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$143+ Cheap flights from St. Louis (STL) to Ontario

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 6/9. Fares are subject to change and may not be available on all flights or dates of travel.
STL — YYZ
May 31 — Jun 71
Sun 5/31
Sun 6/7
1 adult, Economy
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Cheap 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 May 1, 2026.

This Kiwi.com deal was found by Cheapflights users on 4/28. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/286:33 pm
STL
-
YYZ
2 stops42h 32m
Multiple Airlines
Thu 6/49:50 am
YYZ
-
STL
1 stop15h 07m
Multiple Airlines
Deal found 4/28$335
This Kiwi.com deal was found by Cheapflights users on 4/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/275:27 pm
STL
-
YYZ
2 stops26h 33m
Multiple Airlines
Wed 6/37:45 am
YYZ
-
STL
1 stop17h 12m
Multiple Airlines
Deal found 4/27$359
This American Airlines deal was found by Cheapflights users on 4/28. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/276:00 am
STL
-
YYZ
1 stop10h 44m
American Airlines
Wed 6/311:39 am
YYZ
-
STL
1 stop9h 51m
American Airlines
Deal found 4/28$367
This Kiwi.com deal was found by Cheapflights users on 4/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/24:19 pm
STL
-
YYZ
2 stops28h 36m
Multiple Airlines
Sat 6/67:45 am
YYZ
-
STL
1 stop17h 12m
Multiple Airlines
Deal found 4/27$373
This Air Canada deal was found by Cheapflights users on 4/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/22:15 pm
STL
-
YOW
1 stop6h 01m
Air Canada
Thu 6/43:00 pm
YOW
-
STL
1 stop6h 25m
Air Canada
Deal found 4/27$378
This United Airlines deal was found by Cheapflights users on 4/28. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/26:00 am
STL
-
YOW
1 stop9h 38m
United Airlines
Thu 6/46:25 am
YOW
-
STL
1 stop6h 46m
United Airlines
Deal found 4/28$381
This Air Canada deal was found by Cheapflights users on 4/29. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/121:05 pm
STL
-
YOW
1 stop5h 36m
Air Canada
Sat 5/163:00 pm
YOW
-
STL
1 stop6h 25m
Air Canada
Deal found 4/29$384
This American Airlines deal was found by Cheapflights users on 4/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/231:45 pm
STL
-
YYZ
1 stop8h 44m
American Airlines
Tue 6/307:25 am
YYZ
-
STL
1 stop10h 08m
American Airlines
Deal found 4/27$387
This United Airlines deal was found by Cheapflights users on 4/28. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 6/106:00 am
STL
-
YOW
2 stops11h 48m
United Airlines
Wed 6/176:25 am
YOW
-
STL
1 stop10h 21m
United Airlines
Deal found 4/28$391
This United Airlines deal was found by Cheapflights users on 4/29. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/81:13 pm
STL
-
YOW
1 stop7h 22m
United Airlines
Sat 8/156:00 pm
YOW
-
STL
1 stop6h 37m
United Airlines
Deal found 4/29$392
This American Airlines deal was found by Cheapflights users on 4/26. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/276:00 am
STL
-
YYZ
1 stop7h 30m
American Airlines
Thu 5/281:15 pm
YYZ
-
STL
1 stop8h 15m
American Airlines
Deal found 4/26$394
This Kiwi.com deal was found by Cheapflights users on 4/29. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/275:27 pm
STL
-
YYZ
2 stops19h 38m
Multiple Airlines
Sat 5/307:45 am
YYZ
-
STL
1 stop17h 12m
Multiple Airlines
Deal found 4/29$395

Find 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 May 1, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$335
(Kiwi.com)

One-way from

$143
(Kiwi.com)

Popular in

November

Cheapest in

June

Average price

$488

Good round-trip deal

$810 or less

Good one-way deal

$354 or less
Provider with most accurate pricing for Lambert-St Louis-Toronto (YTO) flight deals.
Search Deals
Provider most trusted by Cheapflights users for Lambert-St Louis-Toronto (YTO) flights.
Search Deals
From Lambert-St Louis to Ontario
Search Deals
One-way flight from Lambert-St Louis to Ontario
Search Deals
Highest demand for flights based on searches. 4% potential increase in price ($23 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($11 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in May 2026
Search Deals
Price to beat on a round-trip flight from Lambert-St Louis to Ontario.
Search Deals
Price to beat on a one-way flight from Lambert-St Louis to Ontario.
Search Deals

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 2,558,603 searches. Data last updated May 1, 2026.
Use the filters below to find and compare flights from St. Louis to Ontario that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Wed 5/27

2:36 pm-11:24 pm

1 stop7h 48m

Toronto Pearson Intl

Wed 6/3

1:15 pm-12:14 am

1 stop11h 59m

$376

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

Wed 6/10

8:40 am-3:11 pm

1 stop5h 31m

Ottawa

Wed 6/17

2:40 pm-8:25 pm

1 stop6h 45m

$378

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

Tue 6/2

2:15 pm-9:16 pm

1 stop6h 01m

Ottawa

Thu 6/4

2:40 pm-8:25 pm

1 stop6h 45m

$378

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

Tue 6/2

6:00 am-4:38 pm

1 stop9h 38m

Ottawa

Thu 6/4

6:25 am-12:11 pm

1 stop6h 46m

$381

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

Sat 6/13

6:00 am-9:35 pm

1 stop14h 35m

Ottawa

Sat 6/20

3:10 pm-11:35 pm

1 stop9h 25m

$381

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

Tue 5/12

1:05 pm-7:41 pm

1 stop5h 36m

Ottawa

Sat 5/16

3:00 pm-8:25 pm

1 stop6h 25m

$384

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

Tue 6/2

2:15 pm-9:16 pm

1 stop6h 01m

Ottawa

Wed 6/3

2:40 pm-8:25 pm

1 stop6h 45m

$389

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

Wed 6/10

6:00 am-6:48 pm

2 stops11h 48m

Ottawa

Wed 6/17

6:25 am-3:46 pm

1 stop10h 21m

$391

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

Sat 8/8

1:13 pm-9:35 pm

1 stop7h 22m

Ottawa

Sat 8/15

6:00 pm-11:37 pm

1 stop6h 37m

$392

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Mon 5/25

5:10 am-3:14 pm

1 stop9h 04m

Toronto Pearson Intl

Mon 5/25

5:15 pm-10:52 pm

1 stop6h 37m

$504

Flights are sorted by cheapest round-trip flights first.

