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Cheap flights from St. Louis to Los Angeles from $89

1 adult
1 adult, Economy, 0 bags

Discover deals from 900+ travel sites with momondo.

Find the cheapest flights from St. Louis to Los Angeles

Cheap round-trip flights

Enter your travel dates to find the best prices.
Frontier Logo
8:10 pm - 10:30 amSTL  Lambert-St Louis-ONT Ontario
16h 20m1 stop Denver Intl
Frontier Logo
6:15 am - 7:17 pmONT  Ontario-STL Lambert-St Louis
11h 02m1 stop Denver Intl
$181Frontier
Fri, Oct 2 - Mon, Oct 5
Frontier Logo
12:17 pm - 10:30 amSTL  Lambert-St Louis-ONT Ontario
24h 13m2 stops Las Vegas Harry Reid Intl Denver Intl
Frontier Logo
6:15 am - 7:17 pmONT  Ontario-STL Lambert-St Louis
11h 02m1 stop Denver Intl
$193Frontier
Tue, Sep 29 - Sat, Oct 3
Multiple Airlines Logo
7:02 am - 1:16 pmSTL  Lambert-St Louis-ONT Ontario
8h 14m1 stop Seattle/Tacoma Intl
Multiple Airlines Logo
11:52 am - 3:24 pmONT  Ontario-STL Lambert-St Louis
25h 32m1 stop Denver Intl
$330Multiple Airlines
Tue, Oct 13 - Tue, Oct 20
Multiple Airlines Logo
7:02 am - 1:16 pmSTL  Lambert-St Louis-ONT Ontario
8h 14m1 stop Seattle/Tacoma Intl
Multiple Airlines Logo
11:52 am - 3:24 pmONT  Ontario-STL Lambert-St Louis
25h 32m1 stop Denver Intl
$337Multiple Airlines
Tue, Oct 13 - Tue, Oct 20
American Airlines Logo
11:31 am - 8:48 pmSTL  Lambert-St Louis-ONT Ontario
11h 17m1 stop Chicago O'Hare Intl
American Airlines Logo
6:00 am - 11:58 pmONT  Ontario-STL Lambert-St Louis
15h 58m1 stop Chicago O'Hare Intl
$345American Airlines
Sat, Feb 6 - Tue, Feb 9
American Airlines Logo
5:00 am - 12:03 pmSTL  Lambert-St Louis-ONT Ontario
9h 03m2 stops Dallas/Fort Worth Phoenix Sky Harbor Intl
American Airlines Logo
6:00 am - 9:08 pmONT  Ontario-STL Lambert-St Louis
13h 08m1 stop Chicago O'Hare Intl
$356American Airlines
Sat, Feb 6 - Tue, Feb 9
Southwest Logo
10:20 am - 4:15 pmSTL  Lambert-St Louis-ONT Ontario
7h 55m2 stops Denver Intl Las Vegas Harry Reid Intl
Southwest Logo
9:00 am - 6:30 pmONT  Ontario-STL Lambert-St Louis
7h 30m2 stops Las Vegas Harry Reid Intl Denver Intl
$386Southwest
Sat, Feb 6 - Tue, Feb 9
Southwest Logo
9:35 am - 3:40 pmSTL  Lambert-St Louis-ONT Ontario
8h 05m2 stops Phoenix Sky Harbor Intl Las Vegas Harry Reid Intl
Southwest Logo
8:40 am - 5:25 pmONT  Ontario-STL Lambert-St Louis
6h 45m2 stops Phoenix Sky Harbor Intl Omaha Eppley Airfield
$395Southwest
Fri, Oct 30 - Tue, Nov 3
United Airlines Logo
9:00 am - 6:16 pmSTL  Lambert-St Louis-ONT Ontario
11h 16m2 stops Denver Intl San Francisco
United Airlines Logo
6:00 am - 2:15 pmONT  Ontario-STL Lambert-St Louis
6h 15m1 stop Houston George Bush Intcntl
$418United Airlines
Wed, Sep 9 - Sun, Sep 13
United Airlines Logo
4:39 pm - 8:51 pmSTL  Lambert-St Louis-ONT Ontario
6h 12m1 stop Denver Intl
United Airlines Logo
5:00 am - 3:43 pmONT  Ontario-STL Lambert-St Louis
8h 43m2 stops Denver Intl Chicago O'Hare Intl
$462United Airlines
Mon, Oct 26 - Wed, Nov 4

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Frontier flights from St. Louis to Ontario

