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$84+ 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 1/18. Fares are subject to change and may not be available on all flights or dates of travel.
STL — YYZ
Jan 14 — Jan 211
Wed 1/14
Wed 1/21
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 December 15, 2025.

This Kiwi.com deal was found by Cheapflights users on 12/12. 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.
Sat 12/207:43 pmSTL - YYZ
2 stops17h 37mMultiple Airlines
Fri 2/67:10 amYYZ - STL
1 stop17h 23mMultiple Airlines
Deal found 12/12$553
This Kiwi.com deal was found by Cheapflights users on 12/12. 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 12/2511:51 amSTL - YYZ
1 stop10h 29mMultiple Airlines
Sat 12/275:15 pmYYZ - STL
1 stop4h 26mMultiple Airlines
Deal found 12/12$586
This American Airlines deal was found by Cheapflights users on 12/12. 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 12/246:00 pmSTL - YYZ
1 stop17h 25mAmerican Airlines
Fri 12/261:14 pmYYZ - STL
1 stop11h 41mAmerican Airlines
Deal found 12/12$588
This Kiwi.com deal was found by Cheapflights users on 12/14. 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.
Sat 12/207:43 pmSTL - YYZ
2 stops34h 04mMultiple Airlines
Sat 1/317:10 amYYZ - STL
1 stop17h 23mMultiple Airlines
Deal found 12/14$610
This Kiwi.com deal was found by Cheapflights users on 12/14. 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 12/1811:51 amSTL - YYZ
1 stop10h 29mMultiple Airlines
Sun 12/217:10 amYYZ - STL
2 stops27h 52mMultiple Airlines
Deal found 12/14$617
This Kiwi.com deal was found by Cheapflights users on 12/15. 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 12/2511:51 amSTL - YYZ
1 stop22h 52mMultiple Airlines
Thu 1/17:10 amYYZ - STL
1 stop16h 23mMultiple Airlines
Deal found 12/15$628
This United Airlines deal was found by Cheapflights users on 12/12. 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.
Fri 12/266:35 pmSTL - YYZ
1 stop4h 24mUnited Airlines
Sun 12/286:50 amYYZ - STL
1 stop6h 37mUnited Airlines
Deal found 12/12$639
This Kiwi.com deal was found by Cheapflights users on 12/14. 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 12/1811:51 amSTL - YYZ
1 stop10h 29mMultiple Airlines
Mon 12/227:10 amYYZ - STL
1 stop16h 23mMultiple Airlines
Deal found 12/14$651
This American Airlines deal was found by Cheapflights users on 12/13. 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 12/308:01 pmSTL - YUL
1 stop18h 09mAmerican Airlines
Thu 1/83:50 pmYUL - STL
1 stop19h 30mAmerican Airlines
Deal found 12/13$682
This Delta deal was found by Cheapflights users on 12/14. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 12/305:59 pmSTL - YUL
1 stop4h 20mDelta
Thu 1/89:34 amYUL - STL
2 stops12h 03mDelta
Deal found 12/14$719
This Kiwi.com deal was found by Cheapflights users on 12/14. 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 12/2511:51 amSTL - YUL
1 stop11h 54mMultiple Airlines
Mon 12/2910:15 amYUL - STL
2 stops37h 18mMultiple Airlines
Deal found 12/14$796
This American Airlines deal was found by Cheapflights users on 12/14. 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 12/316:00 amSTL - YUL
1 stop8h 10mAmerican Airlines
Mon 1/53:50 pmYUL - STL
1 stop19h 30mAmerican Airlines
Deal found 12/14$848

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 December 15, 2025.

