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Cheap flights from St. Louis to Ontario from C$ 284

STL — YYZ
9 Dec — 16 Dec1
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

Thu 26/116:09 p.m. -
1 stop18h 31m
Wed 9/1210:40 a.m. -
2 stops49h 37m
Deal found 5/11C$ 538
Thu 3/126:13 p.m. -
1 stop18h 27m
Thu 10/1212:20 p.m. -
2 stops23h 57m
Deal found 5/11C$ 545
Wed 2/1212:05 p.m. -
2 stops28h 05m
Sat 5/126:30 a.m. -
1 stop18h 42m
Deal found 5/11C$ 547
Sat 12/126:20 p.m. -
1 stop18h 20m
Sat 23/17:15 a.m. -
1 stop17h 49m
Deal found 4/11C$ 610
Wed 2/126:13 p.m. -
1 stop18h 27m
Wed 9/1210:40 a.m. -
2 stops49h 37m
Deal found 8/11C$ 672

Find flight deals from St. Louis to Ontario

Round-trip from

C$ 524

One-way from

C$ 284

Popular in

August

Cheapest in

January

Average price

C$ 896

Good round-trip deal

C$ 1,207 or less
10/2-17/2
  • 10/2-17/2
  • 3 total stops
  • 36h 12m total
  • St. Louis to Ontario
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10/12-31/12
  • 10/12-31/12
  • 1 total stop
  • 18h 20m total
  • St. Louis to Ontario
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Highest demand for flights based on searches. 14% potential increase in price (C$ 196 potential increase over avg. RT price).
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Cheapest flight prices on average. 2% potential price decrease (C$ 30 potential savings vs. average RT price).
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Average for round-trip flights in November 2026
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Price to beat on a round-trip flight from Lambert-St Louis to Ontario.
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Cheapflights Fare Finder

 
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 Lambert-St Louis - YYZ Toronto Pearson Intl

STLYYZ

Lambert-St Louis

Wed 9/12

12:02 p.m.-3:20 p.m.

2 stops26h 18m

Toronto Pearson Intl

Wed 31/12

12:00 a.m.-11:00 p.m.

Nonstop0h 00m

C$ 304

St. LouisToronto

STL Lambert-St Louis - YYZ Toronto Pearson Intl

STLYYZ

Lambert-St Louis

Sun 20/12

5:58 p.m.-1:40 p.m.

1 stop18h 42m

Toronto Pearson Intl

Wed 31/12

12:00 a.m.-11:00 p.m.

Nonstop0h 00m

C$ 340

St. LouisToronto

STL Lambert-St Louis - YYZ Toronto Pearson Intl

STLYYZ

Lambert-St Louis

Wed 18/11

4:18 p.m.-12:55 a.m.

3 stops31h 37m

Toronto Pearson Intl

Wed 31/12

12:00 a.m.-11:00 p.m.

Nonstop0h 00m

C$ 357

St. LouisToronto

STL Lambert-St Louis - YYZ Toronto Pearson Intl

STLYYZ

Lambert-St Louis

Fri 11/12

5:02 a.m.-2:42 p.m.

1 stop8h 40m

Toronto Pearson Intl

Wed 31/12

12:00 a.m.-11:00 p.m.

Nonstop0h 00m

C$ 360

St. LouisToronto

STL Lambert-St Louis - YYZ Toronto Pearson Intl

STLYYZ

Lambert-St Louis

Thu 10/12

6:20 p.m.-11:47 p.m.

3 stops28h 27m

Toronto Pearson Intl

Wed 31/12

12:00 a.m.-11:00 p.m.

Nonstop0h 00m

C$ 372

St. LouisToronto

STL Lambert-St Louis - YYZ Toronto Pearson Intl

STLYYZ

Lambert-St Louis

Thu 24/12

5:58 p.m.-1:40 p.m.

1 stop18h 42m

Toronto Pearson Intl

Wed 31/12

12:00 a.m.-11:00 p.m.

Nonstop0h 00m

C$ 379

St. LouisToronto

STL Lambert-St Louis - YYZ Toronto Pearson Intl

STLYYZ

Lambert-St Louis

Mon 28/12

6:21 p.m.-9:55 p.m.

2 stops26h 34m

Toronto Pearson Intl

Wed 31/12

12:00 a.m.-11:00 p.m.

Nonstop0h 00m

C$ 431

St. LouisToronto

STL Lambert-St Louis - YYZ Toronto Pearson Intl

STLYYZ

Lambert-St Louis

Sat 28/11

5:15 p.m.-1:40 p.m.

2 stops19h 25m

Toronto Pearson Intl

Wed 31/12

12:00 a.m.-11:00 p.m.

Nonstop0h 00m

C$ 500

St. LouisToronto

STL Lambert-St Louis - YYZ Toronto Pearson Intl

STLYYZ

Lambert-St Louis

Sat 5/12

6:30 a.m.-4:47 p.m.

1 stop9h 17m

Toronto Pearson Intl

Tue 8/12

4:30 p.m.-10:59 p.m.

1 stop7h 29m

C$ 996

St. LouisToronto

STL Lambert-St Louis - YYZ Toronto Pearson Intl

STLYYZ

Lambert-St Louis

Thu 3/12

2:02 p.m.-1:40 p.m.

2 stops22h 38m

Toronto Pearson Intl

Mon 7/12

7:35 a.m.-12:12 a.m.

3 stops17h 37m

C$ 1,066

Flights are sorted by cheapest round-trip flights first.

Deals found on 8/11

Showing 1-10 of 20 resultsSorted by cheapest first
1
2

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

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, March is the cheapest month in which you can book a flight from St. Louis to Region of Ontario (average of C$ 600). Flying from St. Louis to Region of Ontario in January is currently the most expensive (average of C$ 1,003). 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?

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.

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

Airfare is typical for this route at the moment.
St. Louis to Region of Ontario flights typically cost between C$ 469 and C$ 677 in February.
The cheapest round-trip price found within the last 5 days was C$ 524 on Multiple Airlines (10 Feb-17 Feb).

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 87 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

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
11,874 reviews
Check prices

Overall

7.1

Food

6.4

Comfort

7.1

Entertainment

6.8

Boarding

7.3

Crew

7.8

Reviews

1 / 20
2.0
Mediocre

Shawna,Sep 2025

DCA - YYZ

Business class cabin was *freezing*. Landing was so hard it injured my back - no apology or explanation given
Air Canada
7.1
Good
11,874 reviews
Air Canada
7.1
Good
11,874 reviews
Check prices

Overall

7.1

Food

6.4

Comfort

7.1

Entertainment

6.8

Boarding

7.3

Crew

7.8

Reviews

1 / 20
2.0
Mediocre

Shawna,Sep 2025

DCA - YYZ

Business class cabin was *freezing*. Landing was so hard it injured my back - no apology or explanation given

Related info for your journey

  • 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 9h 17m. 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: United Airlines (84%), Air Canada (79%), Jazz( 79%).

  • 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$ 230. On average you can expect to pay C$ 1,210. The most popular route, (Lambert-St Louis - Toronto Pearson Intl), can usually be booked for C$ 540.

  • 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, March is the cheapest month in which you can book a flight from St. Louis to Region of Ontario (average of C$ 600). Flying from St. Louis to Region of Ontario in January is currently the most expensive (average of C$ 1,003). 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

Top airline flying from St. Louis to Ontario

AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapestC$ 334AverageC$ 809FlexibilityNo cancel feeOn-time67%
Search Air Canada flights

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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.

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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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