the plane were also mainly sweets. There was one nice baked cheddar option but it quickly ran out.
Air Canada
7.1
Good
9,851 reviews
Delta
8.0
Very good
7,981 reviews
Check prices

Comfort

7.9

Crew

8.5

Food

7.3

Overall

8.0

Boarding

8.2

Entertainment

7.9

Reviews

1 / 20
8.0
Excellent

Michael,Jul 2025

AMS - ATL

Overall it was great experience, with the exception of snack food. The food offered in two main meals was just fine but for the mid-flight snack, the only option was a large cookie, too sweet and high sugar content. Snacks at the back of the plane were also mainly sweets. There was one nice baked cheddar option but it quickly ran out.

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.

  • What are the cheapest airlines to fly from Region of Ontario to St. Louis one-way?

    For one-way options, check prices for American Airlines. According to our data, you can fly for as low as C$ 263. Users have also found prices from C$ 273 and C$ 317 on Iberia and United Airlines, respectively.

  • 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 Jazz (82%), Air Canada (81%) or United Airlines (72%) 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$ 629, our data indicates the cheapest price to be C$ 303. The most popular route (Toronto Pearson Intl - Lambert-St Louis), is priced around C$ 475.

  • 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, January is the cheapest month in which you can book a flight from Region of Ontario to St. Louis (average of C$ 365). Flying from Region of Ontario to St. Louis in September is currently the most expensive (average of C$ 491). 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

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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.
Pearson Intl to St. Louis flights
Pearson Intl to Kansas City flights
Pierre Elliott Trudeau Intl to St. Louis flights
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Comox to Kansas City flights
Pearson Intl to Columbia flights
Calgary to Columbia flights
Edmonton to Columbia flights
Pierre Elliott Trudeau Intl to Cape Girardeau flights

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 31 July 2025.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapestC$ 472AverageC$ 786FlexibilityNo cancel feeOn-time67%
Search Air Canada flights
DeltaCheapestC$ 475AverageC$ 614FlexibilityNo cancel feeOn-timeN/A
Search Delta flights
United AirlinesCheapestC$ 480AverageC$ 677FlexibilityNo cancel feeOn-time69%
Search United Airlines flights
WestJetCheapestC$ 558AverageC$ 870FlexibilityNo 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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