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Ontario

$53+ Cheap flights from Illinois to Ontario (ONT)

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 9/4. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — ONT
Jul 8 — Jul 151
Tue 7/8
Tue 7/15
1 adult, Economy
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Cheap flight deals from Illinois to Ontario

Keep the following information in mind while searching for Illinois to Ontario flight deals. Data was last updated July 3, 2025.

Round-trip from

$114
(Priceline)

One-way from

$53
(Priceline)

Popular in

December

Cheapest in

September

Average price

$282

Good round-trip deal

$502 or less

Good one-way deal

$198 or less
From Illinois to Ontario
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One-way flight from Illinois to Ontario
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Highest demand for flights based on searches. 9% potential increase in price ($28 potential increase over avg. RT price).
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Cheapest flight prices on average. 3% potential price decrease ($10 potential savings vs. average RT price).
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Average for round-trip flights in July 2025
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Price to beat on a round-trip flight from Illinois to Ontario.
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Price to beat on a one-way flight from Illinois to Ontario.
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Find flight deals from Illinois to Ontario

Cheapest flights from Illinois to Ontario
Explore the most affordable flight options available from Illinois to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on July 3, 2025.

This Priceline deal was found by Cheapflights users on 7/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/1810:18 amMDW - ONT
1 stop7h 06mFrontier
Mon 9/2212:19 pmONT - MDW
1 stop6h 33mFrontier
Deal found 7/2$114
This Mytrip deal was found by Cheapflights users on 7/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 7/289:56 pmORD - ONT
1 stop20h 24mFrontier
Sat 8/25:13 pmONT - ORD
1 stop25h 53mFrontier
Deal found 7/2$122
This Priceline deal was found by Cheapflights users on 7/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/257:54 pmSTL - ONT
1 stop5h 56mFrontier
Wed 8/2712:59 amONT - STL
1 stop6h 12mFrontier
Deal found 7/2$138
This American Airlines deal was found by Cheapflights users on 7/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/284:51 pmPIA - ONT
1 stop7h 51mAmerican Airlines
Wed 11/512:53 pmONT - PIA
1 stop5h 39mAmerican Airlines
Deal found 7/3$289
This Delta deal was found by Cheapflights users on 7/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/174:59 pmMLI - ONT
1 stop7h 24mDelta
Tue 9/2311:55 amONT - MLI
1 stop8h 47mDelta
Deal found 7/1$289
This United Airlines deal was found by Cheapflights users on 7/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/83:39 pmPIA - ONT
1 stop8h 27mUnited Airlines
Tue 8/127:00 amONT - PIA
1 stop7h 43mUnited Airlines
Deal found 7/2$379
This United Airlines deal was found by Cheapflights users on 7/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/203:40 pmMLI - ONT
1 stop8h 50mUnited Airlines
Tue 9/237:00 amONT - MLI
1 stop7h 54mUnited Airlines
Deal found 7/1$379
This American Airlines deal was found by Cheapflights users on 7/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/316:00 amMLI - ONT
1 stop7h 56mAmerican Airlines
Mon 8/47:05 pmONT - MLI
2 stops18h 44mAmerican Airlines
Deal found 7/1$427
This American Airlines deal was found by Cheapflights users on 6/30. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 7/283:51 pmBMI - ONT
1 stop8h 19mAmerican Airlines
Wed 8/66:10 amONT - BMI
1 stop7h 11mAmerican Airlines
Deal found 6/30$433
This American Airlines deal was found by Cheapflights users on 7/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/53:20 pmCMI - ONT
1 stop9h 14mAmerican Airlines
Tue 8/1210:50 amONT - CMI
1 stop7h 52mAmerican Airlines
Deal found 7/3$434
This Delta deal was found by Cheapflights users on 7/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/75:41 pmEVV - ONT
1 stop6h 46mDelta
Sun 8/1010:05 pmONT - EVV
1 stop9h 28mDelta
Deal found 7/2$467
This Alaska Airlines deal was found by Cheapflights users on 7/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/1810:51 amMLI - ONT
2 stops15h 12mAlaska Airlines
Mon 9/227:47 pmONT - MLI
2 stops13h 03mAlaska Airlines
Deal found 7/1$479

Cheapflights Fare Finder

Customize your flight search to find flights from Illinois to Ontario that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated July 3, 2025.
Use the filters below to find and compare flights from Illinois to Ontario that are best for you.

