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$117+ 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 9/3. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — CHI
Aug 5 — Aug 121
Tue 8/5
1 adult, Economy
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Cheapflights Tip: The best prices from Ontario to Chicago are usually found in November or October, booked 79 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 July 31, 2025.

Round-trip from

$251
(Booking.com)

One-way from

$117
(Cheapflightsfares)

Popular in

March

Cheapest in

November

Average price

$370

Good round-trip deal

$298 or less

Good one-way deal

$193 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. 10% 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 July 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 July 31, 2025.

This Booking.com deal was found by Cheapflights users on 7/31. 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 8/412:59 amONT - ORD
1 stop21h 33mFrontier
Fri 8/159:56 pmORD - ONT
1 stop25h 56mFrontier
Deal found 7/31$251
This Booking.com deal was found by Cheapflights users on 7/30. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 9/148:59 pmONT - MDW
1 stop16h 54mFrontier
Sun 9/2110:18 amMDW - ONT
1 stop7h 06mFrontier
Deal found 7/30$257
This American Airlines deal was found by Cheapflights users on 7/29. 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 8/266:17 amONT - ORD
1 stop10h 00mAmerican Airlines
Sat 8/308:00 amORD - ONT
1 stop10h 24mAmerican Airlines
Deal found 7/29$274
This Delta deal was found by Cheapflights users on 7/30. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/237:05 amONT - ORD
1 stop7h 23mDelta
Sat 8/306:24 pmORD - ONT
1 stop6h 16mDelta
Deal found 7/30$305
This Alaska Airlines deal was found by Cheapflights users on 7/31. 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.
Tue 9/911:39 amONT - ORD
1 stop8h 28mAlaska Airlines
Wed 9/108:00 amORD - ONT
1 stop8h 12mAlaska Airlines
Deal found 7/31$306
This Delta deal was found by Cheapflights users on 7/31. 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 9/311:45 amONT - MDW
1 stop7h 41mDelta
Tue 9/1612:43 pmMDW - ONT
1 stop8h 32mDelta
Deal found 7/31$307
This Southwest deal was found by Cheapflights users on 7/29. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/188:05 amONT - MDW
Nonstop3h 50mSouthwest
Tue 10/2111:15 amMDW - ONT
Nonstop4h 15mSouthwest
Deal found 7/29$317
This United Airlines deal was found by Cheapflights users on 7/31. 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 9/137:00 amONT - ORD
Nonstop4h 03mUnited Airlines
Tue 9/163:58 pmORD - ONT
1 stop7h 27mUnited Airlines
Deal found 7/31$327

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 July 31, 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

Mon 8/4

12:59 am-12:32 am

1 stop21h 33m

Chicago O'Hare Intl

Fri 8/15

9:56 pm-9:52 pm

1 stop25h 56m

$251

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Sun 9/14

8:59 pm-3:53 pm

1 stop16h 54m

Chicago Midway

Sun 9/21

10:18 am-3:24 pm

1 stop7h 06m

$257

OntarioChicago

ONT - ORD

ONTORD

Ontario

Tue 8/26

6:17 am-6:17 pm

1 stop10h 00m

Chicago O'Hare Intl

Sat 8/30

8:00 am-4:24 pm

1 stop10h 24m

$274

OntarioChicago

ONT - ORD

ONTORD

Ontario

Sat 8/23

7:05 am-4:28 pm

1 stop7h 23m

Chicago O'Hare Intl

Sat 8/30

6:24 pm-10:40 pm

1 stop6h 16m

$305

OntarioChicago

ONT - ORD

ONTORD

Ontario

Tue 9/9

11:39 am-10:07 pm

1 stop8h 28m

Chicago O'Hare Intl

Wed 9/10

8:00 am-2:12 pm

1 stop8h 12m

$306

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Wed 9/3

11:45 am-9:26 pm

1 stop7h 41m

Chicago Midway

Tue 9/16

12:43 pm-7:15 pm

1 stop8h 32m

$307

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Sat 10/18

8:05 am-1:55 pm

Nonstop3h 50m

Chicago Midway

Tue 10/21

11:15 am-1:30 pm

Nonstop4h 15m

$317

OntarioChicago

ONT - ORD

ONTORD

Ontario

Sat 9/13

7:00 am-1:03 pm

Nonstop4h 03m

Chicago O'Hare Intl

Tue 9/16

3:58 pm-9:25 pm

1 stop7h 27m

$327

OntarioChicago

ONT - ORD

ONTORD

Ontario

Tue 8/26

2:10 pm-11:40 pm

1 stop7h 30m

Chicago O'Hare Intl

Tue 9/2

6:15 am-10:10 am

1 stop5h 55m

$337

OntarioChicago

ONT - ORD

ONTORD

Ontario

Wed 9/3

12:59 am-9:37 am

1 stop6h 38m

$117

Flights are sorted by cheapest round-trip flights first.

