STL - ONT

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

1 adult
1 adult, Economy, 0 bags

Save 21% or more on flights. Compare deals from all over the web.

Never overpay with our price tracking tools.

Filter searches by price, airline and more to find your best flights.

Everything you should know

Cheapest round-trip
$146
Typical prices: $292-$475
Frontier
Tue 11/13Sun 11/18
STL - ONT • 1 stop
Cheapest one-way
$81
Typical prices: $132-$296
Frontier
Wed 10/10
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
Start a new search
KAYAK searches 100s of sites at once to find you the best travel deals.
We hope you love your trip to Ontario!
Flight Deals
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, Oct 5 - Wed, Oct 7
Frontier Logo
8:10 pm - 10:30 amSTL  Lambert-St Louis-ONT Ontario
16h 20m1 stop Denver Intl
Frontier Logo
11:45 am - 11:59 pmONT  Ontario-STL Lambert-St Louis
10h 14m1 stop Denver Intl
$165Frontier
Wed, Nov 4 - Sat, Nov 7
Frontier Logo
4:18 pm - 11:51 pmSTL  Lambert-St Louis-ONT Ontario
9h 33m1 stop Denver Intl
Frontier Logo
11:52 am - 7:14 pmONT  Ontario-STL Lambert-St Louis
5h 22m1 stop Denver Intl
$169Frontier
Tue, Oct 20 - Sat, Oct 24
Multiple Airlines Logo
7:02 am - 1:16 pmSTL  Lambert-St Louis-ONT Ontario
8h 14m1 stop Seattle/Tacoma Intl
Multiple Airlines Logo
6:15 am - 6:57 pmONT  Ontario-STL Lambert-St Louis
10h 42m1 stop Denver Intl
$267Multiple Airlines
Tue, Oct 20 - Sat, Oct 24
Multiple Airlines Logo
7:02 am - 1:16 pmSTL  Lambert-St Louis-ONT Ontario
8h 14m1 stop Seattle/Tacoma Intl
Multiple Airlines Logo
6:15 am - 6:57 pmONT  Ontario-STL Lambert-St Louis
10h 42m1 stop Denver Intl
$270Multiple Airlines
Tue, Oct 13 - Tue, Oct 20
Southwest Logo
5:20 am - 10:45 amSTL  Lambert-St Louis-ONT Ontario
7h 25m1 stop Las Vegas Harry Reid Intl
Southwest Logo
11:55 pm - 10:50 amONT  Ontario-STL Lambert-St Louis
8h 55m1 stop Chicago Midway
$357Southwest
Thu, Dec 3 - Tue, Dec 8
Southwest Logo
5:00 pm - 10:00 pmSTL  Lambert-St Louis-ONT Ontario
7h 00m1 stop Houston Hobby
Southwest Logo
6:25 am - 5:25 pmONT  Ontario-STL Lambert-St Louis
9h 00m1 stop Sacramento Intl
$357Southwest
Thu, Oct 15 - Mon, Oct 19
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
$357American Airlines
Tue, Oct 20 - Mon, Oct 26
American Airlines Logo
5:40 am - 12:14 pmSTL  Lambert-St Louis-ONT Ontario
8h 34m2 stops Dallas/Fort Worth Phoenix Sky Harbor Intl
American Airlines Logo
11:59 pm - 9:18 amONT  Ontario-STL Lambert-St Louis
7h 19m1 stop Dallas/Fort Worth
$362American Airlines
Tue, Oct 27 - Mon, Nov 2
United Airlines Logo
1:08 pm - 9:40 pmSTL  Lambert-St Louis-ONT Ontario
10h 32m2 stops Chicago O'Hare Intl Houston George Bush Intcntl
United Airlines Logo
5:00 am - 12:38 pmONT  Ontario-STL Lambert-St Louis
5h 38m1 stop Denver Intl
$462United Airlines
Tue, Dec 8 - Tue, Dec 15
United Airlines Logo
11:05 am - 8:20 pmSTL  Lambert-St Louis-ONT Ontario
11h 15m2 stops Newark Denver Intl
United Airlines Logo
5:00 am - 12:43 pmONT  Ontario-STL Lambert-St Louis
5h 43m1 stop Denver Intl
$462United 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 $146. 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 $146 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.

  • 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 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.

  • 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.

  • 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.

  • What popular places can I visit in Ontario?

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

  • 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 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 $207, which is 13% above the typical average for this route.

  • 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 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

  • 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.

  • 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.

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
    - Holiday Inn Ontario Airport By IHG

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