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Cheap flights from St. Louis to Ontario from C$ 224

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 7/5. Fares are subject to change and may not be available on all flights or dates of travel.
STL — YYZ
18 Apr — 25 Apr1
1 adult
1 adult, Economy, 0 bags

Cheap flight deals from St. Louis to Ontario

Enter your travel dates to find the best prices.

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 19 March 2026.

Tue 14/44:30 p.m.
STL
-
YUL
1 stop18h 14m
American Airlines
Tue 21/412:30 p.m.
YUL
-
STL
1 stop10h 49m
American Airlines
Deal found 17/3C$ 476
Mon 13/48:41 a.m.
STL
-
YYZ
1 stop14h 33m
Multiple Airlines
Sun 19/46:30 a.m.
YYZ
-
STL
2 stops25h 20m
Multiple Airlines
Deal found 16/3C$ 526
Wed 29/48:03 p.m.
STL
-
YUL
1 stop14h 41m
American Airlines
Mon 4/512:30 p.m.
YUL
-
STL
1 stop12h 16m
American Airlines
Deal found 17/3C$ 526
Mon 13/44:59 p.m.
STL
-
YYZ
1 stop20h 17m
Multiple Airlines
Mon 20/49:35 a.m.
YYZ
-
STL
2 stops46h 15m
Multiple Airlines
Deal found 16/3C$ 533
Wed 8/44:59 p.m.
STL
-
YYZ
1 stop20h 21m
Multiple Airlines
Thu 9/48:20 p.m.
YYZ
-
STL
1 stop12h 31m
Multiple Airlines
Deal found 16/3C$ 563
Sat 2/54:30 p.m.
STL
-
YUL
1 stop18h 14m
American Airlines
Mon 4/512:30 p.m.
YUL
-
STL
1 stop12h 16m
American Airlines
Deal found 17/3C$ 578
Mon 6/46:33 p.m.
STL
-
YUL
1 stop16h 11m
American Airlines
Sat 11/412:30 p.m.
YUL
-
STL
1 stop8h 39m
American Airlines
Deal found 15/3C$ 579
Wed 1/44:54 p.m.
STL
-
YYZ
1 stop20h 26m
Multiple Airlines
Mon 6/43:40 p.m.
YYZ
-
STL
2 stops19h 50m
Multiple Airlines
Deal found 16/3C$ 597
Wed 1/44:54 p.m.
STL
-
YYZ
1 stop20h 26m
Multiple Airlines
Wed 8/43:40 p.m.
YYZ
-
STL
2 stops26h 54m
Multiple Airlines
Deal found 18/3C$ 604
Thu 30/49:50 a.m.
STL
-
YYZ
2 stops11h 05m
Multiple Airlines
Thu 7/57:45 a.m.
YYZ
-
STL
1 stop17h 36m
Multiple Airlines
Deal found 16/3C$ 621
Tue 14/44:59 p.m.
STL
-
YYZ
2 stops26h 11m
Multiple Airlines
Sat 18/46:27 p.m.
YYZ
-
STL
1 stop6h 09m
Multiple Airlines
Deal found 15/3C$ 629
Wed 3/66:00 a.m.
STL
-
YUL
1 stop9h 53m
American Airlines
Tue 9/612:30 p.m.
YUL
-
STL
1 stop9h 00m
American Airlines
Deal found 17/3C$ 632

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 19 March 2026.

Round-trip from

C$ 476

One-way from

C$ 224

Popular in

November

Cheapest in

June

Average price

C$ 586

Good round-trip deal

C$ 325 or less
American Airlines
  • American Airlines
  • 14/4-21/4
  • 2 total stops
  • 29h 03m total
  • St. Louis to Ontario
Search Deals
7/5
  • 7/5
  • 2 total stops
  • 27h 40m total
  • St. Louis to Ontario
Search Deals
Highest demand for flights based on searches. 10% potential increase in price (C$ 111 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease (C$ 31 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in March 2026
Search Deals
Price to beat on a round-trip 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 629,999 searches. Data last updated 19 March 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

Mon 13/4

12:22 p.m.-6:43 a.m.

1 stop17h 21m

Toronto Pearson Intl

Thu 16/4

2:15 p.m.-8:44 p.m.

1 stop7h 29m

C$ 689

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Tue 21/4

7:45 a.m.-5:30 p.m.

1 stop8h 45m

Montreal Pierre Elliott Trudeau Intl

Sat 25/4

9:45 a.m.-9:52 p.m.

1 stop13h 07m

C$ 697

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Sat 2/5

7:05 a.m.-9:37 p.m.

2 stops13h 32m

Montreal Pierre Elliott Trudeau Intl

Sat 9/5

1:03 p.m.-11:56 p.m.

2 stops11h 53m

C$ 729

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Wed 22/7

6:00 a.m.-12:16 p.m.

1 stop5h 16m

Toronto Pearson Intl

Sun 26/7

6:15 a.m.-12:54 p.m.

1 stop7h 39m

C$ 743

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Mon 4/5

8:23 p.m.-2:13 p.m.

2 stops40h 50m

Montreal Pierre Elliott Trudeau Intl

Mon 11/5

6:51 p.m.-11:59 p.m.

1 stop6h 08m

C$ 743

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Mon 13/4

7:45 a.m.-1:42 p.m.

1 stop4h 57m

Toronto Pearson Intl

Wed 15/4

1:00 p.m.-7:31 p.m.

