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$79+ Cheap flights from Ontario (ONT) to Chicago (CHI)

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 10/6. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — CHI
Oct 17 — Oct 241
Fri 10/17
Fri 10/24
1 adult, Economy
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Cheapflights Tip: The best prices from Ontario to Chicago are usually found in November or October, booked 49 days in advance, depart on a Wednesday or Thursday and return on a Thursday

Cheap flight deals from Ontario to Chicago

Discover tips and strategies to find the most affordable flight options for your journey from Ontario (ONT) to Chicago (CHI). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated September 17, 2025.

Round-trip from

$173
(Trip.com)

One-way from

$79
(Cheapflightsfares)

Popular in

March

Cheapest in

November

Average price

$287

Good round-trip deal

$343 or less

Good one-way deal

$198 or less
From Ontario to Chicago (CHI)
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One-way flight from Ontario to Chicago (CHI)
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Highest demand for flights based on searches. 8% potential increase in price ($32 potential increase over avg. RT price).
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Cheapest flight prices on average. 2% potential price decrease ($10 potential savings vs. average RT price).
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Average for round-trip flights in September 2025
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Price to beat on a round-trip flight from Ontario to Chicago (CHI).
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Price to beat on a one-way flight from Ontario to Chicago (CHI).
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Find flight deals from Ontario to Chicago

Cheapest flights from Ontario to Chicago
Explore the most affordable flight options available from Ontario to Chicago. Find the lowest fares from popular airlines and budget airlines, with prices last updated on September 17, 2025.

This Trip.com deal was found by Cheapflights users on 9/17. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/1311:59 amONT - MDW
1 stop6h 45mFrontier
Sun 11/166:30 amMDW - ONT
1 stop14h 19mFrontier
Deal found 9/17$173
This Booking.com deal was found by Cheapflights users on 9/16. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/2912:13 pmONT - MDW
1 stop6h 39mFrontier
Thu 10/26:30 amMDW - ONT
1 stop14h 05mFrontier
Deal found 9/16$174
This Booking.com deal was found by Cheapflights users on 9/16. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/268:59 pmONT - ORD
1 stop22h 29mFrontier
Tue 9/307:20 amORD - ONT
1 stop14h 34mFrontier
Deal found 9/16$174
This Trip.com deal was found by Cheapflights users on 9/16. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/2312:32 pmONT - MDW
1 stop24h 40mFrontier
Thu 10/309:43 pmMDW - ONT
1 stop11h 46mFrontier
Deal found 9/16$178
This CheapOair deal was found by Cheapflights users on 9/15. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/188:34 amONT - ORD
1 stop13h 25mFrontier
Sat 10/2512:05 pmORD - ONT
1 stop21h 44mFrontier
Deal found 9/15$178
This Trip.com deal was found by Cheapflights users on 9/17. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/58:45 amONT - MDW
1 stop24h 45mFrontier
Fri 11/78:55 amMDW - ONT
1 stop11h 33mFrontier
Deal found 9/17$179
This Kiwi.com deal was found by Cheapflights users on 9/16. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/2411:53 amONT - ORD
1 stop11h 06mFrontier
Fri 10/311:36 pmORD - ONT
1 stop7h 13mFrontier
Deal found 9/16$179
This Cheapflightsfares deal was found by Cheapflights users on 9/16. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/312:13 pmONT - MDW
1 stop6h 39mFrontier
Sun 10/510:18 amMDW - ONT
1 stop7h 06mFrontier
Deal found 9/16$185
This Kiwi.com deal was found by Cheapflights users on 9/16. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/278:59 pmONT - ORD
1 stop10h 38mFrontier
Tue 9/307:20 amORD - ONT
1 stop14h 34mFrontier
Deal found 9/16$185
This CheapOair deal was found by Cheapflights users on 9/15. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/64:08 pmONT - ORD
1 stop5h 51mFrontier
Tue 10/77:15 amORD - ONT
1 stop18h 35mFrontier
Deal found 9/15$186
This Trip.com deal was found by Cheapflights users on 9/16. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/206:53 amONT - MDW
1 stop15h 31mFrontier
Thu 10/2310:30 amMDW - ONT
1 stop9h 24mFrontier
Deal found 9/16$187
This Booking.com deal was found by Cheapflights users on 9/15. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/312:13 pmONT - MDW
1 stop6h 39mFrontier
Sun 10/1210:30 amMDW - ONT
1 stop9h 19mFrontier
Deal found 9/15$188

Cheapflights Fare Finder

 
Customize your flight search to find flights from Ontario to Chicago 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 September 17, 2025.
Use the filters below to find and compare flights from Ontario to Chicago that are best for you.