Deals found on 4/26

Showing 1-10 of 54 resultsSorted by cheapest first
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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

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

To ensure you get the cheapest price possible for a flight from St. Louis to Region of Ontario, you should look to book at least 88 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.

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 $139). Flying from St. Louis to Region of Ontario in January is currently the most expensive (average of $468). 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 May 1, 2026.

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 May 1, 2026.
Get a feel of what it's like to fly with Delta,United Airlines, andAmerican Airlines from St. Louis to Ontario by reading reviews from past customers. You can also see how each airline compares in terms of entertainment options, comfort, food, crew/service, and boarding process.
Delta
7.9
Good
8,464 reviews

Boarding

8.1

Crew

8.5

Comfort

7.9

Entertainment

7.8

Overall

7.9

Food

7.2

Reviews

1 / 20
6.0
Good

Jim,Nov 2025

AVL - ATL

The exit row seats without a seat in front are great for leg room but don’t have a fold out entertainment console so you’re forced to use the screen several feet in front of you (there is, at least, a remote). Best to bring a tablet loaded with entertainment or a book.
Delta
7.9
Good
8,464 reviews
Delta
7.9
Good
8,464 reviews

Boarding

8.1

Crew

8.5

Comfort

7.9

Entertainment

7.8

Overall

7.9

Food

7.2

Reviews

1 / 20
6.0
Good

Jim,Nov 2025

AVL - ATL

The exit row seats without a seat in front are great for leg room but don’t have a fold out entertainment console so you’re forced to use the screen several feet in front of you (there is, at least, a remote). Best to bring a tablet loaded with entertainment or a book.
United Airlines
7.4
Good
9,677 reviews
Delta
7.9
Good
8,464 reviews

Boarding

8.1

Crew

8.5

Comfort

7.9

Entertainment

7.8

Overall

7.9

Food

7.2

Reviews

1 / 20
6.0
Good

Jim,Nov 2025

AVL - ATL

The exit row seats without a seat in front are great for leg room but don’t have a fold out entertainment console so you’re forced to use the screen several feet in front of you (there is, at least, a remote). Best to bring a tablet loaded with entertainment or a book.
American Airlines
7.1
Good
11,684 reviews
Delta
7.9
Good
8,464 reviews

Boarding

8.1

Crew

8.5

Comfort

7.9

Entertainment

7.8

Overall

7.9

Food

7.2

Reviews

1 / 20
6.0
Good

Jim,Nov 2025

AVL - ATL

The exit row seats without a seat in front are great for leg room but don’t have a fold out entertainment console so you’re forced to use the screen several feet in front of you (there is, at least, a remote). Best to bring a tablet loaded with entertainment or a book.
Air Canada
7.1
Good
10,983 reviews
Delta
7.9
Good
8,464 reviews

Boarding

8.1

Crew

8.5

Comfort

7.9

Entertainment

7.8

Overall

7.9

Food

7.2

Reviews

1 / 20
6.0
Good

Jim,Nov 2025

AVL - ATL

The exit row seats without a seat in front are great for leg room but don’t have a fold out entertainment console so you’re forced to use the screen several feet in front of you (there is, at least, a remote). Best to bring a tablet loaded with entertainment or a book.

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?

    Lambert-St Louis (STL) is the airport you will fly out of if you book a flight from St. Louis to Ontario. It is only a 12.7 mi journey to Lambert-St Louis (STL) from St. Louis’s city center.

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

    Departing from St. Louis to Region of Ontario will take you 5h 31m. Airlines will cover a distance of 878 mi. When browsing for deals, the options you’ll see will be for both nonstop flights and flights with stops.

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

    One-way options have recently been found by users for as low as $153 on United Airlines. Other airlines that offer cheap prices include Air Canada from $177 and Delta from $186 one-way.

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

    When deciding which route to take from St. Louis to Region of Ontario consider Lambert-St Louis - Toronto Pearson Intl, Lambert-St Louis - Montreal Pierre Elliott Trudeau Intl or Lambert-St Louis - Ottawa as they are the most popular.

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

    No one likes to see their flight delayed. When booking a flight from St. Louis to Region of Ontario consider choosing Air Canada (83%), Jazz (83%) or United Airlines (79%) as they are the most reliable in getting you off to your destination on time.

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

    Looking for the cheapest flight from St. Louis to Region of Ontario? While on average our users pay $1,381, our data indicates the cheapest price to be $189. The most popular route (Lambert-St Louis - Toronto Pearson Intl), is priced around $399.

  • 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 $139). Flying from St. Louis to Region of Ontario in January is currently the most expensive (average of $468). 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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Top 3 airlines flying from St. Louis to Ontario

Discover the top 3 airlines 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 2,558,603 searches. Data last updated May 1, 2026.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapest$139Average$651FlexibilityNo cancel feeOn-time67%
United AirlinesCheapest$199Average$629FlexibilityNo cancel feeOn-time69%
American AirlinesCheapest$270Average$558FlexibilityNo cancel feeOn-time71%

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