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

11 flights are operational weekly from Ontario to Illinois as of September 2025. The most popular departure day for this route is Mon, with 27% of flights per week taking off on this day.

What airlines fly to Illinois?

American Airlines, United Airlines and Spirit Airlines 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 44% of people opting to fly with this airline when traveling to Illinois. Keep in mind that there are 8 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 day?

The number of flights available between Ontario and Illinois is 1 per day as of September 2025. The most frequent departure time is 7:00AM, with 92% of daily flights leaving at noon.

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

Frontier is the most popular carrier 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 September 2025, 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 2025/26

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Find the cheapest flights from Ontario to Illinois

Round-trip

One-way

Last minute

Direct

Cheap round-trip flights

10:30 am - 9:07 amONT-STL

20h 37m1 stop

7:52 pm - 9:35 amSTL-ONT

15h 43m1 stop

$142Frontier

Find Deal

Thu, Oct 16 - Wed, Oct 22

10:30 am - 9:07 amONT-STL

20h 37m1 stop

12:38 pm - 10:05 pmSTL-ONT

11h 27m1 stop

$143Frontier

Find Deal

Thu, Oct 16 - Mon, Oct 20

12:28 pm - 10:45 pmONT-ORD

8h 17m1 stop

6:40 am - 8:42 pmORD-ONT

16h 02m1 stop

$203Multiple Airlines

Find Deal

Fri, Oct 3 - Tue, Oct 7

12:32 pm - 12:44 amONT-ORD

10h 12m1 stop

8:50 pm - 6:42 amORD-ONT

11h 52m1 stop

$206Multiple Airlines

Find Deal

Mon, Oct 27 - Wed, Nov 5

3:08 pm - 10:58 pmONT-STL

5h 50m1 stop

2:29 pm - 6:20 pmSTL-ONT

5h 51m1 stop

$293American Airlines

Find Deal

Tue, Nov 18 - Thu, Nov 20

6:36 pm - 10:13 amONT-PIA

13h 37m2 stops

1:20 pm - 6:36 pmPIA-ONT

7h 16m1 stop

$294United Airlines

Find Deal

Mon, Oct 20 - Tue, Oct 28

9:59 am - 7:30 pmONT-STL

7h 31m2 stops

1:20 pm - 6:21 pmSTL-ONT

7h 01m1 stop

$298American Airlines

Find Deal

Sat, Nov 8 - Tue, Nov 11

7:02 am - 4:43 pmONT-PIA

7h 41m1 stop

5:18 pm - 10:31 pmPIA-ONT

7h 13m1 stop

$350United Airlines

Find Deal

Fri, Oct 24 - Sun, Oct 26

11:36 am - 10:17 pmONT-BMI

8h 41m1 stop

3:30 pm - 11:04 pmBMI-ONT

9h 34m1 stop

$396Delta

Find Deal

Sat, Nov 8 - Mon, Nov 17

10:25 pm - 9:30 amONT-EVV

9h 05m1 stop

5:55 pm - 11:04 pmEVV-ONT

7h 09m1 stop

$439Delta

Find Deal

Wed, Nov 19 - Wed, Nov 26

Frontier flights from Ontario to Illinois

Our best Frontier deals on Ontario to Illinois flight tickets

Frontier

Oct 16

ONT10:30 amOntario

20h 37m

1 stop

STL9:07 amLambert-St Louis

Oct 22

STL7:52 pmLambert-St Louis

15h 43m

1 stop

ONT9:35 amOntario

$142

Find similar

Frontier

Oct 16

ONT10:30 amOntario

20h 37m

1 stop

STL9:07 amLambert-St Louis

Oct 20

STL12:38 pmLambert-St Louis

11h 27m

1 stop

ONT10:05 pmOntario

$143

Find similar

Frontier

Sep 30

ONT8:59 pmOntario

10h 07m

1 stop

STL9:06 amLambert-St Louis

Oct 21

STL7:52 pmLambert-St Louis

5h 58m

1 stop

ONT11:50 pmOntario

$144

Find similar

American Airlines flights from Ontario to Illinois

Our best American Airlines deals on Ontario to Illinois flight tickets

American Airlines

Nov 18

ONT3:08 pmOntario

5h 50m

1 stop

STL10:58 pmLambert-St Louis

Nov 20

STL2:29 pmLambert-St Louis

5h 51m

1 stop

ONT6:20 pmOntario

$293

Find similar

American Airlines

Nov 8

ONT9:59 amOntario

7h 31m

2 stops

STL7:30 pmLambert-St Louis

Nov 11

STL1:20 pmLambert-St Louis

7h 01m

1 stop

ONT6:21 pmOntario

$298

Find similar

American Airlines

Oct 20

ONT11:59 pmOntario

8h 47m

1 stop

PIA10:46 amGreater Peoria

Oct 28

PIA7:00 amGreater Peoria

6h 53m

1 stop

ONT11:53 amOntario

$314

Find similar

Fly from

Fly to

Route

Depart

Return

Price

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

Thu 10/16

10:30 am-9:07 am

1 stop20h 37m

Lambert-St Louis

Wed 10/22

7:52 pm-9:35 am

1 stop15h 43m

$142

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

Thu 10/16

10:30 am-9:07 am

1 stop20h 37m

Lambert-St Louis

Mon 10/20

12:38 pm-10:05 pm

1 stop11h 27m

$143

OntarioChicago

ONT - ORD

ONTORD

Ontario

Fri 10/3

12:28 pm-10:45 pm

1 stop8h 17m

Chicago O'Hare Intl

Tue 10/7

6:40 am-8:42 pm

1 stop16h 02m

$203

OntarioChicago

ONT - ORD

ONTORD

Ontario

Mon 10/27

12:32 pm-12:44 am

1 stop10h 12m

Chicago O'Hare Intl

Wed 11/5

8:50 pm-6:42 am

1 stop11h 52m

$206

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

Tue 11/18

3:08 pm-10:58 pm

1 stop5h 50m

Lambert-St Louis

Thu 11/20

2:29 pm-6:20 pm

1 stop5h 51m

$293

OntarioPeoria

ONT - PIA

ONTPIA

Ontario

Mon 10/20

6:36 pm-10:13 am

2 stops13h 37m

Greater Peoria

Tue 10/28

1:20 pm-6:36 pm

1 stop7h 16m

$294

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

Sat 11/8

9:59 am-7:30 pm

2 stops7h 31m

Lambert-St Louis

Tue 11/11

1:20 pm-6:21 pm

1 stop7h 01m

$298

OntarioPeoria

ONT - PIA

ONTPIA

Ontario

Fri 10/24

7:02 am-4:43 pm

1 stop7h 41m

Greater Peoria

Sun 10/26

5:18 pm-10:31 pm

1 stop7h 13m

$350

OntarioBloomington

ONT - BMI

ONTBMI

Ontario

Sat 11/8

11:36 am-10:17 pm

1 stop8h 41m

Bloomington-Normal

Mon 11/17

3:30 pm-11:04 pm

1 stop9h 34m

$396

OntarioEvansville

ONT - EVV

ONTEVV

Ontario

Wed 11/19

10:25 pm-9:30 am

1 stop9h 05m

Evansville Dress Regional

Wed 11/26

5:55 pm-11:04 pm

1 stop7h 09m

$439

