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St. Louis

$166+ Cheap flights from Ontario to St. Louis (STL)

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 10/4. Fares are subject to change and may not be available on all flights or dates of travel.
YYZ — STL
Oct 11 — Oct 181
Sat 10/11
Sat 10/18
1 adult, Economy
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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 September 11, 2025.

Round-trip from

$261
(Kiwi.com)

One-way from

$166
(Kiwi.com)

Popular in

January

Cheapest in

June

Average price

$476

Good round-trip deal

$405 or less

Good one-way deal

$245 or less
From Ontario to Lambert-St Louis
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One-way flight from Ontario to Lambert-St Louis
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Highest demand for flights based on searches. 6% potential increase in price ($31 potential increase over avg. RT price).
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Cheapest flight prices on average. 1% potential price decrease ($6 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 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 September 11, 2025.

This Kiwi.com deal was found by Cheapflights users on 9/11. 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 11/69:45 amYYZ - STL
1 stop29h 12mMultiple Airlines
Mon 11/109:07 pmSTL - YYZ
1 stop24h 53mMultiple Airlines
Deal found 9/11$261
This Kiwi.com deal was found by Cheapflights users on 9/11. 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 11/69:45 amYYZ - STL
1 stop29h 12mMultiple Airlines
Sat 11/84:51 pmSTL - YYZ
1 stop12h 29mMultiple Airlines
Deal found 9/11$264
This Kiwi.com deal was found by Cheapflights users on 9/11. 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.
Fri 11/79:45 amYYZ - STL
1 stop11h 27mMultiple Airlines
Mon 11/102:42 pmSTL - YYZ
2 stops21h 58mMultiple Airlines
Deal found 9/11$276
This Kiwi.com deal was found by Cheapflights users on 9/10. 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 10/156:30 amYYZ - STL
1 stop28h 32mMultiple Airlines
Mon 10/209:59 pmSTL - YYZ
2 stops21h 53mMultiple Airlines
Deal found 9/10$280
This Kiwi.com deal was found by Cheapflights users on 9/10. 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.
Sun 10/269:35 amYYZ - STL
2 stops24h 57mMultiple Airlines
Thu 10/3010:57 amSTL - YYZ
1 stop26h 43mMultiple Airlines
Deal found 9/10$283
This American Airlines deal was found by Cheapflights users on 9/9. 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 10/151:15 pmYYZ - STL
1 stop11h 39mAmerican Airlines
Tue 10/216:00 amSTL - YYZ
1 stop7h 30mAmerican Airlines
Deal found 9/9$297
This Kiwi.com deal was found by Cheapflights users on 9/9. 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 10/159:45 amYYZ - STL
2 stops24h 22mMultiple Airlines
Sun 10/1910:57 amSTL - YYZ
1 stop26h 08mMultiple Airlines
Deal found 9/9$305
This American Airlines deal was found by Cheapflights users on 9/9. 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 10/71:15 pmYYZ - STL
1 stop8h 11mAmerican Airlines
Tue 10/146:00 amSTL - YYZ
1 stop9h 34mAmerican Airlines
Deal found 9/9$319
This Kiwi.com deal was found by Cheapflights users on 9/11. 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 10/19:35 amYYZ - STL
1 stop25h 05mMultiple Airlines
Sun 10/54:00 pmSTL - YYZ
2 stops27h 55mMultiple Airlines
Deal found 9/11$320
This American Airlines deal was found by Cheapflights users on 9/9. 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 12/211:33 amYYZ - STL
1 stop13h 23mAmerican Airlines
Thu 12/46:00 amSTL - YYZ
1 stop9h 35mAmerican Airlines
Deal found 9/9$323
This Kiwi.com deal was found by Cheapflights users on 9/9. 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.
Fri 10/37:45 pmYYZ - STL
2 stops21h 18mMultiple Airlines
Mon 10/69:32 pmSTL - YYZ
1 stop15h 20mMultiple Airlines
Deal found 9/9$324
This Kiwi.com deal was found by Cheapflights users on 9/9. 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.
Fri 11/76:45 amYUL - STL
2 stops14h 27mMultiple Airlines
Fri 11/142:12 pmSTL - YUL
1 stop9h 18mMultiple Airlines
Deal found 9/9$367

