How many flights depart from Ontario to Illinois on average per day?

The number of flights available between Ontario and Illinois is 1 per day as of August 2026. The most frequent departure time is 11:00PM, with 43% of daily flights leaving in the evening.

What airlines fly to Illinois?

American Airlines, United Airlines and Frontier are the top three most popular airlines that fly to Illinois from Ontario according to our data. American Airlines is the first choice among our users, with 43% of people opting to fly with this airline when traveling to Illinois. Keep in mind that there are 7 different airlines that fly to Illinois on a routine basis, so you have a few additional options to choose from.

How many flights depart from Ontario to Illinois on average per week?

13 flights are operational weekly from Ontario to Illinois as of August 2026. The most popular departure day for this route is Mon, with 15% of flights per week taking off on this day.

What is the cheapest airline that flies from Ontario to Illinois?

Southwest, United Airlines, and Frontier are the most popular carriers operating from Ontario to Illinois

When did momondo last update prices for flights from Ontario Airport to Illinois?

Prices for flights from Ontario Airport to Illinois were last updated today.

How many operators does momondo search for flights from Ontario Airport to Illinois?

As of August 2026, there are 5 operators available to choose from for flights from Ontario Airport to Illinois.

How old do you have to be to fly from Ontario Airport to Illinois?

The minimum age for a child to fly alone is five, but airlines offering an unaccompanied minor (UNMR) service may have their age restrictions, such as regulations concerning flight duration, timing, and layovers. It is recommended that you verify with the airline you are booking with for travel from Ontario Airport to Illinois.

What documentation or ID do you need to fly to Illinois?

The travel and health documents required for your trip to Illinois can vary based on your itinerary and personal situation. As a rule, consider having multiple documents such as a national ID card or driver’s license, and a passport valid for six-months after you plan to arrive at Illinois. We always recommend checking with your airline or a trusted third party such as IATA to get advice.

$72 Cheap Flights from Ontario to Illinois in 2026

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Find the cheapest flights from Ontario to Illinois

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11:45 am - 7:17 pmONT Ontario-STL Lambert-St Louis

