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

Frontier, Alaska Airlines, and Delta are the most popular carriers operating from Illinois to Ontario

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

As of January 2026, 2 flights take off from Illinois and land in Ontario each day. The most common flight departure time for this route is 8:00AM, with 50% of daily flights taking off at noon.

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

14 flights are operational weekly from Illinois to Ontario as of January 2026. The most popular departure day for this route is Mon, with 29% of flights per week taking off on this day.

What airlines fly to Ontario?

American Airlines, United Airlines and Spirit Airlines are the top three most popular airlines that fly to Ontario from Illinois 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 Ontario. Keep in mind that there are 8 different airlines that fly to Ontario on a routine basis, so you have a few additional options to choose from.

How long does it take to fly to Ontario?

Average flight duration from Illinois to Ontario depends on which airport you fly into and out of. Flying from Chicago to Los Angeles is 4h 15m on average, while flying from Moline to Los Angeles is 6h 37m on average. Los Angeles is the most popular airport in Ontario.

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

Prices for flights from Illinois to Ontario Airport refresh daily.

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

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

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

The minimum age for a child to fly alone is five, but airlines that offer an unaccompanied minor (UNMR) service may have their own age limitations. Flight duration, scheduling, and layovers are among the considerations that may influence age limits. We recommend that you double-check with the airline you are booking with for travel from Illinois to Ontario Airport.

What documentation or ID do you need to fly to Ontario Airport?

The travel and health documents required for your trip to Ontario Airport 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 Ontario Airport. We always recommend checking with your airline or a trusted third party such as IATA to get advice.

$61 Cheap Flights from Illinois to Ontario in 2026

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Find the cheapest flights from Illinois to Los Angeles

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Cheap round-trip flights

Enter your travel dates to find the best prices.