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 2,558,603 searches. Data last updated September 11, 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

Fri 11/7

9:45 am-8:12 pm

1 stop11h 27m

Lambert-St Louis

Mon 11/10

2:42 pm-1:40 pm

2 stops21h 58m

$276

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Thu 11/6

9:45 am-9:07 am

2 stops24h 22m

Lambert-St Louis

Sat 11/8

4:51 pm-6:20 am

1 stop12h 29m

$304

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Wed 10/15

9:45 am-9:07 am

2 stops24h 22m

Lambert-St Louis

Sun 10/19

10:57 am-2:05 pm

1 stop26h 08m

$305

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Mon 10/6

4:00 pm-9:07 am

2 stops18h 07m

Lambert-St Louis

Mon 10/13

9:06 pm-10:40 pm

1 stop24h 34m

$337

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Fri 10/3

1:15 pm-9:53 pm

1 stop9h 38m

Lambert-St Louis

Mon 10/6

6:00 am-2:30 pm

1 stop7h 30m

$343

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Fri 10/24

8:05 pm-9:07 am

2 stops14h 02m

Lambert-St Louis

Fri 10/31

2:12 pm-2:20 pm

1 stop23h 08m

$349

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Mon 10/20

10:40 am-9:07 am

2 stops23h 27m

Lambert-St Louis

Thu 10/23

10:57 am-8:55 pm

1 stop8h 58m

$353

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Fri 10/24

1:15 pm-8:26 pm

1 stop8h 11m

Lambert-St Louis

Fri 10/31

10:13 am-11:25 pm

1 stop12h 12m

$357

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Sat 10/25

2:15 pm-3:18 pm

Nonstop2h 03m

Lambert-St Louis

Sun 11/2

4:05 pm-7:06 pm

Nonstop2h 01m

$358

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Mon 10/6

4:15 pm-8:20 pm

1 stop5h 05m

Lambert-St Louis

Wed 10/8

6:00 am-2:30 pm

1 stop7h 30m

$371

Flights are sorted by cheapest round-trip flights first.

Deals found on 9/9

Showing 1-10 of 44 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, August is the cheapest month in which you can book a flight from Region of Ontario to St. Louis (average of $311). Flying from Region of Ontario to St. Louis in March is currently the most expensive (average of $356). 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 September 11, 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 September 11, 2025.

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

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?

    Located just 12.7 mi from the city center, Lambert-St Louis (STL) is the airport most travelers will use when flying to St. Louis from Ontario.

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

    Departing from Region of Ontario to St. Louis will take you 9h 38m. The distance between Region of Ontario and St. Louis is about 653 mi. When browsing for deals, the options you’ll see will be for both nonstop flights and flights with stops.

  • 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?

    Looking for the most reliable airlines to get you to your destination on time? Our data shows these are most likely to get you from Region of Ontario to St. Louis on time: Air Canada (75%), Jazz (75%), United Airlines (75%).

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

    The cheapest flight price from Region of Ontario to St. Louis is $213. On average you can expect to pay $344. The most popular route, (Toronto Pearson Intl - Lambert-St Louis), can usually be booked for $280.

  • 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, August is the cheapest month in which you can book a flight from Region of Ontario to St. Louis (average of $311). Flying from Region of Ontario to St. Louis in March is currently the most expensive (average of $356). 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

Traveling to a place near St. Louis?

Book flights to St. Louis if you plan to visit one of these locations
Edwardsville
O'Fallon
Fairview Heights
Maryland Heights
Collinsville
Eureka
Glencoe
St. Peters
Chesterfield
Alton
Farmington
Festus

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Alternative routes for Ontario to St. Louis

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Top airline flying from Ontario to St. Louis

Discover the top airline 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 2,558,603 searches. Data last updated September 11, 2025.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapest$324Average$586FlexibilityNo cancel feeOn-time67%

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