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Cheap flights from St. Louis to Los Angeles from $101

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
7:02 pm - 12:05 amSTL  Lambert-St Louis-ONT Ontario
7h 03m1 stop Denver Intl
Frontier Logo
6:30 am - 10:20 amONT  Ontario-STL Lambert-St Louis
25h 50m1 stop Denver Intl
$194Frontier
Sat, Feb 27 - Tue, Mar 2
Frontier Logo
7:54 pm - 10:45 amSTL  Lambert-St Louis-ONT Ontario
16h 51m1 stop Denver Intl
Frontier Logo
3:33 pm - 9:37 pmONT  Ontario-STL Lambert-St Louis
28h 04m1 stop Las Vegas Harry Reid Intl
$214Frontier
Sat, Dec 12 - Sat, Jan 9
Multiple Airlines Logo
7:54 pm - 12:20 amSTL  Lambert-St Louis-ONT Ontario
6h 26m1 stop Denver Intl
Multiple Airlines Logo
4:16 pm - 2:56 pmONT  Ontario-STL Lambert-St Louis
20h 40m1 stop Seattle/Tacoma Intl
$261Multiple Airlines
Fri, Dec 11 - Mon, Jan 11
Southwest Logo
6:20 am - 9:50 amSTL  Lambert-St Louis-ONT Ontario
5h 30m1 stop Phoenix Sky Harbor Intl
Southwest Logo
5:35 am - 1:50 pmONT  Ontario-STL Lambert-St Louis
6h 15m1 stop Las Vegas Harry Reid Intl
$274Southwest
Sat, Dec 12 - Sat, Jan 9
Southwest Logo
8:25 am - 2:50 pmSTL  Lambert-St Louis-ONT Ontario
8h 25m1 stop Sacramento Intl
Southwest Logo
8:00 am - 4:05 pmONT  Ontario-STL Lambert-St Louis
6h 05m1 stop Las Vegas Harry Reid Intl
$279Southwest
Thu, Dec 10 - Sat, Jan 9
Alaska Airlines Logo
3:54 pm - 10:41 pmSTL  Lambert-St Louis-ONT Ontario
8h 47m1 stop Seattle/Tacoma Intl
Alaska Airlines Logo
7:00 am - 2:56 pmONT  Ontario-STL Lambert-St Louis
29h 56m1 stop Seattle/Tacoma Intl
$279Alaska Airlines
Wed, Jan 20 - Mon, Jan 25
American Airlines Logo
9:41 am - 3:29 pmSTL  Lambert-St Louis-ONT Ontario
7h 48m2 stops Dallas/Fort Worth Phoenix Sky Harbor Intl
American Airlines Logo
4:19 pm - 11:55 pmONT  Ontario-STL Lambert-St Louis
5h 36m1 stop Phoenix Sky Harbor Intl
$284American Airlines
Wed, Jan 20 - Mon, Jan 25
American Airlines Logo
10:25 am - 6:27 pmSTL  Lambert-St Louis-ONT Ontario
10h 02m2 stops Dallas/Fort Worth Phoenix Sky Harbor Intl
American Airlines Logo
6:20 am - 1:38 pmONT  Ontario-STL Lambert-St Louis
5h 18m1 stop Phoenix Sky Harbor Intl
$284American Airlines
Sat, Dec 12 - Sat, Jan 9
United Airlines Logo
8:40 am - 5:36 pmSTL  Lambert-St Louis-ONT Ontario
10h 56m2 stops Denver Intl San Francisco
United Airlines Logo
5:00 am - 2:03 pmONT  Ontario-STL Lambert-St Louis
7h 03m1 stop Denver Intl
$284United Airlines
Thu, Dec 10 - Sat, Jan 9
United Airlines Logo
8:40 am - 5:36 pmSTL  Lambert-St Louis-ONT Ontario
10h 56m2 stops Denver Intl San Francisco
United Airlines Logo
5:00 am - 2:03 pmONT  Ontario-STL Lambert-St Louis
7h 03m1 stop Denver Intl
$284United Airlines
Wed, Dec 9 - Sat, Jan 9

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Frontier flights from St. Louis to Ontario