5h 32m1 stop Denver Intl

12:17 pm - 4:34 pmSTL Lambert-St Louis-ONT Ontario

6h 17m1 stop Las Vegas Harry Reid Intl

$178Frontier

Wed, Sep 16 - Sat, Sep 26

10:04 am - 11:17 amONT Ontario-STL Lambert-St Louis

23h 13m1 stop Las Vegas Harry Reid Intl

12:17 pm - 4:59 pmSTL Lambert-St Louis-ONT Ontario

6h 42m1 stop Las Vegas Harry Reid Intl

$178Frontier

Wed, Sep 16 - Tue, Sep 22

10:00 pm - 12:39 pmONT Ontario-MDW Chicago Midway

12h 39m2 stops Atlanta Hartsfield-Jackson Detroit Metropolitan Wayne County

6:05 am - 11:05 amMDW Chicago Midway-ONT Ontario

7h 00m1 stop Atlanta Hartsfield-Jackson

$263Delta

Mon, Sep 14 - Wed, Sep 16

6:01 pm - 8:39 amONT Ontario-MDW Chicago Midway

12h 38m2 stops Seattle/Tacoma Intl Minneapolis St Paul

10:56 am - 6:30 pmMDW Chicago Midway-ONT Ontario

9h 34m1 stop Atlanta Hartsfield-Jackson

$263Delta

Mon, Aug 31 - Sat, Sep 5

8:40 am - 7:50 pmONT Ontario-MDW Chicago Midway

9h 10m2 stops Phoenix Sky Harbor Intl Louisville Intl

10:25 am - 12:45 pmMDW Chicago Midway-ONT Ontario

4h 20mnonstop

$266Southwest

Tue, Dec 1 - Sat, Dec 5

6:25 pm - 5:45 amONT Ontario-MDW Chicago Midway

9h 20m1 stop Phoenix Sky Harbor Intl

10:25 am - 12:45 pmMDW Chicago Midway-ONT Ontario

4h 20mnonstop

$266Southwest

Tue, Dec 1 - Sat, Dec 5

7:12 am - 5:10 pmONT Ontario-STL Lambert-St Louis

7h 58m1 stop Portland

8:10 pm - 10:30 amSTL Lambert-St Louis-ONT Ontario

16h 20m1 stop Denver Intl

$270Multiple Airlines

Thu, Sep 24 - Mon, Sep 28

2:22 pm - 11:42 pmONT Ontario-STL Lambert-St Louis

7h 20m1 stop Dallas/Fort Worth

5:40 am - 12:14 pmSTL Lambert-St Louis-ONT Ontario

8h 34m2 stops Dallas/Fort Worth Phoenix Sky Harbor Intl

$272American Airlines

Thu, Oct 15 - Sat, Oct 17

2:27 pm - 12:18 amONT Ontario-ORD Chicago O'Hare Intl

7h 51m1 stop Dallas/Fort Worth

5:00 am - 9:29 amORD Chicago O'Hare Intl-ONT Ontario

6h 29m1 stop Dallas/Fort Worth

$277American Airlines

Tue, Sep 8 - Sun, Sep 13

8:24 pm - 5:38 amONT Ontario-ORD Chicago O'Hare Intl

7h 14m1 stop Las Vegas Harry Reid Intl

6:00 am - 1:16 pmORD Chicago O'Hare Intl-ONT Ontario

9h 16m1 stop Seattle/Tacoma Intl

$278Multiple Airlines

Mon, Oct 5 - Thu, Oct 8

Cheap last minute flights

Enter your travel dates to find the best prices.