Most accurate provider

eDreams
3 stars

Most trusted provider

eDreams
3 stars

Round-trip from

$245
(Kiwi.com)

One-way from

$84
(Kiwi.com)

Popular in

November

Cheapest in

April

Average price

$492

Good round-trip deal

$541 or less

Good one-way deal

$479 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. 13% potential increase in price ($78 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease ($17 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in December 2025
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 December 15, 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

Sun 1/11

9:46 pm-6:20 am

1 stop31h 34m

Toronto Pearson Intl

Fri 1/16

7:10 am-10:34 pm

1 stop16h 24m

$245

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Wed 1/28

8:22 pm-11:20 pm

2 stops25h 58m

Toronto Pearson Intl

Wed 2/4

5:15 pm-11:33 pm

1 stop7h 18m

$275

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sun 1/25

5:42 pm-2:20 pm

1 stop19h 38m

Toronto Pearson Intl

Sat 1/31

7:10 am-11:33 pm

1 stop17h 23m

$293

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Tue 1/13

5:11 pm-2:16 pm

1 stop20h 05m

Toronto Pearson Intl

Tue 1/20

7:15 am-11:33 pm

1 stop17h 18m

$304

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Fri 1/16

10:09 pm-1:40 pm

2 stops38h 31m

Toronto Pearson Intl

Thu 1/22

5:15 pm-10:23 am

1 stop18h 08m

$308

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Fri 3/6

7:52 am-12:14 am

1 stop15h 22m

Toronto Pearson Intl

Mon 3/9

8:20 pm-11:19 pm

1 stop27h 59m

$317

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sat 2/14

6:35 pm-10:56 am

1 stop15h 21m

Toronto Pearson Intl

Sat 2/21

11:38 am-6:02 pm

1 stop7h 24m

$351

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Mon 2/2

6:44 pm-3:08 pm

1 stop19h 24m

Montreal Pierre Elliott Trudeau Intl

Wed 2/4

3:50 pm-10:20 am

1 stop19h 30m

$354

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

Wed 3/4

4:05 pm-11:08 pm

1 stop6h 03m

Ottawa

Wed 3/18

10:20 am-3:29 pm

1 stop6h 09m

$361

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

Mon 2/2

4:05 pm-11:08 pm

1 stop6h 03m

Ottawa

Thu 2/5

10:20 am-3:29 pm

1 stop6h 09m

$361

Flights are sorted by cheapest round-trip flights first.

Deals found on 12/14

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, June is the cheapest month in which you can book a flight from St. Louis to Region of Ontario (average of $179). Flying from St. Louis to Region of Ontario in October is currently the most expensive (average of $516). 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 December 15, 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 December 15, 2025.
Get a feel of what it's like to fly with Delta, United Airlines, and American 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
8,008 reviews

Crew

8.5

Entertainment

7.9

Boarding

8.1

Comfort

7.9

Food

7.3

Overall

7.9

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
8,008 reviews
Delta
7.9
Good
8,008 reviews

Crew

8.5

Entertainment

7.9

Boarding

8.1

Comfort

7.9

Food

7.3

Overall

7.9

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
9,092 reviews
Delta
7.9
Good
8,008 reviews

Crew

8.5

Entertainment

7.9

Boarding

8.1

Comfort

7.9

Food

7.3

Overall

7.9

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
7.2
Good
11,051 reviews
Delta
7.9
Good
8,008 reviews

Crew

8.5

Entertainment

7.9

Boarding

8.1

Comfort

7.9

Food

7.3

Overall

7.9

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
10,525 reviews
Delta
7.9
Good
8,008 reviews

Crew

8.5

Entertainment

7.9

Boarding

8.1

Comfort

7.9

Food

7.3

Overall

7.9

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 08m. 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 $177 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 (94%), Jazz (94%) or United Airlines (94%) 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 $1,404, our data indicates the cheapest price to be $209. The most popular route (Lambert-St Louis - Toronto Pearson Intl), is priced around $245.

  • 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 $179). Flying from St. Louis to Region of Ontario in October is currently the most expensive (average of $516). 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.
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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 December 15, 2025.
AirlineCheapestAverageFlexibilityOn-time
United AirlinesCheapest$199Average$664FlexibilityNo cancel feeOn-time69%
Air CanadaCheapest$220Average$684FlexibilityNo cancel feeOn-time67%
American AirlinesCheapest$270Average$558FlexibilityNo cancel feeOn-time71%

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