Latest deals
Insights
When to book
FAQs
Reviews
Price Alerts

Cheap flights from St. Louis to Los Angeles from $59

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from St. Louis to Los Angeles departing on 2/28. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.
1 adult
0 bags

Discover deals from 900+ travel sites with momondo.

Save money when you book flights with momondo

Big names and deals

Big names and deals

Search 100s of travel sites to compare prices.

Filter for what you want

Filter for what you want

Free Wi-Fi? Stopover? Instantly customize your results.

Trusted and free

Trusted and free

We’re completely free to use - no hidden charges or fees.

Price Alerts

Price Alerts

Not ready to book? to track prices.
Search flight deals

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
10:11 pm - 1:11 pm
STL
-
ONT
17h 00m
1 stop
Frontier Logo
6:15 am - 9:49 am
ONT
-
STL
25h 34m
1 stop
$128Frontier
Mon, Mar 2 - Tue, Mar 10
Frontier Logo
4:51 pm - 9:34 pm
STL
-
ONT
6h 43m
1 stop
Frontier Logo
8:40 am - 3:53 pm
ONT
-
STL
5h 13m
1 stop
$148Frontier
Wed, Feb 25 - Wed, Mar 4
Frontier Logo
1:54 pm - 11:59 pm
STL
-
ONT
12h 05m
1 stop
Frontier Logo
8:40 am - 3:53 pm
ONT
-
STL
5h 13m
1 stop
$158Frontier
Mon, Feb 23 - Wed, Feb 25
Frontier Logo
10:11 pm - 1:11 pm
STL
-
ONT
17h 00m
1 stop
Frontier Logo
2:23 pm - 9:49 am
ONT
-
STL
17h 26m
2 stops
$161Frontier
Mon, Mar 2 - Tue, Mar 10
Frontier Logo
1:54 pm - 11:59 pm
STL
-
ONT
12h 05m
1 stop
Frontier Logo
8:40 am - 3:53 pm
ONT
-
STL
5h 13m
1 stop
$185Frontier
Mon, Feb 23 - Wed, Feb 25
Frontier Logo
8:12 pm - 11:55 pm
STL
-
ONT
5h 43m
1 stop
Frontier Logo
11:44 am - 9:00 pm
ONT
-
STL
7h 16m
1 stop
$190Frontier
Thu, Apr 16 - Mon, Apr 20
Frontier Logo
9:55 pm - 6:34 pm
STL
-
ONT
22h 39m
1 stop
Frontier Logo
8:59 pm - 9:00 pm
ONT
-
STL
22h 01m
1 stop
$191Frontier
Mon, May 4 - Thu, May 7
Frontier Logo
8:17 pm - 11:59 pm
STL
-
ONT
29h 42m
2 stops
Frontier Logo
8:35 am - 3:53 pm
ONT
-
STL
29h 18m
1 stop
$195Frontier
Wed, Feb 18 - Tue, Feb 24
Frontier Logo
4:51 pm - 9:34 pm
STL
-
ONT
6h 43m
1 stop
Frontier Logo
8:35 am - 3:53 pm
ONT
-
STL
29h 18m
1 stop
$199Frontier
Wed, Feb 18 - Tue, Feb 24
Frontier Logo
8:12 pm - 11:55 pm
STL
-
ONT
5h 43m
1 stop
Frontier Logo
11:44 am - 9:00 pm
ONT
-
STL
7h 16m
1 stop
$201Frontier
Thu, Apr 23 - Mon, Apr 27

Frontier flights from St. Louis to Ontario

Our best Frontier deals on St. Louis to Ontario flight tickets
Frontier
Mar 2
STL10:11 pmLambert-St Louis
17h 00m
1 stop
ONT1:11 pmOntario
Mar 10
ONT6:15 amOntario
25h 34m
1 stop
STL9:49 amLambert-St Louis
$128
Frontier
Feb 25
STL4:51 pmLambert-St Louis
6h 43m
1 stop
ONT9:34 pmOntario
Mar 4
ONT8:40 amOntario
5h 13m
1 stop
STL3:53 pmLambert-St Louis
$148
Frontier
Feb 23
STL1:54 pmLambert-St Louis
12h 05m
1 stop
ONT11:59 pmOntario
Feb 25
ONT8:40 amOntario
5h 13m
1 stop
STL3:53 pmLambert-St Louis
$158

