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$62+ 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 11/1. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — CHI
Oct 11 — Oct 181
Sat 10/11
Sat 10/18
1 adult, Economy
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Cheapflights Tip: The best prices from Ontario to Chicago are usually found in November or September, booked 36 days in advance, depart on a Thursday or Wednesday and return on a Tuesday

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 11, 2025.

Round-trip from

$179
(United Airlines)

One-way from

$62
(Trip.com)

Popular in

March

Cheapest in

November

Average price

$264

Good round-trip deal

$330 or less

Good one-way deal

$196 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. 9% potential increase in price ($37 potential increase over avg. RT price).
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Cheapest flight prices on average. 3% potential price decrease ($11 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 11, 2025.

This United Airlines deal was found by Cheapflights users on 9/11. 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.
Wed 10/17:02 amONT - ORD
Nonstop4h 03mUnited Airlines
Mon 10/67:59 pmORD - ONT
Nonstop4h 31mUnited Airlines
Deal found 9/11$179
This CheapOair deal was found by Cheapflights users on 9/11. 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.
Fri 10/1012:32 pmONT - ORD
1 stop10h 12mFrontier
Sun 10/125:25 amORD - ONT
1 stop28h 24mFrontier
Deal found 9/11$180
This Booking.com deal was found by Cheapflights users on 9/11. 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.
Thu 9/258:59 pmONT - ORD
1 stop25h 00mFrontier
Sat 9/278:25 amORD - ONT
1 stop24h 58mFrontier
Deal found 9/11$181
This Frontier deal was found by Cheapflights users on 9/11. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 10/1212:49 pmONT - ORD
1 stop9h 37mFrontier
Sun 10/199:54 pmORD - ONT
1 stop11h 53mFrontier
Deal found 9/11$182
This CheapOair deal was found by Cheapflights users on 9/11. 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.
Wed 10/156:53 amONT - ORD
1 stop15h 00mFrontier
Mon 10/206:00 amORD - ONT
1 stop12h 28mFrontier
Deal found 9/11$184
This Booking.com deal was found by Cheapflights users on 9/11. 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.
Wed 9/248:00 amONT - ORD
1 stop25h 48mFrontier
Sat 9/278:25 amORD - ONT
1 stop13h 29mFrontier
Deal found 9/11$186
This Booking.com deal was found by Cheapflights users on 9/11. 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.
Sat 10/117:04 amONT - ORD
1 stop14h 49mFrontier
Sat 10/187:05 amORD - ONT
1 stop18h 45mFrontier
Deal found 9/11$188
This CheapOair deal was found by Cheapflights users on 9/11. 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.
Tue 9/308:59 pmONT - ORD
1 stop22h 29mFrontier
Sun 10/129:54 pmORD - ONT
1 stop11h 53mFrontier
Deal found 9/11$189
This Mytrip deal was found by Cheapflights users on 9/11. 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.
Thu 9/258:59 pmONT - ORD
1 stop10h 38mFrontier
Sun 9/288:50 amORD - ONT
1 stop8h 34mFrontier
Deal found 9/11$190
This CheapOair deal was found by Cheapflights users on 9/11. 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.
Tue 9/238:59 pmONT - ORD
1 stop22h 29mFrontier
Wed 10/17:20 amORD - ONT
1 stop26h 03mFrontier
Deal found 9/11$191
This Booking.com deal was found by Cheapflights users on 9/11. 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 10/64:08 pmONT - ORD
1 stop5h 51mFrontier
Thu 10/91:14 pmORD - ONT
1 stop29h 14mFrontier
Deal found 9/11$193
This Kiwi.com deal was found by Cheapflights users on 9/9. 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.
Thu 10/1612:32 pmONT - MDW
1 stop24h 40mFrontier
Sun 10/1910:30 amMDW - ONT
1 stop9h 19mFrontier
Deal found 9/9$194

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 11, 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 - ORD

