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$99+ 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 5/24. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — CHI
May 6 — May 131
Tue 5/6
Tue 5/13
1 adult, Economy
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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

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3. Compare prices and book

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Cheapflights Tip: The best prices from Ontario to Chicago are usually found in November or September, booked 79 days in advance, depart on a Tuesday or Wednesday and return on a Saturday

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 May 1, 2025.

Most accurate provider

Flightnetwork
3 stars

Most trusted provider

Flightnetwork
3 stars

Round-trip from

$235
(Trip.com)

One-way from

$99
(Gotogate)

Popular in

March

Cheapest in

November

Average price

$350

Good round-trip deal

$317 or less

Good one-way deal

$158 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.
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From Ontario to Chicago (CHI)
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One-way flight from Ontario to Chicago (CHI)
Search Deals
Highest demand for flights based on searches. 9% potential increase in price ($33 potential increase over avg. RT price).
Search Deals
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 May 2025
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).
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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 May 1, 2025.

This FlightHub deal was found by Cheapflights users on 4/28. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/112:59 amONT - ORD
1 stop20h 42mFrontier
Sat 5/246:00 amORD - ONT
1 stop29h 15mFrontier
Deal found 4/28$232
This Trip.com deal was found by Cheapflights users on 4/29. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/1510:15 pmONT - MDW
1 stop14h 33mFrontier
Mon 5/198:03 pmMDW - ONT
1 stop5h 56mFrontier
Deal found 4/29$235
This Southwest deal was found by Cheapflights users on 4/29. 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.
Fri 5/304:55 pmONT - MDW
1 stop6h 10mSouthwest
Fri 6/612:35 pmMDW - ONT
Nonstop4h 10mSouthwest
Deal found 4/29$237
This United Airlines deal was found by Cheapflights users on 4/29. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 6/67:00 amONT - ORD
Nonstop4h 03mUnited Airlines
Tue 6/1012:45 pmORD - ONT
1 stop6h 40mUnited Airlines
Deal found 4/29$237
This Southwest deal was found by Cheapflights users on 4/29. 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.
Thu 7/173:20 pmONT - ORD
1 stop6h 20mSouthwest
Mon 7/215:25 pmORD - ONT
1 stop5h 45mSouthwest
Deal found 4/29$242
This Alaska Airlines deal was found by Cheapflights users on 4/29. 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 Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/217:10 amONT - ORD
1 stop19h 50mAlaska Airlines
Tue 8/266:20 amORD - ONT
1 stop9h 49mAlaska Airlines
Deal found 4/29$246
This American Airlines deal was found by Cheapflights users on 4/30. 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.
Sat 6/144:50 pmONT - ORD
1 stop5h 42mAmerican Airlines
Sat 6/214:45 pmORD - ONT
1 stop6h 53mAmerican Airlines
Deal found 4/30$249
This Delta deal was found by Cheapflights users on 4/29. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/510:59 pmONT - MDW
1 stop8h 52mDelta
Tue 9/91:05 pmMDW - ONT
1 stop8h 37mDelta
Deal found 4/29$257
This Delta deal was found by Cheapflights users on 4/29. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 6/111:15 pmONT - ORD
1 stop6h 54mDelta
Sat 6/287:40 amORD - ONT
1 stop6h 37mDelta
Deal found 4/29$257
This Hawaiian Airlines deal was found by Cheapflights users on 4/28. 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 Hawaiian Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/2811:51 amONT - ORD
1 stop8h 32mHawaiian Airlines
Wed 6/48:00 amORD - ONT
1 stop9h 50mHawaiian Airlines
Deal found 4/28$286
This Orbitz deal was found by Cheapflights users on 4/29. 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 Orbitz is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/162:28 pmONT - ORD
1 stop12h 42mMultiple Airlines
Tue 5/206:00 amORD - ONT
1 stop11h 50mMultiple Airlines
Deal found 4/29$313

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 May 1, 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