Our best Frontier deals on St. Louis to Ontario flight tickets
Frontier
Oct 2
STL8:10 pmLambert-St Louis
16h 20m
1 stop
ONT10:30 amOntario
Oct 5
ONT6:15 amOntario
11h 02m
1 stop
STL7:17 pmLambert-St Louis
$181
Frontier
Sep 29
STL12:17 pmLambert-St Louis
24h 13m
2 stops
ONT10:30 amOntario
Oct 3
ONT6:15 amOntario
11h 02m
1 stop
STL7:17 pmLambert-St Louis
$193
Frontier
Oct 1
STL10:20 amLambert-St Louis
15h 27m
2 stops
ONT11:47 pmOntario
Oct 5
ONT6:15 amOntario
11h 02m
1 stop
STL7:17 pmLambert-St Louis
$205

American Airlines flights from St. Louis to Ontario

Our best American Airlines deals on St. Louis to Ontario flight tickets
American Airlines
Sep 6
STL6:36 amLambert-St Louis
8h 55m
1 stop
ONT1:31 pmOntario
Sep 19
ONT6:15 amOntario
12h 29m
2 stops
STL8:44 pmLambert-St Louis
$414
American Airlines
Sep 6
STL6:36 amLambert-St Louis
8h 55m
1 stop
ONT1:31 pmOntario
Sep 19
ONT1:05 pmOntario
9h 22m
2 stops
STL12:27 amLambert-St Louis
$417
American Airlines
Sep 10
STL3:34 pmLambert-St Louis
9h 09m
2 stops
ONT10:43 pmOntario
Sep 14
ONT2:22 pmOntario
7h 21m
1 stop
STL11:43 pmLambert-St Louis
$418

momondo Fare Finder

 
Use the filters below to find and compare flights from St. Louis to Ontario that are best for you.

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Route

Depart

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Price

Cheapest round-trip

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Fri 10/2

8:10 pm-10:30 am

1 stop16h 20m

Ontario

Mon 10/5

6:15 am-7:17 pm

1 stop11h 02m

$181

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Tue 9/29

12:17 pm-10:30 am

2 stops24h 13m

Ontario

Sat 10/3

6:15 am-7:17 pm

1 stop11h 02m

$193

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Tue 10/13

7:02 am-1:16 pm

1 stop8h 14m

Ontario

Tue 10/20

11:52 am-3:24 pm

1 stop25h 32m

$330

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Tue 10/13

7:02 am-1:16 pm

1 stop8h 14m

Ontario

Tue 10/20

11:52 am-3:24 pm

1 stop25h 32m

$337

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Sat 2/6

11:31 am-8:48 pm

1 stop11h 17m

Ontario

Tue 2/9

6:00 am-11:58 pm

1 stop15h 58m

$345

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Sat 2/6

5:00 am-12:03 pm

2 stops9h 03m

Ontario

Tue 2/9

6:00 am-9:08 pm

1 stop13h 08m

$356

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Sat 2/6

10:20 am-4:15 pm

2 stops7h 55m

Ontario

Tue 2/9

9:00 am-6:30 pm

2 stops7h 30m

$386
Quickest round-trip

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Fri 10/30

9:35 am-3:40 pm

2 stops8h 05m

Ontario

Tue 11/3

8:40 am-5:25 pm

2 stops6h 45m

$395

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Wed 9/9

9:00 am-6:16 pm

2 stops11h 16m

Ontario

Sun 9/13

6:00 am-2:15 pm

1 stop6h 15m

$418

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Mon 10/26

4:39 pm-8:51 pm

1 stop6h 12m

Ontario

Wed 11/4

5:00 am-3:43 pm

2 stops8h 43m

$462

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 20 resultsSorted by cheapest first
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See travel insights to Los Angeles from

How to get the cheapest flight ticket from St. Louis to Ontario

Look no further. We've gone through all the searches for this route on momondo so you have the important information and insights to find the cheapest flight ticket for your trip

What is the typical price of a round-trip flight between St. Louis and Ontario?

Prices are currently low for flights on this route.

Typical prices usually range from $310 to $436.
The lowest price recently found on this route was $181.

What is the cheapest month to fly to Ontario?

In general, November is the cheapest month to fly from St. Louis to Ontario. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $292. If you aren’t able to travel during the month of November, then book flights to Ontario from St. Louis during October instead. Flights to Ontario in October, while not as cheap as those in November, still average around $314.

What is the cheapest Lambert-St Louis to Ontario flight route?