10:11 pm - 1:11 pm

STL

ONT

17h 00m

1 stop

10:14 pm - 9:13 pm

ONT

STL

20h 59m

1 stop

$158Frontier

Fri, Feb 27 - Sun, Mar 1

10:53 am - 11:59 pm

ORD

ONT

15h 06m

1 stop

4:49 pm - 6:08 am

ONT

ORD

11h 19m

1 stop

$161Frontier

Thu, Mar 12 - Tue, Mar 17

4:51 pm - 9:34 pm

STL

ONT

6h 43m

1 stop

6:00 am - 1:56 pm

ONT

STL

5h 56m

1 stop

$164Frontier

Wed, Feb 18 - Sat, Feb 21

2:51 pm - 7:59 am

STL

ONT

19h 08m

1 stop

6:00 am - 1:56 pm

ONT

STL

5h 56m

1 stop

$165Frontier

Sat, Feb 21 - Sat, Feb 28

6:00 am - 12:02 pm

MDW

ONT

8h 02m

1 stop

1:15 pm - 10:31 pm

ONT

MDW

7h 16m

1 stop

$301Delta

Wed, Feb 18 - Wed, Feb 25

11:00 am - 6:15 pm

MLI

ONT

9h 15m

1 stop

10:59 pm - 10:26 am

ONT

MLI

9h 27m

1 stop

$309Delta

Mon, Jun 1 - Fri, Jun 12

3:58 pm - 10:48 pm

MLI

ONT

8h 50m

1 stop

2:39 pm - 10:53 pm

ONT

MLI

6h 14m

1 stop

$334American Airlines

Fri, Feb 6 - Fri, Feb 20

3:58 pm - 10:48 pm

MLI

ONT

8h 50m

1 stop

9:53 am - 11:37 pm

ONT

MLI

11h 44m

2 stops

$339American Airlines

Fri, Feb 6 - Fri, Feb 20

3:25 pm - 10:18 pm

MLI

ONT

8h 53m

1 stop

11:59 pm - 10:09 am

ONT

MLI

8h 10m

1 stop

$399United Airlines

Mon, Mar 9 - Tue, Mar 17

5:40 pm - 10:26 pm

MLI

ONT

6h 46m

1 stop

10:43 am - 10:45 pm

ONT

MLI

10h 02m

2 stops

$404United Airlines

Tue, Apr 21 - Sat, May 2

Frontier flights from Illinois to Ontario

Our best Frontier deals on Illinois to Ontario flight tickets

Frontier

Feb 27

STL10:11 pmLambert-St Louis

17h 00m

1 stop

ONT1:11 pmOntario

Mar 1

ONT10:14 pmOntario

20h 59m

1 stop

STL9:13 pmLambert-St Louis

$158

Frontier

Mar 12

ORD10:53 amChicago O'Hare Intl

15h 06m

1 stop

ONT11:59 pmOntario

Mar 17

ONT4:49 pmOntario

11h 19m

1 stop

ORD6:08 amChicago O'Hare Intl

$161

Frontier

Feb 18

STL4:51 pmLambert-St Louis

6h 43m

1 stop

ONT9:34 pmOntario

Feb 21

ONT6:00 amOntario

5h 56m

1 stop

STL1:56 pmLambert-St Louis

$164

Southwest flights from Illinois to Ontario

Our best Southwest deals on Illinois to Ontario flight tickets

Southwest

Feb 24

MDW8:10 amChicago Midway

4h 30m

ONT10:40 amOntario

Feb 26

ONT12:40 pmOntario

3h 45m

MDW6:25 pmChicago Midway

$366

Southwest

Feb 24

MDW11:10 amChicago Midway

6h 55m

1 stop

ONT4:05 pmOntario

Feb 26

ONT12:40 pmOntario

3h 45m

MDW6:25 pmChicago Midway

$372

Southwest

Mar 5

MDW11:50 amChicago Midway

4h 20m

ONT2:10 pmOntario

Mar 10

ONT9:55 pmOntario

7h 50m

1 stop

MDW7:45 amChicago Midway

$376

Fly from

Fly to

Route

Depart

Return

Price

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Fri 2/27

10:11 pm-1:11 pm

1 stop17h 00m

Ontario

Sun 3/1

10:14 pm-9:13 pm

1 stop20h 59m

$158

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Thu 3/12

10:53 am-11:59 pm

1 stop15h 06m

Ontario

Tue 3/17

4:49 pm-6:08 am

1 stop11h 19m

$161

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Wed 2/18

4:51 pm-9:34 pm

1 stop6h 43m

Ontario

Sat 2/21

6:00 am-1:56 pm

1 stop5h 56m

$164

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Sat 2/21

2:51 pm-7:59 am

1 stop19h 08m

Ontario

Sat 2/28

6:00 am-1:56 pm

1 stop5h 56m

$165

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

Wed 2/18

6:00 am-12:02 pm

1 stop8h 02m

Ontario

Wed 2/25

1:15 pm-10:31 pm

1 stop7h 16m

$301

MolineOntario

MLI - ONT

MLIONT

Moline Quad-City

Mon 6/1

11:00 am-6:15 pm

1 stop9h 15m

Ontario

Fri 6/12

10:59 pm-10:26 am

1 stop9h 27m

$309

MolineOntario

MLI - ONT

MLIONT

Moline Quad-City

Fri 2/6

3:58 pm-10:48 pm

1 stop8h 50m

Ontario

Fri 2/20

2:39 pm-10:53 pm

1 stop6h 14m

$334

MolineOntario

MLI - ONT

MLIONT

Moline Quad-City

Fri 2/6

3:58 pm-10:48 pm

1 stop8h 50m

Ontario

Fri 2/20

9:53 am-11:37 pm

2 stops11h 44m

$339

MolineOntario

MLI - ONT

MLIONT

Moline Quad-City

Mon 3/9

3:25 pm-10:18 pm

1 stop8h 53m

Ontario

Tue 3/17

11:59 pm-10:09 am

1 stop8h 10m

$399

MolineOntario

MLI - ONT

MLIONT

Moline Quad-City

Tue 4/21

5:40 pm-10:26 pm

1 stop6h 46m

Ontario

Sat 5/2

10:43 am-10:45 pm

2 stops10h 02m

$404

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How to get the cheapest flight ticket from Illinois to Ontario

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 Ontario?

In general, October is the cheapest month to fly from Illinois to Ontario. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $245. If you aren’t able to travel during the month of October, then book flights to Ontario from Illinois during March instead. Flights to Ontario in March, while not as cheap as those in October, still average around $310.

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

The cheapest day to depart on your flight to Ontario is on a Sunday when prices can be found for as low as $382. This is often the case because there is less demand to fly during this day of the week. When flying out on a Saturday, the most expensive travel day of the week, you can expect to see flight prices from Illinois to Ontario for around $499.

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

At noon is the cheapest time of day to fly from Illinois to Ontario when you can find flight prices for as low as $379. Flying to Ontario at noon is an ideal time because this is during off-peak travel hours. If you have a flexible travel schedule, then try to avoid flying in the morning when prices are $502 on average. Flights to Ontario from Illinois in the morning are generally more expensive because this time of day is more convenient for travelers’ schedules.

What is the cheapest Illinois to Ontario flight route?

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

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

You are more likely to see cheaper flights to Ontario from Illinois when booking weeks ahead of your departure date. In general, you can expect to find flights to Ontario for around $366 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Ontario from Illinois for as low as $227 on momondo.

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

There are 4 cabin classes available to choose from on Illinois to Ontario 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 Illinois to Ontario flights?

