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ONT - STL

$102 Find Cheap Flights from Ontario to St. Louis - Compare and Save

1 adult
1 adult, Economy, 0 bags

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Everything you should know

Cheapest round-trip
$206
Typical prices: $268-$471
Frontier
Sun 11/11Wed 11/14
ONT - STL • 1 stop
Cheapest one-way
$102
Typical prices: $135-$260
Frontier
Mon 11/26
ONT - STL • 1 stop
Nonstop flights
Not available
There are currently no direct flights between Ontario and St. Louis. You'll need to take a connecting flight to reach the destination.
Insights
Insights
When to travel
April
Cheapest • 32% price drop
May
Most popular
Good to know
+1
Good to know
+1
Top layover airports
Las Vegas Harry Reid Intl (LAS)
Cheapest • Avg $292 (round-trip)
Phoenix Sky Harbor Intl (PHX)
Shortest trip • 5h 33m (one-way)
Insights
Insights
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Booking Insights
Flight Deals

Cheap Flights from Ontario to St. Louis (ONT-STL)

 
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from Ontario to St. Louis

Wed, Nov 11 - Sat, Nov 14
Frontier Logo
10:35 am - 12:33 pmONT  Ontario-STL Lambert-St Louis
23h 58m1 stop Las Vegas Harry Reid Intl
Frontier Logo
7:59 pm - 10:35 amSTL  Lambert-St Louis-ONT Ontario
16h 36m1 stop Denver Intl
$206Frontier
Wed, Nov 4 - Sat, Nov 7
Frontier Logo
6:30 am - 3:23 pmONT  Ontario-STL Lambert-St Louis
6h 53m1 stop Denver Intl
Frontier Logo
7:59 pm - 10:35 amSTL  Lambert-St Louis-ONT Ontario
16h 36m1 stop Denver Intl
$206Frontier
Tue, Nov 10 - Sat, Nov 14
Multiple Airlines Logo
11:52 am - 3:23 pmONT  Ontario-STL Lambert-St Louis
25h 31m1 stop Denver Intl
Multiple Airlines Logo
6:00 am - 3:13 pmSTL  Lambert-St Louis-ONT Ontario
11h 13m1 stop Seattle/Tacoma Intl
$243Multiple Airlines
Tue, Oct 27 - Tue, Nov 3
American Airlines Logo
2:22 pm - 10:00 pmONT  Ontario-STL Lambert-St Louis
5h 38m1 stop Dallas/Fort Worth
American Airlines Logo
5:00 am - 9:40 amSTL  Lambert-St Louis-ONT Ontario
6h 40m1 stop Dallas/Fort Worth
$267American Airlines
Tue, Nov 10 - Sat, Nov 14
Southwest Logo
8:40 am - 5:25 pmONT  Ontario-STL Lambert-St Louis
6h 45m2 stops Phoenix Sky Harbor Intl Omaha Eppley Airfield
Southwest Logo
6:20 am - 9:50 amSTL  Lambert-St Louis-ONT Ontario
5h 30m1 stop Phoenix Sky Harbor Intl
$268Southwest
Wed, Nov 11 - Sat, Nov 14
Southwest Logo
8:40 am - 5:25 pmONT  Ontario-STL Lambert-St Louis
6h 45m2 stops Phoenix Sky Harbor Intl Omaha Eppley Airfield
Southwest Logo
6:20 am - 9:50 amSTL  Lambert-St Louis-ONT Ontario
5h 30m1 stop Phoenix Sky Harbor Intl
$268Southwest
Tue, Oct 27 - Tue, Nov 3
American Airlines Logo
6:00 am - 5:02 pmONT  Ontario-STL Lambert-St Louis
9h 02m1 stop Dallas/Fort Worth
American Airlines Logo
8:29 am - 4:19 pmSTL  Lambert-St Louis-ONT Ontario
9h 50m2 stops Dallas/Fort Worth Phoenix Sky Harbor Intl
$272American Airlines
Thu, Nov 5 - Tue, Nov 10
Multiple Airlines Logo
8:03 pm - 8:54 amONT  Ontario-STL Lambert-St Louis
10h 51m1 stop Dallas/Fort Worth
Multiple Airlines Logo
6:00 am - 3:13 pmSTL  Lambert-St Louis-ONT Ontario
11h 13m1 stop Seattle/Tacoma Intl
$309Multiple Airlines
Sat, Dec 12 - Tue, Dec 22
Delta Logo
1:11 pm - 9:28 pmONT  Ontario-STL Lambert-St Louis
6h 17m1 stop Salt Lake City
Delta Logo
7:38 pm - 11:59 pmSTL  Lambert-St Louis-ONT Ontario
6h 21m1 stop Salt Lake City
$345Delta
Sat, Dec 12 - Sun, Dec 20
Delta Logo
1:11 pm - 9:28 pmONT  Ontario-STL Lambert-St Louis
6h 17m1 stop Salt Lake City
Delta Logo
7:38 pm - 11:59 pmSTL  Lambert-St Louis-ONT Ontario
6h 21m1 stop Salt Lake City
$354Delta
Booking Insights

Price, demand and travel trends for Ontario to St. Louis flights

Use KAYAK data on prices, travel dates, airlines and seasonal trends to compare options and book flights with more confidence.

