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Cheap flights from St. Louis to Ontario from C$ 128

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 24/2. Fares are subject to change and may not be available on all flights or dates of travel.
STL — YYZ
28 Feb — 7 Mar1
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 29 January 2026.

Wed 25/23:49 p.m.
STL
-
YYZ
1 stop18h 37m
Multiple Airlines
Wed 4/37:15 a.m.
YYZ
-
STL
1 stop16h 12m
Multiple Airlines
Deal found 28/1C$ 296
Wed 18/23:49 p.m.
STL
-
YYZ
1 stop7h 25m
Multiple Airlines
Fri 20/27:10 a.m.
YYZ
-
STL
1 stop18h 17m
Multiple Airlines
Deal found 27/1C$ 353
Sat 28/22:51 p.m.
STL
-
YYZ
2 stops38h 52m
Multiple Airlines
Wed 4/38:20 p.m.
YYZ
-
STL
1 stop28h 39m
Multiple Airlines
Deal found 27/1C$ 362
Tue 3/33:49 p.m.
STL
-
YYZ
1 stop7h 25m
Multiple Airlines
Tue 17/37:10 a.m.
YYZ
-
STL
1 stop17h 09m
Multiple Airlines
Deal found 27/1C$ 371
Fri 27/23:49 p.m.
STL
-
YYZ
2 stops26h 45m
Multiple Airlines
Tue 3/37:15 a.m.
YYZ
-
STL
1 stop16h 12m
Multiple Airlines
Deal found 27/1C$ 400
Tue 7/44:54 p.m.
STL
-
YYZ
1 stop30h 20m
Multiple Airlines
Tue 14/43:40 p.m.
YYZ
-
STL
2 stops16h 10m
Multiple Airlines
Deal found 27/1C$ 406
Fri 27/23:49 p.m.
STL
-
YYZ
2 stops26h 45m
Multiple Airlines
Wed 4/37:15 a.m.
YYZ
-
STL
1 stop16h 12m
Multiple Airlines
Deal found 27/1C$ 443
Mon 13/48:41 a.m.
STL
-
YYZ
1 stop14h 33m
Multiple Airlines
Tue 14/47:15 a.m.
YYZ
-
STL
1 stop17h 04m
Multiple Airlines
Deal found 27/1C$ 456
Tue 7/44:46 p.m.
STL
-
YUL
1 stop17h 58m
American Airlines
Thu 9/412:30 p.m.
YUL
-
STL
1 stop10h 44m
American Airlines
Deal found 28/1C$ 466
Tue 17/26:00 a.m.
STL
-
YUL
1 stop8h 04m
American Airlines
Fri 20/23:45 p.m.
YUL
-
STL
1 stop19h 28m
American Airlines
Deal found 26/1C$ 500
Fri 3/48:24 a.m.
STL
-
YUL
1 stop15h 06m
Multiple Airlines
Mon 6/45:10 p.m.
YUL
-
STL
2 stops31h 15m
Multiple Airlines
Deal found 27/1C$ 573
Wed 22/44:55 p.m.
STL
-
YUL
1 stop30h 35m
Multiple Airlines
Sun 26/45:10 p.m.
YUL
-
STL
2 stops14h 40m
Multiple Airlines
Deal found 26/1C$ 593

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 29 January 2026.

Round-trip from

C$ 296

One-way from

C$ 128

Popular in

November

Cheapest in

June

Average price

C$ 722
25/2-4/3
  • 25/2-4/3
  • 2 total stops
  • 34h 49m total
  • St. Louis to Ontario
Search Deals
24/2
  • 24/2
  • 1 total stop
  • 7h 25m total
  • St. Louis to Ontario
Search Deals
Highest demand for flights based on searches. 10% potential increase in price (C$ 107 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease (C$ 29 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in January 2026
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 29 January 2026.
Use the filters below to find and compare flights from St. Louis to Ontario that are best for you.

Fly from

St. Louis

Fly to

Ontario

Route

Depart

Return

Price

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Tue 3/3

3:49 p.m.-12:14 a.m.

1 stop7h 25m

Toronto Pearson Intl

Tue 17/3

7:10 a.m.-11:19 p.m.

