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Cheap flights from St. Louis to Los Angeles from $63

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 2/21. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.
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0 bags

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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
2:51 pm - 11:59 pm
STL
-
ONT
11h 08m
1 stop
Frontier Logo
2:08 pm - 1:09 pm
ONT
-
STL
21h 01m
1 stop
$141Frontier
sáb., feb. 21 - jue., feb. 26
Frontier Logo
2:51 pm - 11:59 pm
STL
-
ONT
11h 08m
1 stop
Frontier Logo
6:00 am - 1:56 pm
ONT
-
STL
5h 56m
1 stop
$148Frontier
sáb., feb. 21 - sáb., feb. 28
Frontier Logo
8:12 pm - 11:59 pm
STL
-
ONT
5h 47m
1 stop
Frontier Logo
4:49 pm - 11:19 am
ONT
-
STL
16h 30m
1 stop
$151Frontier
sáb., mar. 7 - mar., mar. 24
Frontier Logo
2:51 pm - 11:59 pm
STL
-
ONT
11h 08m
1 stop
Frontier Logo
6:00 am - 1:56 pm
ONT
-
STL
5h 56m
1 stop
$156Frontier
sáb., feb. 14 - sáb., feb. 21
Frontier Logo
2:51 pm - 11:59 pm
STL
-
ONT
11h 08m
1 stop
Frontier Logo
7:17 pm - 9:26 pm
ONT
-
STL
24h 09m
1 stop
$161Frontier
sáb., feb. 14 - mié., feb. 18
Frontier Logo
2:51 pm - 11:59 pm
STL
-
ONT
11h 08m
1 stop
Frontier Logo
6:00 am - 1:56 pm
ONT
-
STL
5h 56m
1 stop
$164Frontier
sáb., feb. 21 - sáb., feb. 28
Frontier Logo
10:11 pm - 1:11 pm
STL
-
ONT
17h 00m
1 stop
Frontier Logo
8:40 am - 6:51 am
ONT
-
STL
20h 11m
2 stops
$166Frontier
dom., mar. 1 - mar., mar. 3
Frontier Logo
10:01 pm - 7:53 pm
STL
-
ONT
23h 52m
1 stop
Frontier Logo
1:05 pm - 8:50 pm
ONT
-
STL
5h 45m
1 stop
$171Frontier
jue., ene. 29 - lun., feb. 2
Frontier Logo
2:51 pm - 11:59 pm
STL
-
ONT
11h 08m
1 stop
Frontier Logo
7:30 am - 11:59 pm
ONT
-
STL
38h 29m
2 stops
$179Frontier
sáb., feb. 14 - mié., feb. 18
Frontier Logo
3:46 pm - 11:24 pm
STL
-
ONT
9h 38m
1 stop
Frontier Logo
6:00 am - 1:56 pm
ONT
-
STL
5h 56m
1 stop
$180Frontier
sáb., feb. 7 - sáb., feb. 14

Frontier flights from St. Louis to Ontario

Our best Frontier deals on St. Louis to Ontario flight tickets
Frontier
Feb 21
STL2:51 pmLambert-St Louis
11h 08m
1 stop
ONT11:59 pmOntario
Feb 26
ONT2:08 pmOntario
21h 01m
1 stop
STL1:09 pmLambert-St Louis
$141
Frontier
Feb 21
STL2:51 pmLambert-St Louis
11h 08m
1 stop
ONT11:59 pmOntario
Feb 28
ONT6:00 amOntario
5h 56m
1 stop
STL1:56 pmLambert-St Louis
$148
Frontier
Mar 7
STL8:12 pmLambert-St Louis
5h 47m
1 stop
ONT11:59 pmOntario
Mar 24
ONT4:49 pmOntario
16h 30m
1 stop
STL11:19 amLambert-St Louis
$151

Delta flights from St. Louis to Ontario

Our best Delta deals on St. Louis to Ontario flight tickets
Delta
Jan 29
STL6:40 amLambert-St Louis
7h 36m
1 stop
ONT12:16 pmOntario
Feb 3
ONT3:30 pmOntario
21h 08m
2 stops
STL2:38 pmLambert-St Louis
$545
Delta
Jan 29
STL6:40 amLambert-St Louis
7h 36m
1 stop
ONT12:16 pmOntario
Feb 3
ONT1:11 pmOntario
6h 27m
1 stop
STL9:38 pmLambert-St Louis
$557
Delta
Jan 29
STL6:40 amLambert-St Louis
7h 36m
1 stop
ONT12:16 pmOntario
Feb 2
ONT10:30 pmOntario
19h 36m
2 stops
STL8:06 pmLambert-St Louis
$582

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 enero 15, 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

sáb. 2/21

2:51 pm-11:59 pm

1 stop11h 08m

Ontario

jue. 2/26

2:08 pm-1:09 pm

1 stop21h 01m

$141

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

sáb. 2/21

2:51 pm-11:59 pm

1 stop11h 08m

Ontario

sáb. 2/28

6:00 am-1:56 pm

1 stop5h 56m

$148

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

sáb. 3/7

8:12 pm-11:59 pm

1 stop5h 47m

Ontario

mar. 3/24

4:49 pm-11:19 am

1 stop16h 30m

$151

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

sáb. 2/14

2:51 pm-11:59 pm

1 stop11h 08m

Ontario

sáb. 2/21

6:00 am-1:56 pm

1 stop5h 56m

$156

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

sáb. 2/14

2:51 pm-11:59 pm

1 stop11h 08m

Ontario

mié. 2/18

7:17 pm-9:26 pm

1 stop24h 09m

$161

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

sáb. 2/21

2:51 pm-11:59 pm

1 stop11h 08m

Ontario

sáb. 2/28

6:00 am-1:56 pm

1 stop5h 56m

$164

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

dom. 3/1

10:11 pm-1:11 pm

1 stop17h 00m

Ontario

mar. 3/3

8:40 am-6:51 am

2 stops20h 11m

$166

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

jue. 1/29

10:01 pm-7:53 pm

1 stop23h 52m

Ontario

lun. 2/2

1:05 pm-8:50 pm

1 stop5h 45m

$171

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

sáb. 2/14

2:51 pm-11:59 pm

1 stop11h 08m

Ontario

mié. 2/18

7:30 am-11:59 pm

2 stops38h 29m

$179

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

sáb. 2/7

3:46 pm-11:24 pm

1 stop9h 38m

Ontario

sáb. 2/14

6:00 am-1:56 pm

1 stop5h 56m

$180

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?

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 $348 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 141% 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 47m

Direct flights

None
The fastest flight from St. Louis to Ontario takes 5h 47m
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 47m 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
3,057 reviews
Search Frontier flights
DeltaPriceFrom $171Free CancellationRating
7.9
8,051 reviews
Search Delta flights
United AirlinesPriceFrom $201Free CancellationRating
7.4
9,164 reviews
Search United Airlines flights
American AirlinesPriceFrom $264Free CancellationRating
7.2
11,136 reviews
Search American Airlines flights
SouthwestPriceFrom $292Free CancellationRating
8.0
4,258 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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