How much is a round-trip flight from Ontario to St. Louis?

Round-trip flights from Ontario to St. Louis typically range from $268 to $471. The lowest price found in the past 5 days was $206, on Frontier.

What's the cheapest day of the week to fly from Ontario to St. Louis?

Based on deals KAYAK users found in the last 12 months, Thursday is the cheapest day of the week to fly from Ontario to St. Louis. It’s 19% cheaper than the average day, while Tuesday is the most expensive, with prices 25% higher.

What’s the cheapest month to fly from Ontario to St. Louis?

•April is the cheapest month to fly from Ontario to St. Louis at $250 round-trip.
•December ($451) and June ($439) are the most expensive months.
•The price difference between flying in the cheapest and most expensive months is 80% on average.
This is based on KAYAK aggregated and averaged internal data over the past 12 months.

Find deals

Key details for Ontario to St. Louis flights

Low season

January

Cheapest flight

$102
Beat the crowds with an average 45% drop in travelers.
The most popular month to fly with an average 82% increase in travelers.
One-way flight from Ontario to St. Louis

When to book flights from Ontario to St. Louis

Are your dates flexible? Find out the best times to travel from Ontario to St. Louis based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price

Your Ontario to St. Louis flight questions, answered

Find helpful answers about this route, including flight times, airports, airlines and booking tips.

  • What cabin classes can I book on flights from Ontario to St. Louis?

    Two cabin classes are available on flights from Ontario to St. Louis:

    • Economy Class
    • First Class

  • How long is a flight from Ontario to St. Louis?

    A nonstop flight from Ontario to St. Louis takes 00m, covering 1,541 miles.

  • Do I need a passport to fly from Ontario to St. Louis?

    No, a passport is not required for this domestic route, but you will need a real ID-compliant driver's license, a state ID or another TSA-accepted form of identification.

  • How much should I expect to pay for a Ontario to St. Louis flight?

    Round-trip flights from Ontario to St. Louis range from $268 to $471, with an average of $366 over the past 12 months. Anything below $268 counts as a good deal.

  • How are flight prices from Ontario to St. Louis looking right now?

    One-way fares from Ontario to St. Louis are currently lower than usual. Average one-way flight prices are about $160, which is 10% below the typical average for this route.

  • What car rental options are available at Lambert-St Louis Airport (STL)?

    Lambert-St Louis Airport (STL) hosts 5 major car rental companies, with daily rates starting from around $31 for economy cars. Top options include:

    • Hertz
    • Budget
    • Alamo
    • Enterprise Rent-A-Car
    • Payless

  • Which airports can I use when flying from Ontario to St. Louis?

    Flights from Ontario to St. Louis usually depart from Ontario (ONT) and arrive at Lambert-St Louis (STL).

  • Which airports do connecting flights from Ontario to St. Louis pass through?

    One-stop flights from Ontario to St. Louis most commonly connect through:

    • Denver Intl (DEN) - 41% of one-stop connections
    • Las Vegas Harry Reid Intl (LAS) - 21% of one-stop connections
    • Phoenix Sky Harbor Intl (PHX) - 20% of one-stop connections
    • Dallas/Fort Worth (DFW) - 12% of one-stop connections

  • Can I save money by using flexible dates for flights from Ontario to St. Louis?

    Yes. Flexible dates can save you up to 35% on flights from Ontario to St. Louis. Thursday is the cheapest departure day at $300 round-trip on average, while Tuesday is the most expensive at $459, a difference of $159.

    KAYAK's flexible dates feature shows options up to 3 days before and after your selected dates, making it easier to compare nearby fares.

  • How much time can I save by choosing a different layover airport from Ontario to St. Louis?

    Flying via Phoenix Sky Harbor Intl (PHX) gives the shortest average 1-stop total travel time at 5h 33m, compared with 6h via Salt Lake City (SLC) and 6h 45m via Dallas/Fort Worth (DFW).

  • What is the time difference between Ontario and St. Louis?

    St. Louis is 2 hours ahead of Ontario (Central Time vs Pacific Time). Plan for the time shift when scheduling connections or first-day activities.

  • What popular places can I visit in St. Louis?

    Some of the most popular sights in St. Louis are Busch Stadium, Enterprise Center and America's Center Convention Complex. These are among the most viewed places in St. Louis on KAYAK.

Your guide to booking Ontario to St. Louis flights

Get tips on when to book, when to fly and what to know before your trip.
  • If your dates are flexible, aim for a Thursday departure and avoid flying on Tuesday. On this route, Thursday flights average $300, about $159 less than Tuesday fares (35% savings) based on the last 12 months.
  • If you can choose when to travel, plan your Ontario to St. Louis trip for April. Fares historically average $250 round-trip in that month - typically $201 less than the most expensive month, which is December (based on the last 12 months).
  • If you're arriving late at night and need somewhere to stay, check out these hotels close to Lambert-St Louis Airport.

    • Renaissance St. Louis Airport Hotel
    • Drury Inn & Suites St. Louis Airport
    • DoubleTree by Hilton St. Louis Airport

More options for your flight from Ontario to St. Louis

Complete your trip to St. Louis with a hotel stay or car rental

Car rentals in St. Louis
Hotels in St. Louis
Vacations in St. Louis