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Cheap flights from St. Louis to Ontario from C$ 188

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 12/6. Fares are subject to change and may not be available on all flights or dates of travel.
STL — YYZ
3 Jun — 10 Jun1
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 4 May 2026.

Wed 27/55:27 p.m.
STL
-
YYZ
2 stops19h 38m
Multiple Airlines
Wed 3/69:50 a.m.
YYZ
-
STL
1 stop15h 07m
Multiple Airlines
Deal found 1/5C$ 480
Wed 27/52:36 p.m.
STL
-
YYZ
1 stop7h 48m
American Airlines
Wed 3/611:39 a.m.
YYZ
-
STL
1 stop8h 41m
American Airlines
Deal found 1/5C$ 510
Wed 17/67:03 a.m.
STL
-
YYZ
1 stop9h 41m
American Airlines
Wed 24/67:25 a.m.
YYZ
-
STL
1 stop10h 08m
American Airlines
Deal found 30/4C$ 511
Sat 6/65:27 p.m.
STL
-
YYZ
2 stops19h 38m
Multiple Airlines
Wed 10/69:50 a.m.
YYZ
-
STL
1 stop14h 59m
Multiple Airlines
Deal found 1/5C$ 523
Sun 28/64:17 p.m.
STL
-
YYZ
1 stop26h 48m
Multiple Airlines
Sun 5/74:45 p.m.
YYZ
-
STL
2 stops26h 51m
Multiple Airlines
Deal found 2/5C$ 529
Wed 27/55:27 p.m.
STL
-
YYZ
2 stops19h 38m
Multiple Airlines
Sat 30/57:45 a.m.
YYZ
-
STL
1 stop17h 12m
Multiple Airlines
Deal found 29/4C$ 537
Tue 2/66:33 p.m.
STL
-
YYZ
2 stops21h 22m
Multiple Airlines
Mon 8/67:45 a.m.
YYZ
-
STL
1 stop17h 12m
Multiple Airlines
Deal found 3/5C$ 538
Tue 23/62:32 p.m.
STL
-
YYZ
1 stop7h 57m
American Airlines
Tue 30/67:25 a.m.
YYZ
-
STL
1 stop7h 37m
American Airlines
Deal found 30/4C$ 539
Tue 9/64:17 p.m.
STL
-
YYZ
1 stop26h 48m
Multiple Airlines
Fri 12/69:50 a.m.
YYZ
-
STL
1 stop14h 59m
Multiple Airlines
Deal found 29/4C$ 542
Wed 3/64:19 p.m.
STL
-
YYZ
1 stop23h 26m
Multiple Airlines
Mon 8/610:25 p.m.
YYZ
-
STL
2 stops21h 58m
Multiple Airlines
Deal found 3/5C$ 546
Wed 27/51:45 p.m.
STL
-
YYZ
1 stop8h 39m
American Airlines
Sat 30/57:20 a.m.
YYZ
-
STL
1 stop10h 24m
American Airlines
Deal found 30/4C$ 548
Sat 13/61:05 p.m.
STL
-
YUL
Nonstop2h 35m
Air Canada
Sat 20/68:10 a.m.
YUL
-
STL
1 stop5h 11m
Air Canada
Deal found 29/4C$ 610

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 4 May 2026.

Round-trip from

C$ 480

One-way from

C$ 188

Popular in

November

Cheapest in

June

Average price

C$ 663

Good round-trip deal

C$ 283 or less
27/5-3/6
  • 27/5-3/6
  • 3 total stops
  • 34h 45m total
  • St. Louis to Ontario
Search Deals
12/6
  • 12/6
  • 2 total stops
  • 19h 59m total
  • St. Louis to Ontario
Search Deals
Highest demand for flights based on searches. 4% potential increase in price (C$ 42 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease (C$ 22 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in May 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 4 May 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 15/6

1:05 p.m.-9:58 p.m.

1 stop7h 53m

Toronto Pearson Intl

Mon 22/6

12:05 p.m.-8:25 p.m.

2 stops9h 20m

C$ 609
Quickest round-trip

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sat 23/5

5:36 p.m.-11:14 p.m.

1 stop4h 38m

Toronto Pearson Intl

Tue 26/5

7:22 p.m.-11:21 p.m.

