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$155+ 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 8/25. Fares are subject to change and may not be available on all flights or dates of travel.
STL — YYZ
יולי 18 — יולי 251
ש' 7/18
ש' 7/25
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 יוני 18, 2026.

This American Airlines deal was found by Cheapflights users on 6/17. 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.
ג' 7/216:55 am
STL
-
YYZ
1 stop9h 39m
American Airlines
ג' 7/281:17 pm
YYZ
-
STL
1 stop11h 59m
American Airlines
Deal found 6/17$368
This American Airlines deal was found by Cheapflights users on 6/14. 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.
ש' 9/58:06 pm
STL
-
YYZ
1 stop13h 53m
American Airlines
ד' 9/91:15 pm
YYZ
-
STL
1 stop12h 12m
American Airlines
Deal found 6/14$394
This American Airlines deal was found by Cheapflights users on 6/18. 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.
ש' 8/85:00 am
STL
-
YYZ
1 stop12h 30m
American Airlines
ד' 8/127:20 am
YYZ
-
STL
1 stop10h 04m
American Airlines
Deal found 6/18$411
This Kiwi.com deal was found by Cheapflights users on 6/15. 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.
ה' 7/307:10 pm
STL
-
YYZ
1 stop10h 29m
Multiple Airlines
ה' 8/63:50 pm
YYZ
-
STL
2 stops27h 25m
Multiple Airlines
Deal found 6/15$413
This Kiwi.com deal was found by Cheapflights users on 6/16. 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.
ג' 7/147:03 pm
STL
-
YYZ
2 stops29h 02m
Multiple Airlines
ג' 7/218:35 pm
YYZ
-
STL
1 stop22h 30m
Multiple Airlines
Deal found 6/16$419
This Kiwi.com deal was found by Cheapflights users on 6/15. 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.
ד' 8/266:58 pm
STL
-
YYZ
2 stops25h 17m
Multiple Airlines
ב' 8/317:00 am
YYZ
-
STL
1 stop13h 36m
Multiple Airlines
Deal found 6/15$420
This Kiwi.com deal was found by Cheapflights users on 6/16. 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.
ה' 7/167:10 pm
STL
-
YYZ
1 stop10h 29m
Multiple Airlines
א' 7/192:50 pm
YYZ
-
STL
2 stops28h 25m
Multiple Airlines
Deal found 6/16$425
This American Airlines deal was found by Cheapflights users on 6/14. 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.
ג' 10/68:05 pm
STL
-
YUL
1 stop14h 15m
American Airlines
ג' 10/1312:30 pm
YUL
-
STL
1 stop8h 38m
American Airlines
Deal found 6/14$427
This Kiwi.com deal was found by Cheapflights users on 6/17. 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.
ש' 8/14:57 pm
STL
-
YYZ
2 stops29h 38m
Multiple Airlines
ש' 8/88:35 pm
YYZ
-
STL
1 stop22h 40m
Multiple Airlines
Deal found 6/17$428
This Kiwi.com deal was found by Cheapflights users on 6/14. 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.
ג' 7/287:03 pm
STL
-
YYZ
1 stop10h 36m
Multiple Airlines
א' 8/24:45 pm
YYZ
-
STL
2 stops21h 36m
Multiple Airlines
Deal found 6/14$435
This Kiwi.com deal was found by Cheapflights users on 6/14. 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.
ב' 7/67:10 pm
STL
-
YYZ
1 stop20h 59m
Multiple Airlines
א' 7/124:45 pm
YYZ
-
STL
2 stops21h 36m
Multiple Airlines
Deal found 6/14$437
This Kiwi.com deal was found by Cheapflights users on 6/13. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
ש' 8/225:33 pm
STL
-
YYZ
2 stops17h 27m
Multiple Airlines
ג' 8/257:00 am
YYZ
-
STL
1 stop12h 08m
Multiple Airlines
Deal found 6/13$440

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 יוני 18, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$368
(American Airlines)

One-way from

$155
(American Airlines)

Popular in

November

Cheapest in

December

Average price

$559

Good round-trip deal

$373 or less

Good one-way deal

$402 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
High demand for flights, 3% potential price rise
Search Deals
Cheapest flight prices on average. 1% potential price decrease ($7 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in June 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 יוני 18, 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