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 November. Flight prices, which tend to average around $245, 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 November, then flying in September is also cheap. Prices for this month can be found on momondo for an average of $287.

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

The cheapest day to depart from Ontario to Illinois is on a Wednesday when prices can be found for as low as $439. Flights from Ontario to Illinois on a Sunday will generally be more expensive and average around $497. 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 afternoon. Flights from Ontario to Illinois during this time can be as low as $276. Flights in the evening are often more expensive with an average ticket price of $609.

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 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 $380 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 $243 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 22% 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	$189
Fastest flight time	3h 45m
Direct flights	Every day
Airports in Illinois	2 airports

The best one-way flight to Illinois from Ontario in the past 72 hours is $189. The best round-trip flight deal from Ontario to Illinois found on momondo in the last 72 hours is $367.

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

Direct flights go from Ontario to Illinois every day.

There are 2 airports near Illinois: Chicago O'Hare Intl (ORD), Chicago Midway (MDW)

Search flight deals

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 September 2025, 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 737-800, representing 18.80% of all bookings. The subsequent popular models are Airbus A321neo at 12.80%, Airbus A318/A319/A320/A321 at 8.72%, and Airbus A320neo at 8.38%.

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 $108	Free Cancellation	Rating 5.8 3,165 reviews	Search Frontier flights
United Airlines	PriceFrom $226	Free Cancellation	Rating 7.4 8,926 reviews	Search United Airlines flights
Delta	PriceFrom $236	Free Cancellation	Rating 7.9 7,974 reviews	Search Delta flights
Southwest	PriceFrom $237	Free Cancellation	Rating 8.0 4,244 reviews	Search Southwest flights
American Airlines	PriceFrom $246	Free Cancellation	Rating 7.2 10,000 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

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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Thu 10/30

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Find better results for your trip to Illinois

Popular cities in Illinois

Flights to New Yorkfrom $50

Flights to Los Angelesfrom $44

Flights to Miamifrom $49

Flights to Chicagofrom $60

Flights to Orlandofrom $56

Flights to Las Vegasfrom $44

Flights to San Franciscofrom $60

Flights to Washington, D.C.from $56

Flights to Bostonfrom $67

Flights to Atlantafrom $51

Flights to Dallasfrom $59

Flights to Seattlefrom $102

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 10/30. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.

Big names and deals

Big names and deals

Filter for what you want

Filter for what you want

Trusted and free

Trusted and free

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Price Alerts

Find the cheapest flights from Ontario to Illinois

Cheap round-trip flights

Cheap one-way flights

Cheap last minute flights

Cheap direct flights

Frontier flights from Ontario to Illinois

Our best Frontier deals on Ontario to Illinois flight tickets

American Airlines flights from Ontario to Illinois

Our best American Airlines deals on Ontario to Illinois flight tickets

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Use the filters below to find and compare flights from Ontario to Illinois that are best for you.

See travel insights to Illinois from

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

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?

Our most recent data shows that the best time of day to fly to Illinois is in the afternoon. Flights from Ontario to Illinois during this time can be as low as $276. Flights in the evening are often more expensive with an average ticket price of $609.

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 to Illinois?

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 22% on your flight if you consider stops on a Ontario to Illinois flight.

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

Frontier is the most popular carrier operating from Ontario to Illinois

What airlines fly to Illinois?

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 September 2025. The most frequent departure time is 7:00AM, with 92% of daily flights leaving at noon.

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

11 flights are operational weekly from Ontario to Illinois as of September 2025. The most popular departure day for this route is Mon, with 27% of flights per week taking off on this day.

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

Fastest flight time

Direct flights

Airports in Illinois

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

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

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

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

What is the most popular plane model 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?

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

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

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

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

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