Our best Frontier deals on St. Louis to Ontario flight tickets
Frontier
Feb 27
STL7:02 pmLambert-St Louis
7h 03m
1 stop
ONT12:05 amOntario
Mar 2
ONT6:30 amOntario
25h 50m
1 stop
STL10:20 amLambert-St Louis
$194
Frontier
Dec 12
STL7:54 pmLambert-St Louis
16h 51m
1 stop
ONT10:45 amOntario
Jan 9
ONT3:33 pmOntario
28h 04m
1 stop
STL9:37 pmLambert-St Louis
$214
Frontier
Nov 12
STL12:14 pmLambert-St Louis
8h 54m
1 stop
ONT7:08 pmOntario
Nov 14
ONT11:52 amOntario
5h 22m
1 stop
STL7:14 pmLambert-St Louis
$216

American Airlines flights from St. Louis to Ontario

Our best American Airlines deals on St. Louis to Ontario flight tickets
American Airlines
Dec 12
STL10:25 amLambert-St Louis
10h 02m
2 stops
ONT6:27 pmOntario
Jan 9
ONT9:28 amOntario
8h 33m
2 stops
STL8:01 pmLambert-St Louis
$289
American Airlines
Jan 10
STL5:05 amLambert-St Louis
9h 34m
2 stops
ONT12:39 pmOntario
Jan 14
ONT7:00 amOntario
5h 55m
1 stop
STL2:55 pmLambert-St Louis
$307

momondo Fare Finder

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

Fly from

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Route

Depart

Return

Price

Cheapest round-trip

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Sat 2/27

7:02 pm-12:05 am

1 stop7h 03m

Ontario

Tue 3/2

6:30 am-10:20 am

1 stop25h 50m

$194

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Sat 12/12

7:54 pm-10:45 am

1 stop16h 51m

Ontario

Sat 1/9

3:33 pm-9:37 pm

1 stop28h 04m

$214

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Fri 12/11

7:54 pm-12:20 am

1 stop6h 26m

Ontario

Mon 1/11

4:16 pm-2:56 pm

1 stop20h 40m

$261
Quickest round-trip

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Sat 12/12

6:20 am-9:50 am

1 stop5h 30m

Ontario

Sat 1/9

5:35 am-1:50 pm

1 stop6h 15m

$274

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Thu 12/10

8:25 am-2:50 pm

1 stop8h 25m

Ontario

Sat 1/9

8:00 am-4:05 pm

1 stop6h 05m

$279

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Wed 1/20

3:54 pm-10:41 pm

1 stop8h 47m

Ontario

Mon 1/25

7:00 am-2:56 pm

1 stop29h 56m

$279

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Wed 1/20

9:41 am-3:29 pm

2 stops7h 48m

Ontario

Mon 1/25

4:19 pm-11:55 pm

1 stop5h 36m

$284

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Sat 12/12

10:25 am-6:27 pm

2 stops10h 02m

Ontario

Sat 1/9

6:20 am-1:38 pm

1 stop5h 18m

$284

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Thu 12/10

8:40 am-5:36 pm

2 stops10h 56m

Ontario

Sat 1/9

5:00 am-2:03 pm

1 stop7h 03m

$284

St. LouisOntario

STL Lambert-St Louis - ONT Ontario

STLONT

Lambert-St Louis

Wed 12/9

8:40 am-5:36 pm

2 stops10h 56m

Ontario

Sat 1/9

5:00 am-2:03 pm

1 stop7h 03m

$284

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 20 resultsSorted by cheapest first
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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 $284 to $565.
The lowest price recently found on this route was $194.

What is the cheapest month to fly to Ontario?

In general, December 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 $308. If you aren’t able to travel during the month of December, then book flights to Ontario from St. Louis during April instead. Flights to Ontario in April, while not as cheap as those in December, still average around $343.

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 October 2026, prices for St. Louis to Ontario flights are approximately 233% 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

$101

Fastest flight time

5h 58m

Direct flights

None
The best one-way flight to Ontario from St. Louis in the past 72 hours is $101. The best round-trip flight deal from St. Louis to Ontario found on momondo in the last 72 hours is $194.
The fastest flight from St. Louis to Ontario takes 5h 58m
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 58m 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 $144Free CancellationRating
5.5
2,519 reviews
Search Frontier flights
American AirlinesPriceFrom $292Free CancellationRating
7.0
12,191 reviews
Search American Airlines flights
United AirlinesPriceFrom $292Free CancellationRating
7.3
10,407 reviews
Search United Airlines flights
SouthwestPriceFrom $343Free CancellationRating
7.9
4,211 reviews
Search Southwest flights

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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