Delta flights from St. Louis to Ontario

Our best Delta deals on St. Louis to Ontario flight tickets
Delta
Feb 28
STL7:00 amLambert-St Louis
7h 07m
1 stop
ONT12:07 pmOntario
Mar 7
ONT1:10 pmOntario
6h 28m
1 stop
STL9:38 pmLambert-St Louis
$280
Delta
Feb 20
STL6:40 pmLambert-St Louis
7h 09m
1 stop
ONT11:49 pmOntario
Feb 23
ONT5:00 pmOntario
5h 25m
1 stop
STL12:25 amLambert-St Louis
$293

momondo Fare Finder

 
Customize your flight search to find flights from St. Louis to Ontario 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, momondo users made 832,500 searches. Data last updated January 27, 2026.
Use the filters below to find and compare flights from St. Louis to Ontario that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Mon 3/2

10:11 pm-1:11 pm

1 stop17h 00m

Ontario

Tue 3/10

6:15 am-9:49 am

1 stop25h 34m

$128

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Wed 2/25

4:51 pm-9:34 pm

1 stop6h 43m

Ontario

Wed 3/4

8:40 am-3:53 pm

1 stop5h 13m

$148

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Mon 2/23

1:54 pm-11:59 pm

1 stop12h 05m

Ontario

Wed 2/25

8:40 am-3:53 pm

1 stop5h 13m

$158

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Mon 3/2

10:11 pm-1:11 pm

1 stop17h 00m

Ontario

Tue 3/10

2:23 pm-9:49 am

2 stops17h 26m

$161

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Mon 2/23

1:54 pm-11:59 pm

1 stop12h 05m

Ontario

Wed 2/25

8:40 am-3:53 pm

1 stop5h 13m

$185

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Thu 4/16

8:12 pm-11:55 pm

1 stop5h 43m

Ontario

Mon 4/20

11:44 am-9:00 pm

1 stop7h 16m

$190

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Mon 5/4

9:55 pm-6:34 pm

1 stop22h 39m

Ontario

Thu 5/7

8:59 pm-9:00 pm

1 stop22h 01m

$191

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Wed 2/18

8:17 pm-11:59 pm

2 stops29h 42m

Ontario

Tue 2/24

8:35 am-3:53 pm

1 stop29h 18m

$195

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Wed 2/18

4:51 pm-9:34 pm

1 stop6h 43m

Ontario

Tue 2/24

8:35 am-3:53 pm

1 stop29h 18m

$199

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Thu 4/23

8:12 pm-11:55 pm

1 stop5h 43m

Ontario

Mon 4/27

11:44 am-9:00 pm

1 stop7h 16m

$201

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 20 resultsSorted by cheapest first
1
2

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 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 August instead. Flights to Ontario in August, while not as cheap as those in November, still average around $301.

How far in advance should I book a flight to Ontario?

You are more likely to see cheaper flights to Ontario from St. Louis when booking weeks ahead of your departure date. In general, you can expect to find flights to Ontario for around $346 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Ontario from St. Louis for as low as $130 on momondo.

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

As of January 2026, prices for St. Louis to Ontario flights are approximately 78% 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

Fastest flight time

5h 43m

Direct flights

None
The fastest flight from St. Louis to Ontario takes 5h 43m
There are no direct flights from St. Louis to Ontario. There are no popular flight routes from St. Louis to Ontario.
Search flight deals

  • 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 43m 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 $130Free CancellationRating
5.7
3,056 reviews
Search Frontier flights
DeltaPriceFrom $171Free CancellationRating
7.9
8,119 reviews
Search Delta flights
American AirlinesPriceFrom $264Free CancellationRating
7.2
11,197 reviews
Search American Airlines flights
SouthwestPriceFrom $292Free CancellationRating
8.0
4,268 reviews
Search Southwest flights
United AirlinesPriceFrom $292Free CancellationRating
7.4
9,205 reviews
Search United Airlines 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.
Start using Trips
Find my bookings

Get notified when prices go down

Daily price changes in your inbox - only with Price Alerts.
1 adult
Thu 2/26
Thu 3/5
By creating a price alert you accept our terms of use and privacy policy.

Find better results for your trip to the United States