2:27 pm - 12:18 amONT Ontario-ORD Chicago O'Hare Intl

7h 51m1 stop Dallas/Fort Worth

6:59 am - 12:03 pmORD Chicago O'Hare Intl-ONT Ontario

7h 04m1 stop Phoenix Sky Harbor Intl

$277American Airlines

Fri, Aug 14 - Tue, Aug 18

1:56 pm - 10:59 pmONT Ontario-ORD Chicago O'Hare Intl

7h 03m1 stop San Francisco

6:00 am - 12:12 pmORD Chicago O'Hare Intl-ONT Ontario

8h 12m1 stop San Francisco

$277United Airlines

Thu, Aug 13 - Tue, Aug 18

1:18 pm - 9:29 pmONT Ontario-ORD Chicago O'Hare Intl

6h 11m1 stop Denver Intl

4:00 pm - 10:59 pmORD Chicago O'Hare Intl-ONT Ontario

8h 59m1 stop San Francisco

$277United Airlines

Fri, Aug 14 - Mon, Aug 17

9:36 am - 12:33 amONT Ontario-ORD Chicago O'Hare Intl

12h 57m1 stop Houston George Bush Intcntl

9:10 pm - 8:36 amORD Chicago O'Hare Intl-ONT Ontario

13h 26m1 stop Dallas/Fort Worth

$282Frontier

Sat, Aug 15 - Tue, Aug 18

6:00 am - 8:52 pmONT Ontario-ORD Chicago O'Hare Intl

12h 52m1 stop Denver Intl

9:34 pm - 8:41 amORD Chicago O'Hare Intl-ONT Ontario

13h 07m1 stop Dallas/Fort Worth

$282Frontier

Sat, Aug 15 - Sun, Aug 16

1:06 pm - 9:33 pmONT Ontario-ORD Chicago O'Hare Intl

6h 27m1 stop Salt Lake City

3:51 pm - 11:34 pmORD Chicago O'Hare Intl-ONT Ontario

9h 43m2 stops Minneapolis St Paul Salt Lake City

$282Delta

Fri, Aug 14 - Mon, Aug 17

10:00 pm - 1:50 pmONT Ontario-ORD Chicago O'Hare Intl

13h 50m2 stops Atlanta Hartsfield-Jackson Detroit Metropolitan Wayne County

7:44 pm - 11:34 pmORD Chicago O'Hare Intl-ONT Ontario

5h 50m1 stop Salt Lake City

$282Delta

Fri, Aug 14 - Wed, Aug 19

4:07 pm - 12:28 amONT Ontario-ORD Chicago O'Hare Intl

6h 21m1 stop Phoenix Sky Harbor Intl

6:59 am - 12:03 pmORD Chicago O'Hare Intl-ONT Ontario

7h 04m1 stop Phoenix Sky Harbor Intl

$377American Airlines

Mon, Aug 17 - Thu, Aug 20

12:50 pm - 11:20 pmONT Ontario-MDW Chicago Midway

8h 30m1 stop Austin Bergstrom

7:10 am - 1:25 pmMDW Chicago Midway-ONT Ontario

8h 15m1 stop Phoenix Sky Harbor Intl

$417Southwest

Fri, Aug 14 - Mon, Aug 17

12:50 pm - 11:20 pmONT Ontario-MDW Chicago Midway

8h 30m2 stops Austin Bergstrom Dallas Love Field

7:10 am - 1:25 pmMDW Chicago Midway-ONT Ontario

8h 15m1 stop Phoenix Sky Harbor Intl

$422Southwest

Fri, Aug 14 - Mon, Aug 17

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United Airlines flights from Ontario to Illinois