Fly from

Illinois

Fly to

Ontario

Route

Depart

Return

Price

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

Thu 9/18

10:18 am-3:24 pm

1 stop7h 06m

Ontario

Mon 9/22

12:19 pm-8:52 pm

1 stop6h 33m

$114

ChicagoOntario

ORD - ONT

ORDONT

Chicago O'Hare Intl

Mon 7/28

9:56 pm-4:20 pm

1 stop20h 24m

Ontario

Sat 8/2

5:13 pm-9:06 pm

1 stop25h 53m

$122

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

Mon 8/25

7:54 pm-11:50 pm

1 stop5h 56m

Ontario

Wed 8/27

12:59 am-9:11 am

1 stop6h 12m

$138

PeoriaOntario

PIA - ONT

PIAONT

Greater Peoria

Tue 10/28

4:51 pm-10:42 pm

1 stop7h 51m

Ontario

Wed 11/5

12:53 pm-8:32 pm

1 stop5h 39m

$289

MolineOntario

MLI - ONT

MLIONT

Moline Quad-City

Wed 9/17

4:59 pm-10:23 pm

1 stop7h 24m

Ontario

Tue 9/23

11:55 am-10:42 pm

1 stop8h 47m

$289

PeoriaOntario

PIA - ONT

PIAONT

Greater Peoria

Fri 8/8

3:39 pm-10:06 pm

1 stop8h 27m

Ontario

Tue 8/12

7:00 am-4:43 pm

1 stop7h 43m

$379

MolineOntario

MLI - ONT

MLIONT

Moline Quad-City

Sat 9/20

3:40 pm-10:30 pm

1 stop8h 50m

Ontario

Tue 9/23

7:00 am-4:54 pm

1 stop7h 54m

$379

MolineOntario

MLI - ONT

MLIONT

Moline Quad-City

Thu 7/31

6:00 am-11:56 am

1 stop7h 56m

Ontario

Mon 8/4

7:05 pm-3:49 pm

2 stops18h 44m

$427

BloomingtonOntario

BMI - ONT

BMIONT

Bloomington-Normal

Mon 7/28

3:51 pm-10:10 pm

1 stop8h 19m

Ontario

Wed 8/6

6:10 am-3:21 pm

1 stop7h 11m

$433

ChampaignOntario

CMI - ONT

CMIONT

Champaign University-Willard

Tue 8/5

3:20 pm-10:34 pm

1 stop9h 14m

Ontario

Tue 8/12

10:50 am-8:42 pm

1 stop7h 52m

$434

Flights are sorted by cheapest round-trip flights first.

Deals found on 7/2

Showing 1-10 of 33 results
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Best time to book a flight from Illinois to Ontario

Have a flexible travel schedule? Discover the best time to fly to Ontario from Illinois with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from Illinois to Ontario

What is the cheapest month to book a flight from Illinois to Ontario?

Currently, August is the cheapest month in which you can book a flight from Illinois to Ontario (average of $246). Flying from Illinois to Ontario in March is currently the most expensive (average of $328). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

What is the cheapest time of day to fly from IL to ONT?

Find hourly flight availability from Illinois to Ontario. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated July 3, 2025.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Illinois to Ontario as you normally would.

How much does it cost to fly round-trip from Illinois to Ontario?

Reviews of airlines servicing Ontario

Get insights into the airlines that provide service to Ontario. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Ontario. Reviews last updated July 3, 2025.
See what other customers who have flown with Alaska Airlines, Southwest, and Delta from Illinois to Ontario have to say. Users can see the overall rating for each airline as well as how each is rated in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Food

7.1

Entertainment

7.1

Comfort

7.8

Boarding

8.1

Overall

8.0

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Alaska Airlines
8.0
Very good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Food

7.1

Entertainment

7.1

Comfort

7.8

Boarding

8.1

Overall

8.0

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Southwest
8.0
Very good
4,270 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Food

7.1

Entertainment

7.1

Comfort

7.8

Boarding

8.1

Overall

8.0

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Delta
8.0
Very good
7,970 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Food

7.1

Entertainment

7.1

Comfort

7.8

Boarding

8.1

Overall

8.0

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Hawaiian Airlines
7.8
Good
2,545 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Food

7.1

Entertainment

7.1

Comfort

7.8

Boarding

8.1

Overall

8.0

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
United Airlines
7.4
Good
8,845 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Food

7.1

Entertainment

7.1

Comfort

7.8

Boarding

8.1

Overall

8.0

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.

Related info for your journey

Find useful and relevant information for your journey from Illinois to Ontario. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airport do you fly into for flights to Ontario from Illinois?

    Located just 3.1 mi from the city center, Ontario (ONT) is the airport most travelers will use when flying to Ontario from Illinois.

  • What are the cheapest airlines to fly from Illinois to Ontario one-way?

    $53 is the cheapest one-way deal found within the past few days, from Frontier. You may also be able to find cheap deals on Southwest and Alaska Airlines, with prices starting from $149 and $157, respectively.

  • What are the most popular routes from Illinois to Ontario?

    When deciding which route to take from Illinois to Ontario consider Chicago O'Hare Intl - Ontario, Chicago Midway - Ontario or Lambert-St Louis - Ontario as they are the most popular.

  • What are the cheapest flights from Illinois to Ontario?

    The cheapest flight price from Illinois to Ontario is $135. On average you can expect to pay $456. The most popular route, (Chicago O'Hare Intl - Ontario), can usually be booked for $217.

  • Can I find deals for flights from Illinois to Ontario that include hotel bookings?

    Yes. In addition to deals on Illinois to Ontario flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Illinois to Ontario?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Illinois to Ontario.

  • Can I find deals for business class flights from Illinois to Ontario?

    Yes. Cheapflights offers flight deals from Illinois to Ontario by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from Illinois to Ontario?

    Currently, August is the cheapest month in which you can book a flight from Illinois to Ontario (average of $246). Flying from Illinois to Ontario in March is currently the most expensive (average of $328). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

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Alternative routes for Illinois to Ontario

See prices for flight routes from nearby airports that may be better suited for you.
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Top 5 airlines flying from Illinois to Ontario

Discover the top 5 airlines that operate flights from Illinois to Ontario. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated July 3, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$122Average$199FlexibilityNo cancel feeOn-time62%
American AirlinesCheapest$231Average$563FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$237Average$398FlexibilityNo cancel feeOn-time69%
DeltaCheapest$246Average$283FlexibilityNo cancel feeOn-timeN/A
SouthwestCheapest$246Average$477FlexibilityNo cancel feeOn-time63%

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