Fly from Lambert-St Louis to Ontario for the best Lambert-St Louis - Ontario flight prices

What cabin class options are available on St. Louis to Ontario flights?

There is only 1 cabin class available to choose from on St. Louis to Ontario flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

How have St. Louis to Ontario flight prices changed over time?

As of August 2026, prices for St. Louis to Ontario flights are approximately 86% more expensive when compared to flights at the same time last year.

When to book flights from St. Louis to Ontario

Are you open to changing your travel dates? Check out the ideal times to fly from St. Louis to Ontario according to our flight data. Find out which month and days have the cheapest flights.
Estimated round-trip price

Cheap St. Louis to Ontario (STL to ONT) flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from St. Louis to Ontario

Best Price Found

$89

Fastest flight time

5h 37m

Direct flights

None
The best one-way flight to Ontario from St. Louis in the past 72 hours is $89. The best round-trip flight deal from St. Louis to Ontario found on momondo in the last 72 hours is $181.
The fastest flight from St. Louis to Ontario takes 5h 37m
There are no direct flights from St. Louis to Ontario. There are no popular flight routes from St. Louis to Ontario.
Search flight deals

Frequently asked questions about flying from St. Louis to Ontario

  • How far is Lambert-St Louis to Ontario by plane?

    A flight from Lambert-St Louis to Ontario will travel around 1552.8 mi. 5h 37m is a normal flight duration for this route.

  • When did momondo last update prices for flights from Lambert-St Louis Airport to Ontario Airport?

    Prices for flights from Lambert-St Louis Airport to Ontario Airport are refreshed on a daily basis.

  • How many operators does momondo search for flights from Lambert-St Louis Airport to Ontario Airport?

  • How old do you have to be to fly from Lambert-St Louis Airport to Ontario Airport?

    The minimum age a child must be to fly alone is five but airlines that offer an unaccompanied minor (UNMR) service will have their own age restrictions, including rules around flight length, timings, and stopovers. We always recommend checking with the individual airline you are booking with to travel from Lambert-St Louis Airport to Ontario Airport.

  • What documentation or ID do you need to fly to Ontario Airport?

    The required travel and health documents for your Ontario Airport trip may vary depending on your itinerary and personal circumstances. As a general rule, you should carry multiple documents, including a national ID card or driver's license and a passport valid for six months after your intended arrival at Ontario Airport. We recommend that you seek guidance from your airline or a reliable third party such as IATA.

  • What is the most popular airline from St. Louis to Ontario?

Best airlines flying from St. Louis to Ontario

Compare and see reviews for airlines that fly from St. Louis to Ontario with momondo
Airline
Rating
Free Cancellation
Price
FrontierPriceFrom $143Free CancellationRating
5.6
2,640 reviews
Search Frontier flights
American AirlinesPriceFrom $292Free CancellationRating
7.1
12,026 reviews
Search American Airlines flights
SouthwestPriceFrom $292Free CancellationRating
8.0
4,201 reviews
Search Southwest flights
United AirlinesPriceFrom $292Free CancellationRating
7.4
10,135 reviews
Search United Airlines flights

  • Southwest Flights From St. Louis to Ontario

    Southwest operates around 3 flights from St. Louis to Ontario every week. The average price of these flights found in the last 72 hours has been $439, but momondo users have found Southwest deals from St. Louis to Ontario from as low as $292 round-trip. Southwest has been scored 8.0/10 in 4,201 reviews.

Why use momondo?

Why should I use momondo to find a flight deal from St. Louis to Ontario?

Finding the right flight to Ontario from St. Louis is quick and easy when you have a range of options in front of you, from reputable agents and recognisable airlines. Options that can then be filtered down to find the best fit. That is what momondo does. We make finding flights to Ontario quick and easy, saving you time and money.

Can I find flights from St. Louis to Ontario with flexible booking policies on momondo?

Yes. momondo enables you to select and highlight flights to Ontario from St. Louis with this policy.

How can momondo help me find flights from St. Louis to Ontario?

momondo helps you find the best flight between St. Louis and Ontario by providing filters to narrow your choice of flights to those matching your criteria. You can select flights based on numerous factors such as price, departure and landing times, airport and airline.

I’m not ready to book a flight from St. Louis to Ontario right now. Can momondo alert me if prices change?

If you are simply researching potential flights to Ontario, momondo offers a useful price alert feature which will track prices for flights to Ontario from St. Louis and alert you when they change.

An easier way to manage your Ontario trip

We make it super easy to schedule, organize and travel with friends or family. Trips is free — and available to use no matter where you book.
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