Fly from

Ontario

Fly to

Chicago

Route

Depart

Return

Price

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Sat 10/11

8:34 am-11:20 pm

1 stop12h 46m

Chicago Midway

Mon 10/13

9:00 am-4:28 pm

1 stop9h 28m

$223

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Thu 10/23

10:30 am-11:20 pm

2 stops10h 50m

Chicago Midway

Mon 10/27

9:00 am-4:28 pm

1 stop9h 28m

$230

OntarioChicago

ONT - RFD

ONTRFD

Ontario

Thu 9/25

9:16 am-7:47 pm

1 stop8h 31m

Chicago Greater Rockford

Sun 9/28

8:37 pm-7:17 am

1 stop12h 40m

$270

OntarioChicago

ONT - ORD

ONTORD

Ontario

Wed 10/29

11:48 am-11:50 pm

1 stop10h 02m

Chicago O'Hare Intl

Sat 11/1

2:20 pm-10:41 pm

1 stop10h 21m

$277

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Wed 10/29

11:36 am-10:14 pm

1 stop8h 38m

Chicago Midway

Sat 11/1

9:20 am-9:20 pm

2 stops14h 00m

$364

OntarioChicago

ONT - ORD

ONTORD

Ontario

Tue 9/30

10:00 pm-5:47 pm

2 stops17h 47m

Chicago O'Hare Intl

Wed 10/15

7:37 am-5:10 pm

1 stop11h 33m

$369

OntarioChicago

ONT - ORD

ONTORD

Ontario

Tue 10/14

7:02 am-1:05 pm

Nonstop4h 03m

Chicago O'Hare Intl

Thu 10/16

7:59 pm-10:30 pm

Nonstop4h 31m

$377

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Tue 10/21

4:25 pm-12:05 am

1 stop5h 40m

Chicago Midway

Thu 10/23

1:20 pm-3:35 pm

Nonstop4h 15m

$387

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Tue 10/14

5:15 am-1:35 pm

1 stop6h 20m

Chicago Midway

Tue 10/21

11:15 am-1:30 pm

Nonstop4h 15m

$387

OntarioChicago

ONT - ORD

ONTORD

Ontario

Tue 10/21

1:15 pm-9:30 pm

1 stop6h 15m

Chicago O'Hare Intl

Sat 10/25

3:35 pm-6:06 pm

Nonstop4h 31m

$387

Flights are sorted by cheapest round-trip flights first.

Deals found on 9/16

Showing 1-10 of 48 results
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The best insider tips for Ontario to Chicago flights

Snippets provided in this section are AI-generated based on a summarization of Cheapflights-commissioned articles. The articles are presented as-is, for general informational purposes only, and may not be up-to-date. The opinions contained in the articles are original to the author and reflect their authentic experience, which may vary significantly from the experience of others.
Cheapflights partnered with top experts to bring you the best recommendations for your Ontario to Chicago trip
Airports
ONT

For business travelers, ONT offers a smooth security process, often quicker than LAX, making it ideal for weekday commutes.

Read more about ONTby Bill Fink
MDW

Use the Orange Line train for a quick, budget-friendly trip from MDW to downtown Chicago in under 30 minutes.

Read more about MDWby Ramsey Qubein
Our travel experts
Ramsey Qubein

Ramsey Qubein

Expert on MDW

Ramsey Qubein

Ramsey Qubein

An avid traveler and aviation expert who has visited 173 countries, all 50 states and seven continents, Ramsey Qubein flies nearly 400,000 miles a year. As a North Carolina-based freelance journalist for publications including Conde Nast Traveler, Forbes, USA Today and Bloomberg among others, he explores the latest trends in aviation, hospitality, cruises and business.

Read more
Bill Fink

Bill Fink

Expert on ONT

Bill Fink

Bill Fink

Bill is an award-winning travel writer with extensive credits covering airlines and the aviation industry for publications including AARP, AFAR, The Points Guy and Yahoo. Based in Portland, Oregon, Bill has traveled to more than 75 countries - and been late for his flight in most of them. He once achieved top-level frequent flier status for all of American, Delta and United Airlines during a single year.

Read more

Best time to book a flight from Ontario to Chicago

Have a flexible travel schedule? Discover the best time to fly to Chicago from Ontario 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 Ontario to Chicago

How far ahead should I book a flight from Ontario to Chicago?

Use this chart to determine the optimal time to book a round-trip flight from Ontario to Chicago. Price data was last updated on September 12, 2025.

The best time to book flights from Ontario to Chicago is 49 days before your desired departure date. The cost of your flight will likely increase significantly if you book two weeks in advance of your flight.

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

Currently, August is the cheapest month in which you can book a flight from Ontario to Chicago (average of $245). Flying from Ontario to Chicago in March is currently the most expensive (average of $321). 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 ONT to CHI?

Find hourly flight availability from Ontario to Chicago. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated September 17, 2025.

Unlike in the evening, when flights are generally more expensive, you can save up to 55% on flights from Ontario to Chicago by exploring options for tickets in the afternoon.

What is the cheapest day to fly from Ontario to Chicago?

Use this chart to determine the cheapest time to fly round-trip from Ontario to Chicago. Price data was last updated on September 14, 2025.

