STL - ONT

$81 Find Cheap Flights from St. Louis to Ontario - Compare and Save

1 adult
1 adult, Economy, 0 bags

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Everything you should know

Cheapest round-trip
$165
Typical prices: $292-$475
Frontier
Fri 12/7Sat 12/15
STL - ONT • 1 stop
Cheapest one-way
$81
Typical prices: $132-$296
Frontier
Wed 10/17
STL - ONT • 1 stop
Nonstop flights
Not available
There are currently no direct flights between St. Louis and Ontario. You'll need to take a connecting flight to reach the destination.
Insights
Insights
When to travel
November
Cheapest • 22% price drop
July
Most popular
Good to know
+1
Good to know
+1
Top layover airports
Dallas/Fort Worth (DFW)
Cheapest • Avg $384 (round-trip)
Phoenix Sky Harbor Intl (PHX)
Shortest trip • 5h 27m (one-way)
Insights
Insights
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Booking Insights
Flight Deals

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

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

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

Mon, Dec 7 - Tue, Dec 15
Frontier Logo
7:54 pm - 10:45 amSTL  Lambert-St Louis-ONT Ontario
16h 51m1 stop Denver Intl
Frontier Logo
6:00 am - 11:04 amONT  Ontario-STL Lambert-St Louis
27h 04m1 stop Denver Intl
$165Frontier
Sat, Nov 7 - Sat, Nov 14
Frontier Logo
7:59 pm - 11:51 pmSTL  Lambert-St Louis-ONT Ontario
5h 52m1 stop Denver Intl
Frontier Logo
6:25 am - 7:14 pmONT  Ontario-STL Lambert-St Louis
10h 49m1 stop Denver Intl
$171Frontier
Tue, Oct 20 - Tue, Oct 27
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 - 3:23 pmONT  Ontario-STL Lambert-St Louis
25h 31m1 stop Denver Intl
$302Multiple Airlines
Tue, Nov 3 - Sat, Nov 7
Multiple Airlines Logo
6:00 am - 3:13 pmSTL  Lambert-St Louis-ONT Ontario
11h 13m1 stop Seattle/Tacoma Intl
Multiple Airlines Logo
11:52 am - 7:14 pmONT  Ontario-STL Lambert-St Louis
5h 22m1 stop Denver Intl
$308Multiple Airlines
Fri, Oct 9 - Mon, Oct 12
American Airlines Logo
5:40 am - 9:35 amSTL  Lambert-St Louis-ONT Ontario
5h 55m1 stop Dallas/Fort Worth
American Airlines Logo
11:59 pm - 9:20 amONT  Ontario-STL Lambert-St Louis
7h 21m1 stop Dallas/Fort Worth
$365American Airlines
Thu, Oct 8 - Mon, Oct 12
American Airlines Logo
5:40 am - 9:35 amSTL  Lambert-St Louis-ONT Ontario
5h 55m1 stop Dallas/Fort Worth
American Airlines Logo
11:59 pm - 9:20 amONT  Ontario-STL Lambert-St Louis
7h 21m1 stop Dallas/Fort Worth
$365American Airlines
Thu, Jan 21 - Sun, Jan 24
Southwest Logo
5:45 am - 9:25 amSTL  Lambert-St Louis-ONT Ontario
5h 40m1 stop Phoenix Sky Harbor Intl
Southwest Logo
6:45 am - 4:35 pmONT  Ontario-STL Lambert-St Louis
7h 50m1 stop Chicago Midway
$395Southwest
Thu, Jan 21 - Sun, Jan 24
Southwest Logo
8:30 am - 2:30 pmSTL  Lambert-St Louis-ONT Ontario
8h 00m1 stop Austin Bergstrom
Southwest Logo
7:40 am - 4:35 pmONT  Ontario-STL Lambert-St Louis
6h 55m2 stops Phoenix Sky Harbor Intl Dallas Love Field
$400Southwest
Sun, Nov 22 - Fri, Nov 27
United Airlines Logo
9:40 am - 5:56 pmSTL  Lambert-St Louis-ONT Ontario
10h 16m2 stops Chicago O'Hare Intl San Francisco
United Airlines Logo
5:00 am - 12:38 pmONT  Ontario-STL Lambert-St Louis
5h 38m1 stop Denver Intl
$464United Airlines
Fri, Nov 6 - Mon, Nov 9
United Airlines Logo
1:40 pm - 10:48 pmSTL  Lambert-St Louis-ONT Ontario
11h 08m2 stops Denver Intl San Francisco
United Airlines Logo
1:35 pm - 10:15 pmONT  Ontario-STL Lambert-St Louis
6h 40m1 stop San Francisco
$512United Airlines
Booking Insights

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

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

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

Round-trip flights from St. Louis to Ontario start at $165. Prices are below average for this route right now, with typical round-trip fares ranging from $292 to $475. The lowest price found in the past 5 days was $165 on Frontier.