Our best United Airlines deals on Ontario to Illinois flight tickets

United Airlines

Aug 26

ONT5:00 amOntario

8h 00m

1 stop

ORD3:00 pmChicago O'Hare Intl

Aug 29

ORD8:06 pmChicago O'Hare Intl

4h 29m

ONT10:35 pmOntario

$267

United Airlines

Nov 13

ONT7:00 amOntario

4h 10m

ORD1:10 pmChicago O'Hare Intl

Nov 15

ORD6:00 amChicago O'Hare Intl

8h 29m

1 stop

ONT12:29 pmOntario

$270

United Airlines

Sep 16

ONT1:18 pmOntario

6h 42m

1 stop

ORD10:00 pmChicago O'Hare Intl

Sep 18

ORD8:33 pmChicago O'Hare Intl

4h 26m

ONT10:59 pmOntario

$271

Frontier flights from Ontario to Illinois

Our best Frontier deals on Ontario to Illinois flight tickets

Frontier

Sep 16

ONT10:04 amOntario

23h 13m

1 stop

STL11:17 amLambert-St Louis

Sep 22

STL12:17 pmLambert-St Louis

6h 42m

1 stop

ONT4:59 pmOntario

$178

Frontier

Sep 29

ONT5:44 pmOntario

15h 48m

1 stop

STL11:32 amLambert-St Louis

Oct 3

STL8:10 pmLambert-St Louis

5h 37m

1 stop

ONT11:47 pmOntario

$184

Frontier

Oct 20

ONT11:16 amOntario

12h 01m

1 stop

STL1:17 amLambert-St Louis

Oct 24

STL8:10 pmLambert-St Louis

5h 45m

1 stop

ONT11:55 pmOntario

$188

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

Quickest round-trip

OntarioSt. Louis

ONT Ontario - STL Lambert-St Louis

ONTSTL

Ontario

Wed 9/16

11:45 am-7:17 pm

1 stop5h 32m

Lambert-St Louis

Sat 9/26

12:17 pm-4:34 pm

1 stop6h 17m

$178

OntarioSt. Louis

ONT Ontario - STL Lambert-St Louis

ONTSTL

Ontario

Wed 9/16

10:04 am-11:17 am

1 stop23h 13m

Lambert-St Louis

Tue 9/22

12:17 pm-4:59 pm

1 stop6h 42m

$178

OntarioChicago

ONT Ontario - MDW Chicago Midway

ONTMDW

Ontario

Mon 9/14

10:00 pm-12:39 pm

2 stops12h 39m

Chicago Midway

Wed 9/16

6:05 am-11:05 am

1 stop7h 00m

$263

OntarioChicago

ONT Ontario - MDW Chicago Midway

ONTMDW

Ontario

Mon 8/31

6:01 pm-8:39 am

2 stops12h 38m

Chicago Midway

Sat 9/5

10:56 am-6:30 pm

1 stop9h 34m

$263

OntarioChicago

ONT Ontario - MDW Chicago Midway

ONTMDW

Ontario

Tue 12/1

8:40 am-7:50 pm

2 stops9h 10m

Chicago Midway

Sat 12/5

10:25 am-12:45 pm

Nonstop4h 20m

$266

OntarioChicago

ONT Ontario - MDW Chicago Midway

ONTMDW

Ontario

Tue 12/1

6:25 pm-5:45 am

1 stop9h 20m

Chicago Midway

Sat 12/5

10:25 am-12:45 pm

Nonstop4h 20m

$266

OntarioSt. Louis

ONT Ontario - STL Lambert-St Louis

ONTSTL

Ontario

Thu 9/24

7:12 am-5:10 pm

1 stop7h 58m

Lambert-St Louis

Mon 9/28

8:10 pm-10:30 am

1 stop16h 20m

$270

OntarioSt. Louis

ONT Ontario - STL Lambert-St Louis

ONTSTL

Ontario

Thu 10/15

2:22 pm-11:42 pm

1 stop7h 20m

Lambert-St Louis

Sat 10/17

5:40 am-12:14 pm

2 stops8h 34m

$272

OntarioChicago

ONT Ontario - ORD Chicago O'Hare Intl

ONTORD

Ontario

Tue 9/8

2:27 pm-12:18 am

1 stop7h 51m

Chicago O'Hare Intl

Sun 9/13

5:00 am-9:29 am

1 stop6h 29m

$277

OntarioChicago

ONT Ontario - ORD Chicago O'Hare Intl

ONTORD

Ontario

Mon 10/5

8:24 pm-5:38 am

1 stop7h 14m

Chicago O'Hare Intl

Thu 10/8

6:00 am-1:16 pm

1 stop9h 16m

$278

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 20 resultsSorted by cheapest first

How to get the cheapest flight ticket from Ontario to Illinois

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

Prices

Airlines

Other information

What is the cheapest month to fly to Illinois?

The cheapest month to fly to Illinois from Ontario is in January. Flight prices, which tend to average around $345, are often lower during this time because this is during the off-season. If you aren’t able to travel to Illinois during the month of January, then flying in September is also cheap. Prices for this month can be found on momondo for an average of $363.

What is the cheapest day to depart on your flight to Illinois?

The cheapest day to depart from Ontario to Illinois is on a Tuesday when prices can be found for as low as $454. Flights from Ontario to Illinois on a Sunday will generally be more expensive and average around $555. Keep in mind that these prices on both days could fluctuate depending on the season and the demand.

What is the cheapest time of day to depart on your flight to Illinois?

Our most recent data shows that the best time of day to fly to Illinois is in the evening. Flights from Ontario to Illinois during this time can be as low as $482. Flights at noon are often more expensive with an average ticket price of $526.

What is the cheapest Ontario to Illinois flight route?

Fly from Ontario to Chicago Midway for the best Ontario - Illinois flight prices

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

You are more likely to see cheaper flights to Illinois from Ontario when booking weeks ahead of your departure date. In general, you can expect to find flights to Illinois for around $421 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Illinois from Ontario for as low as $345 on momondo.

What cabin class options are available on Ontario to Illinois flights?

There are 4 cabin classes available to choose from on Ontario to Illinois flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Can stopping save me money on Ontario to Illinois flights?

You could potentially save up to 15% on your flight if you consider stops on a Ontario to Illinois flight.

Cheap Ontario to Illinois flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from Ontario to Illinois

Best Price Found	$193
Fastest flight time	3h 45m
Direct flights	Every day
Airports in Illinois	98 airports

The best one-way flight to Illinois from Ontario in the past 72 hours is $193. The best round-trip flight deal from Ontario to Illinois found on momondo in the last 72 hours is $380.

The fastest flight from Ontario to Illinois takes 3h 45m

Direct flights go from Ontario to Illinois every day.

There are 98 airports in Illinois. From Ontario there are direct flights to Chicago O'Hare Intl (ORD), Chicago Midway (MDW).

Search flight deals

Frequently asked questions about flying from Ontario to Illinois

When did momondo last update prices for flights from Ontario Airport to Illinois?
Prices for flights from Ontario Airport to Illinois were last updated today.
How many operators does momondo search for flights from Ontario Airport to Illinois?
As of August 2026, there are 5 operators available to choose from for flights from Ontario Airport to Illinois.
How old do you have to be to fly from Ontario Airport to Illinois?
The minimum age for a child to fly alone is five, but airlines offering an unaccompanied minor (UNMR) service may have their age restrictions, such as regulations concerning flight duration, timing, and layovers. It is recommended that you verify with the airline you are booking with for travel from Ontario Airport to Illinois.
What documentation or ID do you need to fly to Illinois?
The travel and health documents required for your trip to Illinois can vary based on your itinerary and personal situation. As a rule, consider having multiple documents such as a national ID card or driver’s license, and a passport valid for six-months after you plan to arrive at Illinois. We always recommend checking with your airline or a trusted third party such as IATA to get advice.
What is the most popular plane model from Ontario to Illinois?
momondo data reveals that the most frequently booked plane model on the route from Ontario to Illinois is Boeing 737 MAX 8, representing 16.55% of all bookings. The subsequent popular models are Boeing 737-900 at 16.45%, Boeing 737-800 at 12.54%, and Airbus A321neo at 12.04%.