You could potentially save up to 52% on your flight if you consider stops on a Illinois to Ontario flight.

Cheap Illinois to Ontario flight deals and tips

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

Best Price Found	$300
Fastest flight time	4h 05m
Direct flights	Every day
Airports in Ontario	1 airport

The best one-way flight to Ontario from Illinois in the past 72 hours is $300. The best round-trip flight deal from Illinois to Ontario found on momondo in the last 72 hours is $442.

The fastest flight from Illinois to Ontario takes 4h 05m

Direct flights go from Illinois to Ontario every day.

There is 1 airport in Ontario. From Illinois there are direct flights to Ontario (ONT).

Search flight deals

When did momondo last update prices for flights from Illinois to Ontario Airport?
Prices for flights from Illinois to Ontario Airport refresh daily.
How many operators does momondo search for flights from Illinois to Ontario Airport?
As of January 2026, there are 5 operators available to choose from for flights from Illinois to Ontario Airport.
How old do you have to be to fly from Illinois to Ontario Airport?
The minimum age for a child to fly alone is five, but airlines that offer an unaccompanied minor (UNMR) service may have their own age limitations. Flight duration, scheduling, and layovers are among the considerations that may influence age limits. We recommend that you double-check with the airline you are booking with for travel from Illinois to Ontario Airport.
What documentation or ID do you need to fly to Ontario Airport?
The travel and health documents required for your trip to Ontario Airport 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 Ontario Airport. 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 Illinois to Ontario?
momondo data reveals that the most frequently booked plane model on the route from Illinois to Ontario is Airbus A321neo, representing 14.18% of all bookings. The subsequent popular models are Boeing 737-800 at 12.69%, Boeing 737 MAX 8 at 11.94%, and Boeing 757-300 at 7.46%.

Best airlines flying from Illinois to Ontario

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

Airline	Rating	Free Cancellation	Price
Frontier	PriceFrom $125	Free Cancellation	Rating 5.7 3,057 reviews	Search Frontier flights
American Airlines	PriceFrom $231	Free Cancellation	Rating 7.2 11,174 reviews	Search American Airlines flights
United Airlines	PriceFrom $237	Free Cancellation	Rating 7.4 9,191 reviews	Search United Airlines flights
Southwest	PriceFrom $246	Free Cancellation	Rating 8.0 4,266 reviews	Search Southwest flights
Delta	PriceFrom $256	Free Cancellation	Rating 7.9 8,089 reviews	Search Delta flights

Why use momondo?

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

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

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

All flight searches from Illinois to Ontario on momondo can be filtered to show those which offer flexible booking policies.

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

Once all potential Illinois to Ontario flight options are in front of you, momondo lets you sort and filter flights based on preferences such as airline, price and flight times amongst many other options.

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

Price alerts on flights to Ontario from Illinois are quick and easy to set up on momondo. Simply perform a search and select the price alert feature. It is as simple as that.

An easier way to manage your Ontario trip

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Cheap flights from Illinois to Los Angeles from $61

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from Illinois to Los Angeles departing on 4/1. 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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Frontier flights from Illinois to Ontario

Our best Frontier deals on Illinois to Ontario flight tickets

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Our best Southwest deals on Illinois to Ontario flight tickets

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

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How to get the cheapest flight ticket from Illinois to Ontario

What is the cheapest month to fly to Ontario?

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

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

What is the cheapest Illinois to Ontario flight route?

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

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

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

There are 4 cabin classes available to choose from on Illinois to Ontario 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 Illinois to Ontario flights?

You could potentially save up to 52% on your flight if you consider stops on a Illinois to Ontario flight.

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

Frontier, Alaska Airlines, and Delta are the most popular carriers operating from Illinois to Ontario

What airlines fly to Ontario?

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

As of January 2026, 2 flights take off from Illinois and land in Ontario each day. The most common flight departure time for this route is 8:00AM, with 50% of daily flights taking off at noon.

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

14 flights are operational weekly from Illinois to Ontario as of January 2026. The most popular departure day for this route is Mon, with 29% of flights per week taking off on this day.

How long does it take to fly to Ontario?

Average flight duration from Illinois to Ontario depends on which airport you fly into and out of. Flying from Chicago to Los Angeles is 4h 15m on average, while flying from Moline to Los Angeles is 6h 37m on average. Los Angeles is the most popular airport in Ontario.

Cheap Illinois to Ontario flight deals and tips

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

Best Price Found

Fastest flight time

Direct flights

Airports in Ontario

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

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

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

What documentation or ID do you need to fly to Ontario Airport?

What is the most popular plane model from Illinois to Ontario?

Best airlines flying from Illinois to Ontario

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

Why use momondo?

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

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

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

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

An easier way to manage your Ontario 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 the United States

Airports servicing California