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

Tuesday is the cheapest day of the week to fly from St. Louis to Ontario, it is 11% cheaper than the average day. Sunday is the most expensive day with flight prices 59% higher than average. Based on deals found by KAYAK users in the last 12 months.

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

•November is the cheapest month to fly from St. Louis to Ontario at $292 round-trip.
•June ($510) and March ($424) are the most expensive months.
•The price difference between flying in the cheapest and most expensive months is 74% on average.
This is based on KAYAK aggregated and averaged internal data over the past 12 months.

Find deals

Key details for St. Louis to Ontario flights

Low season

February

Cheapest flight

$81
Most popular time to fly with an average 11% increase in price.
Flight from St. Louis to Ontario

When to book flights from St. Louis to Ontario

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

Your St. Louis to Ontario flight questions, answered

Find helpful route details based on KAYAK data, including flight times, airports, airlines and booking questions.

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

    Only Economy Class is available on flights from St. Louis to Ontario.

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

    A nonstop flight from St. Louis to Ontario takes 0h 00m, covering 1,541 miles.

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

    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 St. Louis to Ontario flight?

    Round-trip flights from St. Louis to Ontario range from $292 to $475, with an average of $375 over the past 12 months. Anything below $292 counts as a good deal.

  • Have flight prices from St. Louis to Ontario changed much recently?

    Yes. Based on fares seen in the past 5 days, round-trip prices on this route showed a wide range, from about $165 to $1,626. That means the highest observed fare was about 10x higher than the lowest one.

  • Which airlines offer Wi-Fi on St. Louis to Ontario flights?

    JetBlue is the only airline on the St. Louis to Ontario route offering in-flight Wi-Fi. Pricing depends on fare class.

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

    One-way fares from St. Louis to Ontario are currently higher than usual. Average one-way flight prices are about $301, which is 65% above the typical average for this route.

  • What car rental options are available at Ontario Airport (ONT)?

    Ontario Airport (ONT) hosts 5 major car rental companies, with daily rates starting from around $18 for economy cars. Top options include:
    • Fox
    • Thrifty
    • Europcar
    • Dollar
    • Alamo

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

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

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

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

    • Denver Intl (DEN) - 53% of one-stop connections
    • Las Vegas Harry Reid Intl (LAS) - 15% of one-stop connections
    • Dallas/Fort Worth (DFW) - 13% of one-stop connections
    • Phoenix Sky Harbor Intl (PHX) - 12% of one-stop connections

    Denver Intl (DEN) handles the largest share of one-stop connections on this route.

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

    Yes. Being flexible with your travel dates can save you up to 44% on the St. Louis to Ontario route. Tuesday is the cheapest departure day at $336 round-trip on average, while Sunday is the most expensive at $598, a difference of $262. 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 St. Louis to Ontario?

    Flying via Phoenix Sky Harbor Intl (PHX) gives the shortest average 1-stop total travel time at 5h 27m, compared with 6h 01m via Salt Lake City (SLC) and 6h 09m via Sacramento Intl (SMF).

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

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

  • What popular places can I visit in Ontario?

    Some of the most popular sights in Ontario are Ontario Convention Center and Cucamonga-Guasti Regional Park. These are among the most viewed places in Ontario on KAYAK.

  • Which airlines include bags at no extra cost on St. Louis to Ontario flights?

    Here are some options for this route, based on selected ticket types and cabin classes:

    • JetBlue: a cabin bag in Economy Class class

    Bag allowance can vary by ticket type, cabin class, route and airline, so travelers should check the fare details before booking.

Your guide to booking St. Louis to Ontario flights

Get tips on when to book, when to fly and what to know before your trip.
  • If your dates can be flexible, aim for a Tuesday departure instead of Sunday. On this route, Tuesday flights average $336 - about $262 less than Sunday (44% savings) based on the last 12 months.
  • If you can choose when to travel, plan your St. Louis to Ontario trip for November. Fares historically average $292 round-trip in that month - typically $218 less than the most expensive month, which is June (based on the last 12 months).
  • If you're arriving late at night and need somewhere to stay, check out these hotels close to Ontario Airport.
    - Azure Hotel & Suites, Trademark Collection by Wyndham
    - La Quinta Inn & Suites by Wyndham Ontario Airport
    - Ontario Airport Inn

More options for your flight from St. Louis to Ontario

Complete your trip to Ontario with a hotel stay or car rental

Car rentals in Ontario
Hotels in Ontario
Vacations in Ontario