CA $221 Cheap Flights from Ontario (ONT) to St. Louis (STL)

View CA $221 flight on Sat, Oct. 11, 2025Opens in a new window

Popular airlines from Los Angeles - Ontario Intl. Airport (ONT) to Lambert-St. Louis International Airport (STL)

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Cheap flights from Ontario (ONT) to St. Louis (STL)

Prices were available within the past 7 days and start at CA $221 for one-way flights and for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Find the cheapest month to fly from Ontario (ONT) to St. Louis (STL)

October is typically the cheapest month to fly

From CA $163 - CA $557 per traveller.

Graph displaying average flight prices per month

Flight from Ontario to St. Louis (ONT - STL) route information
Origin airport
Los Angeles - Ontario Intl.
Destination airport
Lambert-St. Louis Intl.
Distance
2467 km
Average flight time
5 hours 15 mins

Los Angeles to St. Louis Flights

The easy way to book your flights from Ontario to St. Louis 

With Expedia, it’s simple to find and book flights to St. Louis from Ontario whether you’re traveling for business or pleasure. Enter your travel dates, hit search, and choose your flight from 18 airlines that cover this route. There are Southwest Airlines nonstop flights to Lambert-St. Louis Intl., too.  

Choose your preferred carrier and cabin class with the advanced search tool and select your ideal departure time. Then, if you want, you can see just nonstop or refundable flights. And if you’re traveling last minute, just enter the date to check out flights from Ontario to St. Louis today, tomorrow, or this week.  

 

Save dollars with cheap flights from Los Angeles - Ontario Intl., ONT to Lambert-St. Louis Intl., STL 

Sort your search results by price to find great deals on your flight from Ontario to St. Louis—you get all your cheapest options first. Grab yourself a bargain now—the lowest price on flights to St. Louis from Ontario currently is just rising to .  

Here are more money-saving tips: 

  • Fly in when flight prices are normally at their lowest 
  • Book about a month to 6 weeks before you travel for the best prices to St. Louis  
  • Avoid peak season and weekends when flights can cost more
  • Early morning and late-night flights are sometimes cheaper, so try varying your travel times 
  • One surefire way to save money on your flight is to book your flight and hotel together with Expedia. Sometimes, the savings are so large that the flight is basically free! 

 

Reasons to choose Expedia for your flight to St. Louis from Ontario 

Whatever your destination, budget, or reason to travel, in just one quick search, you can choose from loads of flights, airlines, and cabin classes. The filters make it quick and easy to find your ideal flights, and if you choose one of the flexible options, you won’t be charged to change your flight. So book your flight to St. Louis with Expedia today.

Frequently asked questions

How much is a flight from ONT to Lambert-St. Louis Intl. Airport (STL)?
Round-trip tickets from Los Angeles - Ontario Intl. Airport (ONT) to STL start from . This figure is based on fares offered within the last 7 days on Expedia for flights departing within the next year — book ASAP so you don't miss out. Prices and availability are subject to change. Additional terms apply.
Do I need to pay a cancellation fee if I cancel my flight from Ontario Airport to Lambert-St. Louis Intl. Airport (STL)?
This varies from airline to airline, as each one has its own terms and conditions. Head to the Customer Service Portal, where there are simple instructions on how to cancel your flight online.
How do I find cheap flights from ONT to Lambert Field that have flexible change policies?
Many carriers will allow you to reschedule your flight at no extra charge. All you pay is the fare difference. When searching for ONT to Lambert Field flights, you'll find a "No change fees" filter for you to pick.
How many hours is the flight from ONT to Lambert Field?
The average flight time between Los Angeles - Ontario Intl. Airport (ONT) and STL is 4 hours and 51 minutes. If you're travelling with kids, it's always a good idea to pack some fruit or snacks in your carry-on luggage.
How far is the flight from ONT to STL?
The flight distance between Los Angeles - Ontario Intl. Airport (ONT) and STL is 2,500 kilometres. Pack yourself a drink, a few snacks and a few good podcasts. Keep yourself entertained and time will zip by.
Which airlines fly direct from ONT to Lambert Field?
Flying nonstop between ONT and Lambert-St. Louis Intl. Airport (STL) isn't possible right now. However, you'll still be able to find a flight to St. Louis with at least one stop.
Are Ontario Airport to STL flight tickets cheaper when they're purchased at the last minute?
Booking your trip from Los Angeles - Ontario Intl. Airport (ONT) to Lambert Field at the last minute could be your ticket to a fantastic deal. However, it could end up costing a great deal more! If you'd prefer not to take the risk, book well ahead of your departure date. In fact, Expedia has some of the biggest bargains up to 12 months in advance. If your preferred air carrier hasn't released tickets yet, check back often as deals are updated all the time on Expedia.

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Ontario nearby Airports

Los Angeles

Los Angeles Intl. to St. Louis
CA $433.68
*Available to Expedia members.