1 stop17h 09m

C$ 371

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Mon 13/4

8:41 a.m.-12:14 a.m.

1 stop14h 33m

Toronto Pearson Intl

Tue 14/4

3:40 p.m.-6:50 a.m.

2 stops16h 10m

C$ 452

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Tue 7/4

4:46 p.m.-11:44 a.m.

1 stop17h 58m

Montreal Pierre Elliott Trudeau Intl

Thu 9/4

12:30 p.m.-10:14 p.m.

1 stop10h 44m

C$ 466

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sat 11/4

6:00 a.m.-2:34 p.m.

1 stop7h 34m

Toronto Pearson Intl

Wed 15/4

6:15 a.m.-6:27 p.m.

1 stop13h 12m

C$ 490

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Thu 26/2

3:49 p.m.-12:14 a.m.

1 stop7h 25m

Toronto Pearson Intl

Wed 4/3

7:15 a.m.-10:27 p.m.

1 stop16h 12m

C$ 527

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sun 12/4

11:21 a.m.-2:53 p.m.

2 stops26h 32m

Toronto Pearson Intl

Thu 16/4

7:15 a.m.-11:19 p.m.

1 stop17h 04m

C$ 582

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Wed 22/4

4:55 p.m.-12:30 a.m.

1 stop30h 35m

Montreal Pierre Elliott Trudeau Intl

Sun 26/4

5:10 p.m.-6:50 a.m.

2 stops14h 40m

C$ 593

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sat 28/2

3:49 p.m.-12:14 a.m.

1 stop7h 25m

Toronto Pearson Intl

Mon 2/3

7:15 a.m.-11:59 p.m.

1 stop17h 44m

C$ 604

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Fri 20/2

5:50 p.m.-10:40 p.m.

1 stop3h 50m

Toronto Pearson Intl

Mon 23/2

3:40 p.m.-6:51 a.m.

2 stops40h 11m

C$ 611

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Thu 12/2

3:49 p.m.-12:14 a.m.

1 stop7h 25m

Toronto Pearson Intl

Sun 15/2

3:40 p.m.-6:51 a.m.

2 stops16h 11m

C$ 612

Flights are sorted by cheapest round-trip flights first.

Deals found on 27/1

Showing 1-10 of 44 results
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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 C$ 242). Flying from St. Louis to Region of Ontario in January is currently the most expensive (average of C$ 1,060). 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 29 January 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 29 January 2026.

The most flights from STL to CAON are scheduled on a Tuesday (2 on average). You will have fewer flight options on Monday, which is when the least amount of flights are scheduled (1 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 29 January 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
10,667 reviews
Check prices

Crew

7.8

Boarding

7.3

Comfort

7.1

Entertainment

6.8

Food

6.3

Overall

7.1

Reviews

1 / 20
4.0
Okay

Sugith,Jan 2026

YSB - YYZ

Left 2 hours late. Stuck on plane for an hour after boarding before take off.
Air Canada
7.1
Good
10,667 reviews
Air Canada
7.1
Good
10,667 reviews
Check prices

Crew

7.8

Boarding

7.3

Comfort

7.1

Entertainment

6.8

Food

6.3

Overall

7.1

Reviews

1 / 20
4.0
Okay

Sugith,Jan 2026

YSB - YYZ

Left 2 hours late. Stuck on plane for an hour after boarding before take off.

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 17h 58m. St. Louis and Region of Ontario are separated by a distance of 1556 km.

  • 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 (72%), Jazz (72%), United Airlines( 72%).

  • 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$ 242). Flying from St. Louis to Region of Ontario in January is currently the most expensive (average of C$ 1,060). 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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Alternative routes for St. Louis to Ontario

See prices for flight routes from nearby airports that may be better suited for you.
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Kansas City to Calgary flights
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Kansas City to Québec City flights
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Kansas City to Halifax flights
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Joplin to Pierre Elliott Trudeau Intl flights
St. Louis to Charlottetown flights
Kansas City to Victoria flights
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Kansas City to Moncton flights
Kansas City to Saskatoon flights

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 29 January 2026.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapestC$ 296AverageC$ 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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