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Cheap flights from Ottawa to St. Louis from C$ 653

This is the cheapest round-trip flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 1/10. Fares are subject to change and may not be available on all flights or dates of travel.
YOW — STL
11 Oct — 18 Oct1
1 adult
1 adult, Economy

Cheap flight deals from Ottawa to St. Louis

Discover tips and strategies to find the most affordable flight options for your journey from Ottawa (YOW) to St. Louis (STL). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated 11 September 2025.

Round-trip from

C$ 653

Popular in

December

Cheapest in

September

Average price

C$ 716
1/10-8/10
  • 1/10-8/10
  • 3 total stops
  • 35h 57m total
  • Ottawa to St. Louis
Search Deals
Highest demand for flights based on searches. 6% potential increase in price (C$ 80 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 1% potential price decrease (C$ 19 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in September 2025
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Find flight deals from Ottawa to St. Louis

Cheapest flights from Ottawa to St. Louis
Explore the most affordable flight options available from Ottawa to St. Louis. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 11 September 2025.

Wed 1/103:50 p.m.YOW - STL
1 stop18h 50mMultiple Airlines
Wed 8/106:33 a.m.STL - YOW
2 stops17h 07mMultiple Airlines
Deal found 11/9C$ 653
Fri 10/103:50 p.m.YOW - STL
1 stop27h 20mMultiple Airlines
Tue 14/107:52 p.m.STL - YOW
2 stops20h 05mMultiple Airlines
Deal found 10/9C$ 693
Wed 1/105:25 p.m.YOW - STL
1 stop18h 24mUnited Airlines
Wed 8/105:00 a.m.STL - YOW
1 stop8h 04mUnited Airlines
Deal found 11/9C$ 750
Fri 10/1011:55 a.m.YOW - STL
1 stop4h 23mAir Canada
Tue 14/109:15 a.m.STL - YOW
1 stop6h 49mAir Canada
Deal found 9/9C$ 804
Fri 10/107:29 p.m.YOW - STL
2 stops17h 59mUnited Airlines
Tue 14/105:28 p.m.STL - YOW
2 stops20h 36mUnited Airlines
Deal found 10/9C$ 843
Sat 13/93:50 p.m.YOW - STL
1 stop18h 50mMultiple Airlines
Sun 14/91:52 p.m.STL - YOW
2 stops26h 28mMultiple Airlines
Deal found 11/9C$ 1,063

Cheapflights Fare Finder

 
Customize your flight search to find flights from Ottawa to St. Louis 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 11 September 2025.
Use the filters below to find and compare flights from Ottawa to St. Louis that are best for you.

Fly from

Ottawa

Fly to

St. Louis

Route

Depart

Return

Price

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Fri 10/10

3:50 p.m.-6:10 p.m.

1 stop27h 20m

Lambert-St Louis

Tue 14/10

7:52 p.m.-4:57 p.m.

2 stops20h 05m

C$ 693

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Wed 1/10

5:25 p.m.-10:49 a.m.

1 stop18h 24m

Lambert-St Louis

Wed 8/10

5:00 a.m.-2:04 p.m.

1 stop8h 04m

C$ 750

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Fri 10/10

11:55 a.m.-3:18 p.m.

1 stop4h 23m

Lambert-St Louis

Tue 14/10

9:15 a.m.-5:04 p.m.

1 stop6h 49m

C$ 804

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Tue 3/3

10:35 a.m.-3:21 p.m.

1 stop5h 46m

Lambert-St Louis

Wed 4/3

3:15 p.m.-9:14 p.m.

1 stop4h 59m

C$ 818

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Fri 10/10

7:29 p.m.-12:28 p.m.

2 stops17h 59m

Lambert-St Louis

Tue 14/10

5:28 p.m.-3:04 p.m.

2 stops20h 36m

C$ 843

Flights are sorted by cheapest round-trip flights first.

Deals found on 10/9

Best time to book a flight from Ottawa to St. Louis

Have a flexible travel schedule? Discover the best time to fly to St. Louis from Ottawa 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 Ottawa to St. Louis

What is the cheapest month to book a flight from Ottawa to St. Louis?

Currently, January is the cheapest month in which you can book a flight from Ottawa to St. Louis (average of C$ 365). Flying from Ottawa to St. Louis in September is currently the most expensive (average of C$ 491). 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.