1 stop4h 59m

C$ 734

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Wed 3/6

6:00 a.m.-4:10 p.m.

1 stop9h 10m

Montreal Pierre Elliott Trudeau Intl

Fri 5/6

4:55 p.m.-9:16 p.m.

1 stop5h 21m

C$ 735

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sun 23/8

5:32 p.m.-11:59 p.m.

1 stop5h 27m

Toronto Pearson Intl

Thu 27/8

7:00 a.m.-12:49 p.m.

1 stop6h 49m

C$ 742

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sat 30/5

1:13 p.m.-11:18 p.m.

1 stop9h 05m

Toronto Pearson Intl

Wed 3/6

4:00 p.m.-11:29 p.m.

1 stop8h 29m

C$ 743

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Sun 12/7

6:01 a.m.-1:09 p.m.

1 stop6h 08m

Montreal Pierre Elliott Trudeau Intl

Fri 17/7

9:45 a.m.-3:46 p.m.

1 stop7h 01m

C$ 750

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Fri 10/7

6:06 a.m.-5:15 p.m.

1 stop10h 09m

Toronto Pearson Intl

Mon 13/7

6:02 p.m.-11:32 p.m.

1 stop6h 30m

C$ 764

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Fri 30/10

6:03 a.m.-2:44 p.m.

1 stop7h 41m

Toronto Pearson Intl

Mon 2/11

5:18 p.m.-9:42 p.m.

1 stop5h 24m

C$ 764

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Tue 21/7

1:13 p.m.-7:37 p.m.

1 stop5h 24m

Toronto Pearson Intl

Tue 28/7

10:15 a.m.-3:46 p.m.

1 stop6h 31m

C$ 764

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Fri 30/10

1:27 p.m.-9:34 p.m.

1 stop7h 07m

Toronto Pearson Intl

Mon 2/11

10:45 a.m.-4:40 p.m.

1 stop6h 55m

C$ 764

Flights are sorted by cheapest round-trip flights first.

Deals found on 2/5

Showing 1-10 of 46 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

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.

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$ 189). Flying from St. Louis to Region of Ontario in January is currently the most expensive (average of C$ 636). 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 4 May 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 4 May 2026.

The most flights from STL to CAON are scheduled on a Monday (4 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (2 on average).

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 4 May 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
10,995 reviews
Check prices

Food

6.3

Entertainment

6.8

Overall

7.1

Comfort

7.1

Crew

7.8

Boarding

7.3

Reviews

1 / 20
8.0
Excellent

John,Apr 2026

YVR - YOW

Crew was very attentive and meals were good. My wife required a wheel chair due to an accident on vacation. The service in Toronto was poor and Ottawa no better. Southeast Asia could teach them lots. Flight originated in Manila on ANA which was cancelled due to a mechanical issue. We were put up overnight in the Savoy Hotel with dinner and breakfast. The airline staff and hotel staff were fantastic.
Air Canada
7.1
Good
10,995 reviews
Air Canada
7.1
Good
10,995 reviews
Check prices

Food

6.3

Entertainment

6.8

Overall

7.1

Comfort

7.1

Crew

7.8

Boarding

7.3

Reviews

1 / 20
8.0
Excellent

John,Apr 2026

YVR - YOW

Crew was very attentive and meals were good. My wife required a wheel chair due to an accident on vacation. The service in Toronto was poor and Ottawa no better. Southeast Asia could teach them lots. Flight originated in Manila on ANA which was cancelled due to a mechanical issue. We were put up overnight in the Savoy Hotel with dinner and breakfast. The airline staff and hotel staff were fantastic.

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 4h 38m. 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 - Toronto Pearson Intl, Lambert-St Louis - Montreal Pierre Elliott Trudeau 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: Air Canada (78%), Jazz (78%), United Airlines( 78%).

  • 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$ 279. On average you can expect to pay C$ 823. The most popular route, (Lambert-St Louis - Toronto Pearson Intl), can usually be booked for C$ 480.

  • 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$ 189). Flying from St. Louis to Region of Ontario in January is currently the most expensive (average of C$ 636). 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 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 4 May 2026.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapestC$ 322AverageC$ 633FlexibilityNo 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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