Thu 5/15

10:15 pm-2:48 pm

1 stop14h 33m

Chicago Midway

Mon 5/19

8:03 pm-11:59 pm

1 stop5h 56m

$235

OntarioChicago

ONT - ORD

ONTORD

Ontario

Thu 5/15

6:35 pm-5:10 am

1 stop8h 35m

Chicago O'Hare Intl

Thu 5/22

9:50 pm-11:43 am

1 stop15h 53m

$235

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Fri 5/30

4:55 pm-1:05 am

1 stop6h 10m

Chicago Midway

Fri 6/6

12:35 pm-2:45 pm

Nonstop4h 10m

$237

OntarioChicago

ONT - ORD

ONTORD

Ontario

Fri 6/6

7:00 am-1:03 pm

Nonstop4h 03m

Chicago O'Hare Intl

Tue 6/10

12:45 pm-5:25 pm

1 stop6h 40m

$237

OntarioChicago

ONT - ORD

ONTORD

Ontario

Thu 7/17

3:20 pm-11:40 pm

1 stop6h 20m

Chicago O'Hare Intl

Mon 7/21

5:25 pm-9:10 pm

1 stop5h 45m

$242

OntarioChicago

ONT - ORD

ONTORD

Ontario

Thu 8/21

7:10 am-5:00 am

1 stop19h 50m

Chicago O'Hare Intl

Tue 8/26

6:20 am-2:09 pm

1 stop9h 49m

$246

OntarioChicago

ONT - ORD

ONTORD

Ontario

Sat 6/14

4:50 pm-12:32 am

1 stop5h 42m

Chicago O'Hare Intl

Sat 6/21

4:45 pm-9:38 pm

1 stop6h 53m

$249

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Fri 9/5

10:59 pm-9:51 am

1 stop8h 52m

Chicago Midway

Tue 9/9

1:05 pm-7:42 pm

1 stop8h 37m

$257

OntarioChicago

ONT - ORD

ONTORD

Ontario

Wed 6/11

1:15 pm-10:09 pm

1 stop6h 54m

Chicago O'Hare Intl

Sat 6/28

7:40 am-12:17 pm

1 stop6h 37m

$257

OntarioChicago

ONT - ORD

ONTORD

Ontario

Wed 5/28

11:51 am-10:23 pm

1 stop8h 32m

Chicago O'Hare Intl

Wed 6/4

8:00 am-3:50 pm

1 stop9h 50m

$286

Flights are sorted by cheapest round-trip flights first.

Deals found on 4/29

Showing 1-10 of 22 results
1
2
3

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 May.
ProviderPrice AccuracyTrust Score*
ExpediaPrice Accuracy1 starTrust Score*3 stars
FlightHubPrice Accuracy3 starsTrust Score*2 stars
eDreamsPrice Accuracy3 starsTrust Score*3 stars
FlightnetworkPrice Accuracy3 starsTrust Score*3 stars

*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 Flightnetwork to be most consistent on Cheapflights vs. Flightnetwork Users can find the same prices on Ontario-Chicago flight deals on Cheapflights vs. Flightnetwork >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 Flightnetwork the most. Flightnetwork 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

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 April 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 May 1, 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 March 30, 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.

Rainfall in Chicago by month

Plan your trip to Chicago by taking into account the average rainfall totals by month.

In terms of precipitation, rainfall in Chicago ranges from 1.7 - 4.9 inches per month. August is typically the wettest month, when rainfall can reach 4.9 in. January is typically the driest time to visit Chicago when rainfall is around 1.7 in.

Temperature in Chicago by month

Plan your trip to Chicago by taking into account the average temperature totals by month.

If weather is an important factor for your trip to Chicago, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 73.4 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 23.0 F).

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 May 1, 2025.
To help decide which airline to fly from Ontario to Chicago, see what other customers have to say about Alaska Airlines, Southwest and Delta. Users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very good
9,972 reviews

Food

7.1

Boarding

8.1

Crew

8.5

Comfort

7.9

Overall

8.0

Entertainment

7.1

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
9,972 reviews
Alaska Airlines
8.0
Very good
9,972 reviews

Food

7.1

Boarding

8.1

Crew

8.5

Comfort

7.9

Overall

8.0

Entertainment

7.1

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
4,294 reviews
Alaska Airlines
8.0
Very good
9,972 reviews

Food

7.1

Boarding

8.1

Crew

8.5

Comfort

7.9

Overall

8.0

Entertainment

7.1

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
7,934 reviews
Alaska Airlines
8.0
Very good
9,972 reviews

Food

7.1

Boarding

8.1

Crew

8.5

Comfort

7.9

Overall

8.0

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Hawaiian Airlines
7.9
Good
2,409 reviews
Alaska Airlines
8.0
Very good
9,972 reviews

Food

7.1

Boarding

8.1

Crew

8.5

Comfort

7.9

Overall

8.0

Entertainment

7.1

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
8,696 reviews
Alaska Airlines
8.0
Very good
9,972 reviews

Food

7.1

Boarding

8.1

Crew

8.5

Comfort

7.9

Overall

8.0

Entertainment

7.1

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 7 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 $235. Other airlines that can offer you cheap pricing are Southwest, from $237, and United Airlines, from $237. These flights start at 25% 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 ($99), Southwest ($114), and United Airlines ($114).

  • 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 $257 for a flight from Ontario to Chicago. The cheapest flight overall is $113 while the most popular route, (Ontario - Chicago O'Hare Intl) is currently priced at $224.

  • 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 Ontario?

Book flights to Ontario if you plan to visit one of these locations
Merrillville
Hammond
Benton Harbor
Porter
Lansing
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 7 airlines flying from Ontario to Chicago

Discover the top 7 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 May 1, 2025.
AirlineCheapestAverageFlexibilityOn-time
Spirit AirlinesCheapest$74Average$177FlexibilityNo cancel feeOn-time65%
FrontierCheapest$108Average$189FlexibilityNo cancel feeOn-time62%
Alaska AirlinesCheapest$161Average$438FlexibilityNo cancel feeOn-time75%
United AirlinesCheapest$227Average$359FlexibilityNo cancel feeOn-time69%
DeltaCheapest$241Average$398FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$245Average$380FlexibilityNo cancel feeOn-time71%
SouthwestCheapest$246Average$449FlexibilityNo cancel feeOn-time63%

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