CA $287 Cheap Flights from St. Louis (STL) to Ontario (ONT)

View CA $287 flight on Sun, Dec. 21, 2025Opens in a new window

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

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

Prices were available within the past 7 days and start at CA $287 for one-way flights and for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Flight from St. Louis to Ontario (STL - ONT) route information
Origin airport
Lambert-St. Louis Intl.
Destination airport
Los Angeles - Ontario Intl.
Distance
2467 km
Average flight time
3 hours 10 mins

St. Louis to Los Angeles Flights

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

With Expedia, it’s simple to find and book flights to Ontario from St. Louis whether you’re traveling for business or pleasure. Enter your travel dates, hit search, and choose your flight from 1 airlines that cover this route. There are Southwest Airlines nonstop flights to Los Angeles - Ontario 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 St. Louis to Ontario today, tomorrow, or this week.  

 

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

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

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 Ontario with Expedia today.

Frequently asked questions

How much is a flight from Lambert-St. Louis Intl. Airport (STL) to ONT?
Based on fares advertised within the last 7 days on Expedia for flights departing within the next year, round-trip flights between STL and ONT start from . Book ASAP to get the best price for your next big adventure. Prices and availability are subject to change. Additional terms apply.
Do I need to pay a cancellation fee if I cancel my flight from Lambert-St. Louis Intl. Airport (STL) to Los Angeles - Ontario Intl. Airport (ONT)?
Most flights can be cancelled online, but whether or not you incur a fee all comes down to your airline. If you do need to cancel your trip, follow the instructions in the Customer Service Portal.
How do I find cheap flights from Lambert Field to Ontario Airport that have flexible change policies?
Select our "No change fees" filter to find flexible travel options for your flight from Lambert-St. Louis Intl. Airport (STL) to Ontario Airport. This allows you to secure a great deal in advance and still have the freedom to reschedule without any additional fees. Just keep in mind that fare differences may still apply.
How many hours is the flight from Lambert-St. Louis Intl. Airport (STL) to Ontario Airport?
The flight time from Lambert Field to Ontario Airport is roughly 5 hours and 34 minutes. Put on your earphones, listen to a gripping podcast and the time will fly by.
How far is the flight from STL to Ontario Airport?
The flight distance from Lambert-St. Louis Intl. Airport (STL) to Los Angeles - Ontario Intl. Airport (ONT) is 2,500 kilometres. Pack yourself a snack, a drink and a good book to read. Keep yourself entertained and the hours will fly by.
Which airlines fly direct from Lambert-St. Louis Intl. Airport (STL) to ONT?
Flying nonstop between STL and ONT isn't possible right now. However, you'll still be able to find a flight to Ontario with at least one stop.
Are Lambert-St. Louis Intl. Airport (STL) to ONT flight tickets cheaper when they're purchased at the last minute?
Booking your trip from Lambert Field to Ontario Airport at the last minute could be your ticket to a great deal. However, it could end up costing a great deal more! If you'd prefer to err on the side of caution, book well ahead of your departure date. In fact, Expedia has some of the biggest bargains up to a year in advance. If your preferred air carrier hasn't released tickets yet, check back frequently as deals are updated all the time on Expedia.

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Ontario nearby Airports

Los Angeles

St. Louis to Los Angeles Intl.
CA $445.84
*Available to Expedia members.