ONTORD

Ontario

Tue 10/21

7:02 am-1:05 pm

Nonstop4h 03m

Chicago O'Hare Intl

Wed 10/22

7:59 pm-10:30 pm

Nonstop4h 31m

$179

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Sat 10/11

8:34 am-11:20 pm

1 stop12h 46m

Chicago Midway

Sun 10/19

10:30 am-5:49 pm

1 stop9h 19m

$182

OntarioChicago

ONT - ORD

ONTORD

Ontario

Fri 10/17

12:32 pm-12:44 am

1 stop10h 12m

Chicago O'Hare Intl

Sun 10/19

9:54 pm-7:47 am

1 stop11h 53m

$188

OntarioChicago

ONT - ORD

ONTORD

Ontario

Sat 10/18

7:02 am-1:05 pm

Nonstop4h 03m

Chicago O'Hare Intl

Mon 10/20

7:59 pm-10:30 pm

Nonstop4h 31m

$188

OntarioChicago

ONT - ORD

ONTORD

Ontario

Fri 10/24

11:53 am-12:59 am

1 stop11h 06m

Chicago O'Hare Intl

Sun 10/26

9:54 pm-7:47 am

1 stop11h 53m

$192

OntarioChicago

ONT - ORD

ONTORD

Ontario

Thu 10/9

6:54 pm-8:54 pm

1 stop24h 00m

Chicago O'Hare Intl

Mon 10/13

9:54 pm-8:42 pm

1 stop24h 48m

$194

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Sat 10/11

8:34 am-11:20 pm

1 stop12h 46m

Chicago Midway

Fri 10/17

6:24 pm-11:50 pm

1 stop7h 26m

$203

OntarioChicago

ONT - ORD

ONTORD

Ontario

Sat 10/25

6:36 pm-5:13 am

1 stop8h 37m

Chicago O'Hare Intl

Mon 10/27

4:00 pm-6:36 pm

Nonstop4h 36m

$205

OntarioChicago

ONT - ORD

ONTORD

Ontario

Sat 1/10

11:30 am-11:59 pm

1 stop10h 29m

Chicago O'Hare Intl

Sat 1/17

7:45 am-3:12 pm

1 stop9h 27m

$214

OntarioChicago

ONT - ORD

ONTORD

Ontario

Sat 1/10

11:30 am-11:59 pm

1 stop10h 29m

Chicago O'Hare Intl

Mon 1/12

7:45 am-3:12 pm

1 stop9h 27m

$214

Flights are sorted by cheapest round-trip flights first.

Deals found on 9/11

Showing 1-10 of 57 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 August 29, 2025.

The best time to book flights from Ontario to Chicago is 36 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 11, 2025.

Unlike in the evening, when flights are generally more expensive, you can save up to 60% 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 7, 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 11, 2025.

The most flights from ONT to CHI are scheduled on a Monday (2 on average). You will have fewer flight options on Friday, 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 11, 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
4,248 reviews

Food

7.0

Boarding

8.1

Overall

8.0

Entertainment

7.5

Crew

8.6

Comfort

8.0

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
4,248 reviews
Southwest
8.0
Very good
4,248 reviews

Food

7.0

Boarding

8.1

Overall

8.0

Entertainment

7.5

Crew

8.6

Comfort

8.0

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
7,960 reviews
Southwest
8.0
Very good
4,248 reviews

Food

7.0

Boarding

8.1

Overall

8.0

Entertainment

7.5

Crew

8.6

Comfort

8.0

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
8,937 reviews
Southwest
8.0
Very good
4,248 reviews

Food

7.0

Boarding

8.1

Overall

8.0

Entertainment

7.5

Crew

8.6

Comfort

8.0

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
4,248 reviews

Food

7.0

Boarding

8.1

Overall

8.0

Entertainment

7.5

Crew

8.6

Comfort

8.0

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
3,177 reviews
Southwest
8.0
Very good
4,248 reviews

Food

7.0

Boarding

8.1

Overall

8.0

Entertainment

7.5

Crew

8.6

Comfort

8.0

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 6 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?

    United Airlines, Frontier, and Delta 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 $99. Other airlines that can offer you cheap pricing are Frontier, from $108, and United Airlines, from $227. These flights start at 71% 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 Southwest ($92), Frontier ($94), and United Airlines ($98).

  • 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 $752 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 $149.

  • 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 6 airlines flying from Ontario to Chicago

Discover the top 6 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 11, 2025.
AirlineCheapestAverageFlexibilityOn-time
Spirit AirlinesCheapest$99Average$145FlexibilityNo cancel feeOn-time65%
FrontierCheapest$108Average$180FlexibilityNo cancel feeOn-time62%
United AirlinesCheapest$227Average$385FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$237Average$434FlexibilityNo cancel feeOn-time63%
DeltaCheapest$241Average$411FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$246Average$508FlexibilityNo cancel feeOn-time71%

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