HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news
Chicago

$80+ 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 10/3. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — CHI
Aug 15 — Aug 221
Sat 8/15
Sat 8/22
1 adult, Economy
We work with more than 300 partners to bring you better travel deals

Find cheap flights from Ontario to Chicago with Cheapflights

1. Tell us where you want to go

Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”

2. Select your favorite providers

We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.

3. Compare prices and book

Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.
Cheapflights Tip: The best prices from Ontario to Chicago are usually found in September or January, booked 85 days in advance, depart on a Wednesday or Saturday and return on a Wednesday

Cheap 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 16, 2026.

This Frontier deal was found by Cheapflights users on 7/13. 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.
Sat 8/158:17 am
ONT
-
MDW
1 stop7h 09m
Frontier
Fri 8/219:26 pm
MDW
-
ONT
1 stop13h 10m
Frontier
Deal found 7/13$279
This Super.com deal was found by Cheapflights users on 7/14. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/129:36 am
ONT
-
ORD
1 stop12h 57m
Frontier
Sun 8/165:30 pm
ORD
-
ONT
1 stop16h 02m
Frontier
Deal found 7/14$279
This Delta deal was found by Cheapflights users on 7/16. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/1210:59 pm
ONT
-
MDW
2 stops11h 34m
Delta
Mon 11/169:30 am
MDW
-
ONT
2 stops10h 48m
Delta
Deal found 7/16$280
This Frontier deal was found by Cheapflights users on 7/13. 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.
Fri 8/79:36 am
ONT
-
ORD
1 stop12h 57m
Frontier
Wed 8/127:29 am
ORD
-
ONT
1 stop9h 45m
Frontier
Deal found 7/13$280
This Kiwi.com deal was found by Cheapflights users on 7/12. 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 8/2011:15 am
ONT
-
RFD
1 stop7h 30m
Multiple Airlines
Sun 8/233:59 pm
RFD
-
ONT
2 stops33h 51m
Multiple Airlines
Deal found 7/12$281
This Kiwi.com deal was found by Cheapflights users on 7/15. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/56:00 am
ONT
-
ORD
1 stop12h 52m
Frontier
Mon 8/109:57 pm
ORD
-
ONT
1 stop14h 07m
Frontier
Deal found 7/15$281
This CheapOair deal was found by Cheapflights users on 7/15. 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.
Tue 8/1810:59 am
ONT
-
ORD
1 stop27h 00m
Frontier
Sun 8/235:46 pm
ORD
-
ONT
1 stop15h 46m
Frontier
Deal found 7/15$283
This Frontier deal was found by Cheapflights users on 7/14. 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.
Thu 8/138:17 am
ONT
-
MDW
1 stop10h 15m
Frontier
Sun 8/169:27 pm
MDW
-
ONT
1 stop13h 14m
Frontier
Deal found 7/14$284
This Expedia deal was found by Cheapflights users on 7/14. 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/69:36 am
ONT
-
ORD
1 stop12h 57m
Frontier
Tue 8/119:57 pm
ORD
-
ONT
1 stop27h 53m
Frontier
Deal found 7/14$284
This Frontier deal was found by Cheapflights users on 7/15. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/179:36 am
ONT
-
ORD
1 stop12h 57m
Frontier
Mon 8/242:41 pm
ORD
-
ONT
1 stop11h 09m
Frontier
Deal found 7/15$285
This Frontier deal was found by Cheapflights users on 7/16. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/208:17 am
ONT
-
MDW
1 stop10h 14m
Frontier
Mon 8/249:26 pm
MDW
-
ONT
1 stop13h 10m
Frontier
Deal found 7/16$286
This Booking.com deal was found by Cheapflights users on 7/15. 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.
Thu 9/33:40 pm
ONT
-
ORD
1 stop25h 22m
Frontier
Sun 9/68:11 pm
ORD
-
ONT
1 stop13h 52m
Frontier
Deal found 7/15$286

Find 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 16, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$279
(Frontier)

One-way from

$80
(Trip.com)

Popular in

December

Cheapest in

September

Average price

$447

Good round-trip deal

$372 or less

Good one-way deal

$198 or less
Provider with most accurate pricing for Ontario-Chicago (CHI) flight deals.
Search Deals
Provider most trusted by Cheapflights users for Ontario-Chicago (CHI) flights.
Search Deals
From Ontario to Chicago (CHI)
Search Deals
One-way flight from Ontario to Chicago (CHI)
Search Deals
Highest demand for flights based on searches. 4% potential increase in price ($22 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($11 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in July 2026
Search Deals
Price to beat on a round-trip flight from Ontario to Chicago (CHI).
Search Deals
Price to beat on a one-way flight from Ontario to Chicago (CHI).
Search Deals

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 16, 2026.
Use the filters below to find and compare flights from Ontario to Chicago that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

