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St. Louis

$186+ 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 9/30. Fares are subject to change and may not be available on all flights or dates of travel.
YYZ — STL
ago. 4 — ago. 111
lun. 8/4
lun. 8/11
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 julio 30, 2025.

Round-trip from

$321
(American Airlines)

One-way from

$174
(Kiwi.com)

Popular in

August

Cheapest in

June

Average price

$493

Good round-trip deal

$576 or less

Good one-way deal

$345 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. 4% potential increase in price ($24 potential increase over avg. RT price).
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Cheapest flight prices on average. 1% potential price decrease ($8 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 julio 30, 2025.

This American Airlines deal was found by Cheapflights users on 7/27. 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.
sáb. 10/111:15 pmYYZ - STL
1 stop11h 39mAmerican Airlines
mié. 10/227:16 amSTL - YYZ
1 stop9h 24mAmerican Airlines
Deal found 7/27$313
This American Airlines deal was found by Cheapflights users on 7/30. 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.
sáb. 9/1312:31 pmYUL - STL
1 stop10h 22mAmerican Airlines
sáb. 9/202:01 pmSTL - YUL
1 stop20h 45mAmerican Airlines
Deal found 7/30$326
This Air Canada deal was found by Cheapflights users on 7/29. 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.
vie. 9/122:15 pmYYZ - STL
Nonstop2h 03mAir Canada
dom. 9/144:05 pmSTL - YYZ
Nonstop1h 55mAir Canada
Deal found 7/29$352
This TravelUp deal was found by Cheapflights users on 7/28. 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 TravelUp is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
vie. 8/226:21 pmYYZ - STL
1 stop22h 28mMultiple Airlines
mié. 9/106:10 amSTL - YYZ
1 stop10h 33mMultiple Airlines
Deal found 7/28$369
This United Airlines deal was found by Cheapflights users on 7/27. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
mié. 10/159:00 amYYZ - STL
1 stop7h 44mUnited Airlines
dom. 10/1912:25 pmSTL - YYZ
1 stop7h 19mUnited Airlines
Deal found 7/27$400
This Delta deal was found by Cheapflights users on 7/29. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
lun. 9/86:04 amYYZ - STL
1 stop11h 45mDelta
jue. 9/116:05 amSTL - YYZ
1 stop9h 03mDelta
Deal found 7/29$407
This Delta deal was found by Cheapflights users on 7/29. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
lun. 9/86:00 amYUL - STL
1 stop27h 06mDelta
mar. 9/166:40 amSTL - YUL
1 stop4h 20mDelta
Deal found 7/29$408
This Air Canada deal was found by Cheapflights users on 7/29. 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.
lun. 9/86:10 pmYUL - STL
Nonstop2h 47mAir Canada
mar. 9/169:15 amSTL - YUL
1 stop6h 05mAir Canada
Deal found 7/29$427
This United Airlines deal was found by Cheapflights users on 7/29. 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.
lun. 9/88:00 pmYUL - STL
2 stops20h 44mUnited Airlines
mar. 9/165:30 pmSTL - YUL
1 stop17h 27mUnited Airlines
Deal found 7/29$445
This Kiwi.com deal was found by Cheapflights users on 7/29. 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.
sáb. 8/24:25 pmYOW - STL
1 stop8h 22mMultiple Airlines
mar. 8/55:40 pmSTL - YOW
1 stop22h 26mMultiple Airlines
Deal found 7/29$463
This Mytrip deal was found by Cheapflights users on 7/29. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
vie. 9/127:00 amYUL - STL
3 stops10h 35mMultiple Airlines
vie. 9/191:00 pmSTL - YUL
3 stops25h 20mMultiple Airlines
Deal found 7/29$481
This United Airlines deal was found by Cheapflights users on 7/29. 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.
mar. 8/267:29 pmYOW - STL
2 stops16h 17mUnited Airlines
mar. 9/27:04 pmSTL - YOW
2 stops18h 22mUnited Airlines
Deal found 7/29$570