Best airlines flying from Ontario to Illinois

Compare and see reviews for airlines that fly from Ontario to Illinois with momondo

Airline	Rating	Free Cancellation	Price
Frontier	PriceFrom $131	Free Cancellation	Rating 5.6 2,701 reviews	Search Frontier flights
Southwest	PriceFrom $255	Free Cancellation	Rating 8.0 4,220 reviews	Search Southwest flights
Delta	PriceFrom $258	Free Cancellation	Rating 7.8 8,505 reviews	Search Delta flights
United Airlines	PriceFrom $268	Free Cancellation	Rating 7.4 10,111 reviews	Search United Airlines flights
American Airlines	PriceFrom $288	Free Cancellation	Rating 7.1 11,911 reviews	Search American Airlines flights

Why use momondo?

Why should I use momondo to find a flight deal from Ontario to Illinois?

momondo collates all your flight options in one place and lets you filter them to find the perfect flight from Ontario to Illinois. momondo saves you time and could save you money on your trip.

Can I find flights from Ontario to Illinois with flexible booking policies on momondo?

Flights from Ontario to Illinois with flexible booking policies can be found by using the search form above and then selecting our dedicated flexible booking filter, which will highlight only the flights where this policy is applied.

How can momondo help me find flights from Ontario to Illinois?

Once you have performed a search for Ontario to Illinois flights, momondo helps you find the right one by offering useful filters to narrow down your flight selection. Flights can be filtered by multiple factors such as airline, airport and price; but also by other criteria like aircraft type and payment method.

I’m not ready to book a flight from Ontario to Illinois right now. Can momondo alert me if prices change?

If you are simply researching potential flights to Illinois, momondo offers a useful price alert feature which will track prices for flights to Illinois from Ontario and alert you when they change.

An easier way to manage your Illinois trip

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Popular cities in Illinois

Flights to New Yorkfrom $82

Flights to Los Angelesfrom $50

Flights to Orlandofrom $46

Flights to Miamifrom $79

Flights to San Franciscofrom $46

Flights to Chicagofrom $56

Flights to Las Vegasfrom $59

Flights to Washington, D.C.from $74

Flights to Bostonfrom $72

Flights to Atlantafrom $51

Flights to Fort Lauderdalefrom $56

Flights to Dallasfrom $63

Cheap flights from Ontario to Illinois from $72

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from Ontario to Illinois departing on 9/24. 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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United Airlines flights from Ontario to Illinois

Our best United Airlines deals on Ontario to Illinois flight tickets

Frontier flights from Ontario to Illinois

Our best Frontier deals on Ontario to Illinois flight tickets

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See travel insights to Illinois from

How to get the cheapest flight ticket from Ontario to Illinois

What is the cheapest month to fly to Illinois?

What is the cheapest day to depart on your flight to Illinois?

What is the cheapest time of day to depart on your flight to Illinois?

What is the cheapest Ontario to Illinois flight route?

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

What cabin class options are available on Ontario to Illinois flights?

Can stopping save me money on Ontario to Illinois flights?

What is the cheapest airline that flies from Ontario to Illinois?

What airlines fly to Illinois?

How many flights depart from Ontario to Illinois on average per day?

How many flights depart from Ontario to Illinois on average per week?

Cheap Ontario to Illinois flight deals and tips

Best Price Found

Fastest flight time

Direct flights

Airports in Illinois

Frequently asked questions about flying from Ontario to Illinois

Best airlines flying from Ontario to Illinois

Compare and see reviews for airlines that fly from Ontario to Illinois with momondo

Why use momondo?

An easier way to manage your Illinois 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.

Get notified when prices go down

Daily price changes in your inbox - only with Price Alerts.

Find better results for your trip to Illinois

Popular cities in Illinois

Popular flights according to clicks in the last 7 days on momondo

Ontario flight routes

According to popular flight searches on momondo this year

Illinois flight routes

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