OntarioChicago

ONT - RFD

ONTRFD

Ontario

Thu 8/20

11:15 am-8:45 pm

1 stop7h 30m

Chicago Greater Rockford

Sun 8/23

3:59 pm-11:50 pm

2 stops33h 51m

$281

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Mon 10/12

11:15 pm-12:48 pm

2 stops11h 33m

Chicago Midway

Thu 10/15

1:28 pm-10:43 pm

2 stops11h 15m

$309

OntarioChicago

ONT - ORD

ONTORD

Ontario

Mon 9/21

10:00 pm-12:59 pm

2 stops12h 59m

Chicago O'Hare Intl

Wed 9/23

5:10 pm-11:47 pm

2 stops8h 37m

$309

OntarioChicago

ONT - ORD

ONTORD

Ontario

Tue 9/8

7:00 am-1:10 pm

Nonstop4h 10m

Chicago O'Hare Intl

Thu 9/10

8:30 pm-10:59 pm

Nonstop4h 29m

$321
Quickest round-trip

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Tue 9/1

11:55 pm-5:45 am

Nonstop3h 50m

Chicago Midway

Fri 9/4

2:00 pm-4:10 pm

Nonstop4h 10m

$343

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Mon 10/5

11:55 pm-5:40 am

Nonstop3h 45m

Chicago Midway

Fri 10/9

11:55 am-2:10 pm

Nonstop4h 15m

$343

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Mon 9/21

8:00 pm-5:55 am

1 stop7h 55m

Chicago Midway

Wed 9/23

10:30 am-4:05 pm

2 stops7h 35m

$348

OntarioChicago

ONT - ORD

ONTORD

Ontario

Wed 9/2

1:18 pm-10:46 pm

1 stop7h 28m

Chicago O'Hare Intl

Thu 10/1

8:20 pm-10:49 pm

Nonstop4h 29m

$349

OntarioChicago

ONT - ORD

ONTORD

Ontario

Sun 8/9

6:10 am-12:25 pm

Nonstop4h 15m

Chicago O'Hare Intl

Wed 8/12

5:55 am-12:50 pm

1 stop8h 55m

$353

OntarioChicago

ONT - ORD

ONTORD

Ontario

Wed 8/19

1:18 pm-10:00 pm

1 stop6h 42m

Chicago O'Hare Intl

Sat 8/29

8:06 pm-10:35 pm

Nonstop4h 29m

$359

Flights are sorted by cheapest round-trip flights first.

Deals found on 7/14

Showing 1-10 of 57 resultsSorted by cheapest first
1
2
3
...
6

Compare providers for flights from Ontario to Chicago

Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.
Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from Ontario to Chicago in July.
ProviderPrice AccuracyTrust Score*
ExpediaPrice Accuracy1 starTrust Score*3 stars
FlightHubPrice Accuracy3 starsTrust Score*3 stars
MytripPrice Accuracy2 starsTrust Score*3 stars
CheapfaremartPrice Accuracy-Trust Score*1 star

*The Trust Score is based on feedback from users after their booking experience. It measures overall satisfaction, helping us identify issues like hidden fees, problems during the ticketing process, and the quality of customer service. This score is our best indicator of the provider's quality and reliability.

  • Most accurate provider: When it comes to deals on Ontario-Chicago flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on Ontario-Chicago flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from Ontario-Chicago flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on Ontario-Chicago flights, Cheapflights users trust FlightHub the most. FlightHub has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for Ontario-Chicago flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.

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

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

Currently, April is the cheapest month in which you can book a flight from Ontario to Chicago (average of $108). Flying from Ontario to Chicago in March is currently the most expensive (average of $186). 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 16, 2026.

When flying from Ontario to Chicago, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.

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 July 16, 2026.

The most flights from ONT to CHI are scheduled on a Monday (4 on average). You will have fewer flight options on Friday, which is when the least amount of flights are scheduled (3 on average).

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

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

The best time to book flights from Ontario to Chicago is 75 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.

The best insider tips for Ontario to Chicago flights

AI-powered summary based on content written by travel experts. AI can make mistakes.
Cheapflights partnered with top experts to bring you the best recommendations for your Ontario to Chicago trip
Our travel experts
Ramsey Qubein

Ramsey Qubein

Expert on MDW

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 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

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 16, 2026.
See what other customers who have flown with Southwest,Delta, andUnited 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

Comfort

8.0

Crew

8.6

Food

7.0

Overall

8.0

Boarding

8.1

Reviews

1 / 20
6.0
Good

Reza,Jun 2026

TPA - MDW

The seats were super cramped and couldn’t move without hitting other passengers
Southwest
8.0
Very good
4,242 reviews
Southwest
8.0
Very good
4,242 reviews