How much does it cost to fly round-trip from Ottawa to St. Louis?

Reviews of airlines servicing St. Louis

Get insights into the airlines that provide service to St. Louis. 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 St. Louis. Reviews last updated 11 September 2025.
Check out reviews from past customers who have flown with United Airlines and Air Canada from Ottawa to St. Louis to help guide your decision. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
United Airlines
7.4
Good
8,937 reviews
Check prices

Crew

8.1

Boarding

7.7

Entertainment

7.1

Overall

7.4

Food

6.6

Comfort

7.3

Reviews

1 / 20
10.0
Excellent

Anonymous,Sep 2025

FRA - SFO

Lufthansa was amazing, I wish United States based airlines operated like them.
United Airlines
7.4
Good
8,937 reviews
United Airlines
7.4
Good
8,937 reviews
Check prices

Crew

8.1

Boarding

7.7

Entertainment

7.1

Overall

7.4

Food

6.6

Comfort

7.3

Reviews

1 / 20
10.0
Excellent

Anonymous,Sep 2025

FRA - SFO

Lufthansa was amazing, I wish United States based airlines operated like them.
Air Canada
7.1
Good
10,000 reviews
United Airlines
7.4
Good
8,937 reviews
Check prices

Crew

8.1

Boarding

7.7

Entertainment

7.1

Overall

7.4

Food

6.6

Comfort

7.3

Reviews

1 / 20
10.0
Excellent

Anonymous,Sep 2025

FRA - SFO

Lufthansa was amazing, I wish United States based airlines operated like them.

Related info for your journey

Find useful and relevant information for your journey from Ottawa to St. Louis. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • How long is the flight from Ottawa to St. Louis?

    There are many flights that can get you from Ottawa to St. Louis in 4h 23m. Fly via United Airlines or Air Canada to get the fastest option. Airlines will cover a distance of 1413 km. When browsing for deals, the options you’ll see will be for both direct flights and flights with stops.

  • What are the cheapest airlines flying from Ottawa to St. Louis round-trip?

    United Airlines, at C$ 322, was found to be the cheapest airline from Ottawa to St. Louis. An alternate airline flying to your destination would be Air Canada. United Airlines is currently priced 63% below the average price you’ll pay for this route.

  • Can I find deals for flights from Ottawa to St. Louis that include hotel bookings?

    Yes. In addition to deals on Ottawa to St. Louis flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Ottawa to St. Louis?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Ottawa to St. Louis.

  • Can I find deals for business class flights from Ottawa to St. Louis?

    Yes. Cheapflights offers flight deals from Ottawa to St. Louis 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 Ottawa to St. Louis?

    Currently, January is the cheapest month in which you can book a flight from Ottawa to St. Louis (average of C$ 365). Flying from Ottawa to St. Louis in September is currently the most expensive (average of C$ 491). 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

Travelling to a place near St. Louis?

Book flights to St. Louis if you plan to visit one of these locations
Chesterfield
St. Peters

Browse thousands of different options on Cheapflights for your next trip

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Top 2 airlines flying from Ottawa to St. Louis

Discover the top 2 airlines that operate flights from Ottawa to St. Louis. 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 11 September 2025.
AirlineCheapestAverageFlexibilityOn-time
United AirlinesCheapestC$ 322AverageC$ 954FlexibilityNo cancel feeOn-time69%
Search United Airlines flights
Air CanadaCheapestC$ 762AverageC$ 874FlexibilityNo cancel feeOn-time67%
Search Air Canada flights

Fly with Cheapflights

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

When you search for this flight from Ottawa to St. Louis, Cheapflights searches on 900+ travel sites to save you time finding great flight deals online. Additionally, we offer filter features so you can choose a preferred cabin class or airline, see different price ranges, and much more so you can book the flight for you.

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

Cheapflights helps you find that perfect flight to St. Louis from Ottawa by searching from hundreds of airlines and agencies you know and love. We are also free to use, in case you were wondering!

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

Users can book flights with no change fees policies with our dedicated filters. Book flights from Ottawa to St. Louis flexibly with Cheapflights today.

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

Yes! Start tracking prices for Ottawa to St. Louis 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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