ג' 7/21

6:55 am-5:34 pm

1 stop9h 39m

Toronto Pearson Intl

ג' 7/28

1:17 pm-12:16 am

1 stop11h 59m

$368

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

ג' 7/14

8:55 am-3:10 pm

1 stop5h 15m

Ottawa

ד' 7/15

2:35 pm-6:42 pm

1 stop5h 07m

$484

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

ד' 7/15

7:20 am-1:59 pm

1 stop5h 39m

Ottawa

ד' 7/22

5:50 pm-11:44 pm

1 stop6h 54m

$487

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

ב' 7/20

6:01 am-10:05 pm

1 stop15h 04m

Ottawa

ד' 7/22

5:50 pm-11:44 pm

1 stop6h 54m

$487

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

ו' 7/17

5:59 pm-10:03 am

2 stops15h 04m

Ottawa

ד' 7/22

6:25 am-12:11 pm

1 stop6h 46m

$497

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

ג' 7/14

6:00 am-2:17 pm

2 stops7h 17m

Ottawa

ד' 7/15

3:10 pm-11:44 pm

1 stop9h 34m

$497

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

ה' 9/17

8:00 am-11:54 pm

2 stops14h 54m

Ottawa

א' 9/20

6:00 am-3:38 pm

3 stops10h 38m

$549

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

א' 10/18

12:10 pm-7:53 pm

1 stop6h 43m

Toronto Pearson Intl

ב' 10/26

2:15 pm-3:30 pm

Nonstop2h 15m

$578

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

ו' 10/2

10:27 am-3:46 pm

1 stop4h 19m

Toronto Pearson Intl

ב' 10/5

6:55 pm-8:00 pm

Nonstop2h 05m

$580

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

ו' 9/4

5:30 pm-12:13 am

1 stop5h 43m

Toronto Pearson Intl

ב' 9/7

2:00 pm-6:42 pm

1 stop5h 42m

$584

Flights are sorted by cheapest round-trip flights first.

Deals found on 6/16

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

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 יוני 18, 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.

Weekly flight availability from St. Louis to Region of Ontario

Explore weekly flight availability from St. Louis to Ontario. 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 יוני 18, 2026.

The most flights from STL to CAON 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).

How much does it cost to fly round-trip from St. Louis to Region of 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.

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 יוני 18, 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
7.8
Good
8,410 reviews

Crew

8.5

Boarding

8.1

Food

7.2

Entertainment

7.8

Comfort

7.8

Overall

7.8

Reviews

1 / 20
10.0
Excellent

Anonymous,May 2026

SEA - KOA

The snacks were not very good, not everyone was very friendly and professional
Delta
7.8
Good
8,410 reviews
Delta
7.8
Good
8,410 reviews

Crew

8.5

Boarding

8.1

Food

7.2

Entertainment

7.8

Comfort

7.8

Overall

7.8

Reviews

1 / 20
10.0
Excellent

Anonymous,May 2026

SEA - KOA

The snacks were not very good, not everyone was very friendly and professional
United Airlines
7.4
Good
9,859 reviews
Delta
7.8
Good
8,410 reviews

Crew

8.5

Boarding

8.1

Food

7.2

Entertainment

7.8

Comfort

7.8

Overall

7.8

Reviews

1 / 20
10.0
Excellent

Anonymous,May 2026

SEA - KOA

The snacks were not very good, not everyone was very friendly and professional
American Airlines
7.1
Good
11,688 reviews
Delta
7.8
Good
8,410 reviews

Crew

8.5

Boarding

8.1

Food

7.2

Entertainment

7.8

Comfort

7.8

Overall

7.8

Reviews

1 / 20
10.0
Excellent

Anonymous,May 2026

SEA - KOA

The snacks were not very good, not everyone was very friendly and professional
Air Canada
7.1
Good
11,212 reviews
Delta
7.8
Good
8,410 reviews

Crew

8.5

Boarding

8.1

Food

7.2

Entertainment

7.8

Comfort

7.8

Overall

7.8

Reviews

1 / 20
10.0
Excellent

Anonymous,May 2026

SEA - KOA

The snacks were not very good, not everyone was very friendly and professional

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 15m. 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 $160 and Delta from $208 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 (73%), Jazz (70%) or United Airlines (49%) 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 $578, our data indicates the cheapest price to be $225. The most popular route (Lambert-St Louis - Toronto Pearson Intl), is priced around $419.

  • 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

Browse thousands of different options on Cheapflights for your next trip

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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 יוני 18, 2026.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapest$139Average$570FlexibilityNo cancel feeOn-time67%
United AirlinesCheapest$203Average$583FlexibilityNo cancel feeOn-time69%
American AirlinesCheapest$270Average$545FlexibilityNo cancel feeOn-time71%

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