Entertainment

7.5

Comfort

8.0

Crew

8.6

Food

7.0

Overall

8.0

Boarding

8.1

Reviews

1 / 20
6.0
Good

Reza,Jun 2026

TPA - MDW

The seats were super cramped and couldn’t move without hitting other passengers
Delta
7.8
Good
8,472 reviews
Southwest
8.0
Very good
4,242 reviews

Entertainment

7.5

Comfort

8.0

Crew

8.6

Food

7.0

Overall

8.0

Boarding

8.1

Reviews

1 / 20
6.0
Good

Reza,Jun 2026

TPA - MDW

The seats were super cramped and couldn’t move without hitting other passengers
United Airlines
7.4
Good
9,993 reviews
Southwest
8.0
Very good
4,242 reviews

Entertainment

7.5

Comfort

8.0

Crew

8.6

Food

7.0

Overall

8.0

Boarding

8.1

Reviews

1 / 20
6.0
Good

Reza,Jun 2026

TPA - MDW

The seats were super cramped and couldn’t move without hitting other passengers
Frontier
5.6
Fair
2,796 reviews
Southwest
8.0
Very good
4,242 reviews

Entertainment

7.5

Comfort

8.0

Crew

8.6

Food

7.0

Overall

8.0

Boarding

8.1

Reviews

1 / 20
6.0
Good

Reza,Jun 2026

TPA - MDW

The seats were super cramped and couldn’t move without hitting other passengers

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 3 outbound flights 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?

    Delta, United Airlines, and Southwest can get you from Ontario to Chicago in just under 3h 50m. Your travel time can differ by up to 7h 43m. The distance from Ontario to Chicago is about 1701 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 $131. Other airlines that can offer you cheap pricing are Southwest, from $258, and Delta, from $260. 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 Frontier ($85), American Airlines ($118), and Delta ($118).

  • 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 $757 for a flight from Ontario to Chicago. The cheapest flight overall is $169 while the most popular route, (Ontario - Chicago O'Hare Intl) is currently priced at $227.

  • 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, April is the cheapest month in which you can book a flight from Ontario to Chicago (average of $108). Flying from Ontario to Chicago in March is currently the most expensive (average of $186). 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
Benton Harbor
Lansing
Merrillville
Valparaiso
Hammond
Saint Joseph
Porter

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for Ontario to Chicago

See prices for flight routes from nearby airports that may be better suited for you.
Los Angeles to O'Hare Intl flights
San Francisco to O'Hare Intl flights
Ontario to O'Hare Intl flights
Santa Ana to O'Hare Intl flights
Los Angeles to Midway flights
San Francisco to Midway flights
San Jose to O'Hare Intl flights
San Diego to O'Hare Intl flights
Burbank to O'Hare Intl flights
Sacramento to O'Hare Intl flights
Oakland to O'Hare Intl flights
Las Vegas to O'Hare Intl flights
Los Angeles to St. Louis flights
Las Vegas to Midway flights
Ontario to Midway flights
Santa Ana to Midway flights
Fresno to O'Hare Intl flights
San Jose to Midway flights
San Diego to Midway flights
Long Beach to O'Hare Intl flights
San Francisco to St. Louis flights
Oakland to Midway flights
Ontario to St. Louis flights
San Diego to St. Louis flights
Sacramento to Midway flights
Reno to O'Hare Intl flights
Burbank to St. Louis flights
Burbank to Midway flights
Las Vegas to St. Louis flights
Los Angeles to Rockford flights
Santa Barbara to O'Hare Intl flights
San Francisco to Rockford flights
Fresno to Midway flights
Palm Springs to O'Hare Intl flights
Santa Ana to St. Louis flights
Oakland to St. Louis flights
Sacramento to St. Louis flights
San Jose to St. Louis flights
Long Beach to Midway flights
Los Angeles to Moline flights
Reno to Midway flights
Monterey to O'Hare Intl flights
Long Beach to St. Louis flights
Ontario to Moline flights
Palm Springs to St. Louis flights
Burbank to Moline flights
Palm Springs to Midway flights
Medford to O'Hare Intl flights
Santa Rosa to O'Hare Intl flights

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 July 16, 2026.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$131Average$263FlexibilityNo cancel feeOn-time62%
SouthwestCheapest$258Average$431FlexibilityNo cancel feeOn-time63%
DeltaCheapest$260Average$446FlexibilityNo cancel feeOn-timeN/A
United AirlinesCheapest$264Average$451FlexibilityNo cancel feeOn-time69%
American AirlinesCheapest$276Average$516FlexibilityNo cancel feeOn-time71%

100% Free

Cheapflights is completely free to use, so you can start saving the moment you arrive.

Book with Flexibility

Our users can plan ahead with confidence and find flights with no change fees

Travel Smart

Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.