Travelers seeking maximum savings on their Ontario to Chicago flight should consider departing on Wednesday evenings when fares are most often at their lowest. Tuesday at noon flights should be avoided if possible as fares are typically the most expensive at this time.

Weekly flight availability from Ontario to Chicago

Explore weekly flight availability from Ontario to Chicago. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated September 17, 2025.

The most flights from ONT to CHI are scheduled on a Monday (2 on average). You will have fewer flight options on Thursday, which is when the least amount of flights are scheduled (1 on average).

Reviews of airlines servicing Chicago

Get insights into the airlines that provide service to Chicago. 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 Chicago. Reviews last updated September 17, 2025.
See what other customers who have flown with Southwest, Delta, and United Airlines from Ontario to Chicago have to say. You can also see how each airline compares in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.0
Very good
4,242 reviews

Entertainment

7.5

Food

7.0

Overall

8.0

Comfort

8.0

Crew

8.6

Boarding

8.1

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Southwest
8.0
Very good
4,242 reviews
Southwest
8.0
Very good
4,242 reviews

Entertainment

7.5

Food

7.0

Overall

8.0

Comfort

8.0

Crew

8.6

Boarding

8.1

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Delta
8.0
Very good
7,961 reviews
Southwest
8.0
Very good
4,242 reviews

Entertainment

7.5

Food

7.0

Overall

8.0

Comfort

8.0

Crew

8.6

Boarding

8.1

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
United Airlines
7.4
Good
8,926 reviews
Southwest
8.0
Very good
4,242 reviews

Entertainment

7.5

Food

7.0

Overall

8.0

Comfort

8.0

Crew

8.6

Boarding

8.1

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
American Airlines
7.2
Good
10,000 reviews
Southwest
8.0
Very good
4,242 reviews

Entertainment

7.5

Food

7.0

Overall

8.0

Comfort

8.0

Crew

8.6

Boarding

8.1

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Frontier
5.8
Fair
3,173 reviews
Southwest
8.0
Very good
4,242 reviews

Entertainment

7.5

Food

7.0

Overall

8.0

Comfort

8.0

Crew

8.6

Boarding

8.1

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.

Related info for your journey

Find useful and relevant information for your journey from Ontario to Chicago. 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 from for flights from Ontario to Chicago?

    Ontario (ONT) is the airport you will fly out of if you book a flight from Ontario to Chicago. You should not have trouble finding flights to Chicago from Ontario; the airport handles an average of 1 outbound flight to Chicago per day. You should also have plenty of airline options to choose from since 5 airlines have flights from the Ontario airport to Chicago. It is only a 3.1 mi journey to Ontario (ONT) from Ontario’s city center.

  • How long is the flight from Ontario to Chicago?

    Frontier, Delta, and United Airlines can get you from Ontario to Chicago in just under 4h 03m. Your travel time can differ by up to 8h 43m. The distance from Ontario to Chicago is about 1695 mi. When browsing for deals, the options you’ll see will be for both nonstop flights and flights with stops.

  • What are the cheapest airlines flying from Ontario to Chicago round-trip?

    Cheapflights users have booked flights from Ontario to Chicago round-trip from $108. Other airlines that can offer you cheap pricing are United Airlines, from $227, and Delta, from $236. These flights start at 69% lower than the current average price 3 months from now.

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

    The cheapest airlines for a one-way flight from Ontario to Chicago are Delta ($153), Southwest ($179), and Alaska Airlines ($179).

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

    Most travelers choose Ontario - Chicago O'Hare Intl, Ontario - Chicago Midway or Ontario - Chicago Greater Rockford when deciding on the best route from Ontario to Chicago.

  • What are the cheapest flights from Ontario to Chicago?

    On average you can expect to pay $805 for a flight from Ontario to Chicago. The cheapest flight overall is $156 while the most popular route, (Ontario - Chicago O'Hare Intl) is currently priced at $148.

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

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

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

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

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

    Yes. Cheapflights offers flight deals from Ontario to Chicago 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 Ontario to Chicago?

    Currently, August is the cheapest month in which you can book a flight from Ontario to Chicago (average of $245). Flying from Ontario to Chicago in March is currently the most expensive (average of $321). 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

Traveling to a place near Chicago?

Book flights to Chicago if you plan to visit one of these locations
Merrillville
Lansing
Hammond
Benton Harbor
Porter
Chesterton

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Alternative routes for Ontario to Chicago

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

Discover the top 5 airlines that operate flights from Ontario to Chicago. 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 September 17, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$108Average$184FlexibilityNo cancel feeOn-time62%
United AirlinesCheapest$227Average$390FlexibilityNo cancel feeOn-time69%
DeltaCheapest$236Average$409FlexibilityNo cancel feeOn-timeN/A
SouthwestCheapest$237Average$437FlexibilityNo cancel feeOn-time63%
American AirlinesCheapest$246Average$508FlexibilityNo cancel feeOn-time71%

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