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 julio 30, 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

sáb. 10/11

1:15 pm-11:54 pm

1 stop11h 39m

Lambert-St Louis

mié. 10/22

7:16 am-5:40 pm

1 stop9h 24m

$313

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

sáb. 9/13

12:31 pm-9:53 pm

1 stop10h 22m

Lambert-St Louis

sáb. 9/20

2:01 pm-11:46 am

1 stop20h 45m

$326

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

vie. 9/12

2:15 pm-3:18 pm

Nonstop2h 03m

Lambert-St Louis

dom. 9/14

4:05 pm-7:00 pm

Nonstop1h 55m

$352

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

vie. 8/22

6:21 pm-3:49 pm

1 stop22h 28m

Lambert-St Louis

mié. 9/10

6:10 am-5:43 pm

1 stop10h 33m

$369

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

mié. 10/15

9:00 am-3:44 pm

1 stop7h 44m

Lambert-St Louis

dom. 10/19

12:25 pm-8:44 pm

1 stop7h 19m

$400

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

lun. 9/8

6:04 am-4:49 pm

1 stop11h 45m

Lambert-St Louis

jue. 9/11

6:05 am-4:08 pm

1 stop9h 03m

$407

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

lun. 9/8

6:00 am-8:06 am

1 stop27h 06m

Lambert-St Louis

mar. 9/16

6:40 am-12:00 pm

1 stop4h 20m

$408

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

lun. 9/8

6:10 pm-7:57 pm

Nonstop2h 47m

Lambert-St Louis

mar. 9/16

9:15 am-4:20 pm

1 stop6h 05m

$427

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

lun. 9/8

8:00 pm-3:44 pm

2 stops20h 44m

Lambert-St Louis

mar. 9/16

5:30 pm-11:57 am

1 stop17h 27m

$445

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

sáb. 8/2

4:25 pm-11:47 pm

1 stop8h 22m

Lambert-St Louis

mar. 8/5

5:40 pm-5:06 pm

1 stop22h 26m

$463

Flights are sorted by cheapest round-trip flights first.

Deals found on 7/28

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, 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 julio 30, 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 julio 30, 2025.

The most flights from CAON to STL are scheduled on a Monday (4 on average). You will have fewer flight options on Friday, 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 julio 30, 2025.
Read reviews from past customers who have flown Delta, United Airlines, and American Airlines from Ontario to St. Louis. Reviews also offer insight into each airline's entertainment options, comfort, food, crew/service, and boarding process.
Delta
8.0
Very good
7,980 reviews

Boarding

8.2

Crew

8.5

Comfort

7.9

Overall

8.0

Food

7.3

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
7,980 reviews
Delta
8.0
Very good
7,980 reviews

Boarding

8.2

Crew

8.5

Comfort

7.9

Overall

8.0

Food

7.3

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
8,896 reviews
Delta
8.0
Very good
7,980 reviews

Boarding

8.2

Crew

8.5

Comfort

7.9

Overall

8.0

Food

7.3

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
7,980 reviews

Boarding

8.2

Crew

8.5

Comfort

7.9

Overall

8.0

Food

7.3

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
2,975 reviews
Delta
8.0
Very good
7,980 reviews

Boarding

8.2

Crew

8.5

Comfort

7.9

Overall

8.0

Food

7.3

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
9,837 reviews
Delta
8.0
Very good
7,980 reviews

Boarding

8.2

Crew

8.5

Comfort

7.9

Overall

8.0

Food

7.3

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?

    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.

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

    $190 is the cheapest one-way deal found within the past few days, from American Airlines. You may also be able to find cheap deals on Iberia and Air Canada, with prices starting from $197 and $210, 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?

    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: Jazz (82%), Air Canada (81%), United Airlines (72%).

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

    The cheapest flight price from Region of Ontario to St. Louis is $247. On average you can expect to pay $497. The most popular route, (Toronto Pearson Intl - Lambert-St Louis), can usually be booked for $359.

  • 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
O'Fallon
Maryland Heights
Fairview Heights
Collinsville
Eureka
St. Peters
Glencoe
Alton
Chesterfield
Festus
Farmington

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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.
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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 julio 30, 2025.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapest$324Average$492FlexibilityNo cancel feeOn-time67%

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