Deals found on 7/29

Showing 1-10 of 20 results
1
2

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 July 25, 2025.

The best time to book flights from Ontario to Chicago is 79 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 July 31, 2025.

Unlike at noon, when flights are generally more expensive, you can save up to 54% on flights from Ontario to Chicago by exploring options for tickets in the evening.

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 July 27, 2025.

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

What’s the top layover airport for flights from Ontario to Chicago?

Share of 1-stop round-trip flights from Ontario to Chicago chosen by Cheapflights users in the past 12 months, using the same layover each way.

Denver (DEN) – chosen by Cheapflights users on 40% of 1-stop itineraries from Ontario to Chicago on Cheapflights.

What’s the cheapest layover airport for flights from Ontario to Chicago?

Average round-trip fare for 1-stop flights from Ontario to Chicago, chosen by Cheapflights users in the past 12 months, with the same layover each way.

Las Vegas (LAS) is the most affordable 1-stop option, with an average round-trip price of $150.

What’s the fastest layover option from Ontario to Chicago?

Shortest average travel time for 1-stop one-way flights from Ontario to Chicago, based on itineraries clicked by Cheapflights users over the past 12 months, grouped by layover airport.

Flights via Seattle (SEA) have the shortest average one-way travel time for 1-stop routes: 7h 54m.

Which airport typically offers the quickest layover for flights from Ontario to Chicago?

Average layover duration for 1-stop one-way flights from Ontario to Chicago, chosen by Cheapflights users in the last 12 months, grouped by stopover airport.

Flights via Seattle (SEA) offer the fastest connection on this route, with an average layover time of 0h 54m.

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 July 31, 2025.
See what other customers who have flown with Alaska Airlines, Southwest, and Delta 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.
Alaska Airlines
8.0
Very good
10,000 reviews

Food

7.1

Overall

8.0

Boarding

8.1

Crew

8.5

Entertainment

7.1

Comfort

7.8

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

Food

7.1

Overall

8.0

Boarding

8.1

Crew

8.5

Entertainment

7.1

Comfort

7.8

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
4,246 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Food

7.1

Overall

8.0

Boarding

8.1

Crew

8.5

Entertainment

7.1

Comfort

7.8

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
7,981 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Food

7.1

Overall

8.0

Boarding

8.1

Crew

8.5

Entertainment

7.1

Comfort

7.8

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
2,611 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Food

7.1

Overall

8.0

Boarding

8.1

Crew

8.5

Entertainment

7.1

Comfort

7.8

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
8,900 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Food

7.1

Overall

8.0

Boarding

8.1

Crew

8.5

Entertainment

7.1

Comfort

7.8

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 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.

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

    Cheapflights users have booked flights from Ontario to Chicago round-trip from $251. Other airlines that can offer you cheap pricing are American Airlines, from $274, and Delta, from $305. These flights start at 26% 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 Frontier ($117), American Airlines ($147), and Hawaiian Airlines ($153).

  • 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 $920 for a flight from Ontario to Chicago. The cheapest flight overall is $102 while the most popular route, (Ontario - Chicago O'Hare Intl) is currently priced at $240.

  • 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
Valparaiso
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 July 31, 2025.
AirlineCheapestAverageFlexibilityOn-time
Spirit AirlinesCheapest$99Average$172FlexibilityNo cancel feeOn-time65%
FrontierCheapest$108Average$174FlexibilityNo cancel feeOn-time62%
United AirlinesCheapest$227Average$377FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$237Average$443FlexibilityNo cancel feeOn-time63%
DeltaCheapest$241Average$406FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$246Average$503FlexibilityNo cancel feeOn-time71%

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