1 stop7h 31m

C$ 754

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Mon 4/5

1:05 p.m.-4:40 p.m.

Nonstop2h 35m

Montreal Pierre Elliott Trudeau Intl

Mon 11/5

6:30 p.m.-8:25 p.m.

Nonstop2h 55m

C$ 780

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Tue 14/4

6:48 a.m.-6:09 p.m.

2 stops10h 21m

Toronto Pearson Intl

Sat 18/4

10:00 a.m.-8:44 p.m.

2 stops11h 44m

C$ 853

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Thu 25/6

1:30 p.m.-11:56 p.m.

1 stop9h 26m

Montreal Pierre Elliott Trudeau Intl

Sat 4/7

2:30 p.m.-8:44 a.m.

1 stop19h 14m

C$ 862

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Mon 13/4

6:48 a.m.-6:09 p.m.

2 stops10h 21m

Toronto Pearson Intl

Fri 17/4

6:15 a.m.-11:56 a.m.

1 stop6h 41m

C$ 883

Flights are sorted by cheapest round-trip flights first.

Deals found on 15/3

Showing 1-10 of 40 resultsSorted by cheapest first
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2
3
4

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 C$ 243). Flying from St. Louis to Region of Ontario in January is currently the most expensive (average of C$ 1,072). 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 19 March 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 19 March 2026.

The most flights from STL to CAON are scheduled on a Monday (2 on average). You will have fewer flight options on Monday, which is when the least amount of flights are scheduled (2 on average).

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 19 March 2026.
See what other customers who have flown with Air Canada from St. Louis to Ontario have to say. Users can see the overall rating for each airline as well as how each is rated in terms of entertainment options, comfort, food, crew/service, and boarding process.
Air Canada
7.1
Good
10,818 reviews
Check prices

Crew

7.8

Entertainment

6.8

Overall

7.1

Comfort

7.1

Boarding

7.3

Food

6.3

Reviews

1 / 20
2.0
Mediocre

Anonymous,Feb 2026

YXE - YYZ

We were over three hours delayed leaving Saskatoon and missed our connection to Montreal. We were then rerouted all the way to Zurich. We were over seven hours late getting to our final destination. Then our luggage was lost for lost for three days. All three flights were delayed and our trip was definitely impacted.
Air Canada
7.1
Good
10,818 reviews
Air Canada
7.1
Good
10,818 reviews
Check prices

Crew

7.8

Entertainment

6.8

Overall

7.1

Comfort

7.1

Boarding

7.3

Food

6.3

Reviews

1 / 20
2.0
Mediocre

Anonymous,Feb 2026

YXE - YYZ

We were over three hours delayed leaving Saskatoon and missed our connection to Montreal. We were then rerouted all the way to Zurich. We were over seven hours late getting to our final destination. Then our luggage was lost for lost for three days. All three flights were delayed and our trip was definitely impacted.

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?

    If you book a flight to Ontario from St. Louis, you will be flying from Lambert-St Louis, which is the city’s only airport. Lambert-St Louis (STL) is located 20.4 km from the centre of St. Louis.

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

    Departing from St. Louis to Region of Ontario will take you 5h 16m. St. Louis and Region of Ontario are separated by a distance of 1051 km. Both multi-stop and direct flights can be found to your destination and back.

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

    The most popular flight routes from St. Louis to Region of Ontario are Lambert-St Louis - Montreal Pierre Elliott Trudeau Intl, Lambert-St Louis - Toronto Pearson Intl and Lambert-St Louis - London.

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

    Before booking your flight to Region of Ontario from St. Louis, check out the most reliable airlines to get you to your destination on time: United Airlines (72%), Air Canada (71%), Jazz( 71%).

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

    The cheapest flight price from St. Louis to Region of Ontario is C$ 325. On average you can expect to pay C$ 325. The most popular route, (Lambert-St Louis - Montreal Pierre Elliott Trudeau Intl), can usually be booked for C$ 562.

  • 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 C$ 243). Flying from St. Louis to Region of Ontario in January is currently the most expensive (average of C$ 1,072). 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

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Top airline flying from St. Louis to Ontario

Discover the top airline 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 629,999 searches. Data last updated 19 March 2026.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapestC$ 325AverageC$ 640FlexibilityNo cancel feeOn-time67%
Search Air Canada flights

Fly with Cheapflights

Find the best flight deals on Cheapflights, where travelers can enjoy low prices and a wide availability of flights to their desired destinations.

How does Cheapflights help users find flights from St. Louis to Ontario?

Cheapflights helps you search for flights from St. Louis to Ontario via 900+ travel sites so you don’t have to. After performing a flight search, users can also filter their flight selection by filtering for price, number of stops, airlines, and so on.

Why should you use Cheapflights to find cheap flight tickets from St. Louis to Ontario?

By finding flights from multiple airlines and providers at completely no cost, Cheapflights helps millions of users like you annually find the best flights to Ontario from St. Louis.

Can Cheapflights find flights from St. Louis to Ontario with no change fees?

Certainly. Search results for flights to Ontario from St. Louis shown to you on Cheapflights can be narrowed down with different useful search filters, which includes flexible booking options.

Can Cheapflights notify me if prices for flights from St. Louis to Ontario become cheaper?

Yes! Start tracking prices for St. Louis to Ontario flights today and get alerted whenever prices for these flights change. To access this feature, click the bell icon next to the flight deals above, which will prompt you for a valid email address to receive your alerts.

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