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$62+ Cheap flights from Illinois to Ontario (ONT)

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 1/30. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — ONT
nov. 27 — dic. 41
jue. 11/27
jue. 12/4
1 adult, Economy
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Cheap flight deals from Illinois to Ontario

Keep the following information in mind while searching for Illinois to Ontario flight deals. Data was last updated octubre 28, 2025.

Most accurate provider

CheapOair
3 stars

Most trusted provider

CheapOair
3 stars

Round-trip from

$125
(Frontier)

One-way from

$62
(Trip.com)

Popular in

December

Cheapest in

September

Average price

$269

Good round-trip deal

$434 or less

Good one-way deal

$183 or less
Provider with most accurate pricing for Chicago (CHI)-Los Angeles flight deals.
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From Illinois to Ontario
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One-way flight from Illinois to Ontario
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Highest demand for flights based on searches. 9% potential increase in price ($28 potential increase over avg. RT price).
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Cheapest flight prices on average. 3% potential price decrease ($8 potential savings vs. average RT price).
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Average for round-trip flights in October 2025
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Price to beat on a round-trip flight from Illinois to Ontario.
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Price to beat on a one-way flight from Illinois to Ontario.
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Find flight deals from Illinois to Ontario

Cheapest flights from Illinois to Ontario
Explore the most affordable flight options available from Illinois to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on octubre 28, 2025.

This Frontier deal was found by Cheapflights users on 10/28. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
jue. 11/136:00 amORD - ONT
1 stop7h 10mFrontier
jue. 11/131:46 pmONT - ORD
1 stop7h 58mFrontier
Deal found 10/28$125
This Frontier deal was found by Cheapflights users on 10/27. 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.
jue. 11/136:00 amORD - ONT
1 stop7h 10mFrontier
sáb. 11/1512:05 pmONT - ORD
1 stop9h 24mFrontier
Deal found 10/27$130
This CheapOair deal was found by Cheapflights users on 10/26. 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.
jue. 11/136:30 amMDW - ONT
1 stop14h 19mFrontier
sáb. 11/1512:05 pmONT - MDW
1 stop21h 25mFrontier
Deal found 10/26$130
This CheapOair deal was found by Cheapflights users on 10/27. 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.
lun. 11/172:42 pmSTL - ONT
1 stop9h 15mFrontier
jue. 11/2012:23 pmONT - STL
1 stop19h 39mFrontier
Deal found 10/27$130
This Frontier deal was found by Cheapflights users on 10/27. 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.
jue. 12/47:00 amORD - ONT
1 stop6h 09mFrontier
jue. 12/1112:04 pmONT - ORD
1 stop10h 08mFrontier
Deal found 10/27$131
This Frontier deal was found by Cheapflights users on 10/27. 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.
lun. 11/176:00 amORD - ONT
1 stop7h 10mFrontier
lun. 11/171:46 pmONT - ORD
1 stop7h 58mFrontier
Deal found 10/27$145
This CheapOair deal was found by Cheapflights users on 10/27. 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.
lun. 11/1010:43 pmORD - ONT
1 stop23h 59mFrontier
sáb. 11/1512:05 pmONT - ORD
1 stop9h 24mFrontier
Deal found 10/27$150
This CheapOair deal was found by Cheapflights users on 10/28. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
jue. 11/132:42 pmSTL - ONT
1 stop9h 15mFrontier
lun. 11/176:00 amONT - STL
1 stop12h 12mFrontier
Deal found 10/28$150
This Kiwi.com deal was found by Cheapflights users on 10/28. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
jue. 12/44:47 pmORD - ONT
1 stop26h 47mMultiple Airlines
mar. 12/912:30 pmONT - ORD
1 stop23h 28mMultiple Airlines
Deal found 10/28$158
This Priceline deal was found by Cheapflights users on 10/26. 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 Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
jue. 12/47:00 amORD - ONT
1 stop6h 09mFrontier
lun. 12/82:59 pmONT - ORD
1 stop6h 58mFrontier
Deal found 10/26$160
This Kiwi.com deal was found by Cheapflights users on 10/27. 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.
lun. 12/19:22 pmORD - ONT
1 stop16h 05mMultiple Airlines
jue. 12/42:59 pmONT - ORD
1 stop18h 43mMultiple Airlines
Deal found 10/27$164
This Kiwi.com deal was found by Cheapflights users on 10/27. 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.
mié. 12/39:22 pmORD - ONT
1 stop23h 13mMultiple Airlines
lun. 12/82:59 pmONT - ORD
1 stop6h 58mMultiple Airlines
Deal found 10/27$167

Cheapflights Fare Finder

 
Customize your flight search to find flights from Illinois to Ontario 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 octubre 28, 2025.
Use the filters below to find and compare flights from Illinois to Ontario that are best for you.

Fly from

Illinois

Fly to

Ontario

Route

Depart

Return

Price

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

mié. 11/12

7:45 pm-11:10 am

1 stop17h 25m

Ontario

mié. 11/19

12:58 am-6:58 pm

1 stop16h 00m

$130

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

lun. 11/10

9:07 pm-8:42 pm

1 stop25h 35m

Ontario

lun. 11/17

6:00 am-8:12 pm

1 stop12h 12m

$176

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

vie. 11/7

9:07 pm-8:42 pm

1 stop25h 35m

Ontario

lun. 11/10

4:05 pm-9:07 am

1 stop15h 02m

$182

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

lun. 11/3

6:30 am-6:49 pm

1 stop14h 19m

Ontario

mié. 11/5

8:45 am-11:30 am

1 stop24h 45m

$222

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

jue. 11/6

6:30 am-6:49 pm

1 stop14h 19m

Ontario

dom. 11/9

6:45 am-11:30 am

1 stop26h 45m

$228

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

vie. 11/14

9:07 pm-8:42 pm

1 stop25h 35m

Ontario

dom. 11/16

7:44 pm-8:12 pm

1 stop22h 28m

$234

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

vie. 11/7

12:30 pm-11:10 am

1 stop24h 40m

Ontario

dom. 11/9

6:45 am-11:30 am

1 stop26h 45m

$234

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

lun. 11/10

12:30 pm-9:57 pm

2 stops11h 27m

Ontario

vie. 11/14

1:46 pm-12:37 pm

1 stop20h 51m

$240

ChicagoOntario

MDW - ONT

MDWONT

Chicago Midway

jue. 11/6

12:30 pm-11:10 am

1 stop24h 40m

Ontario

lun. 11/10

8:24 am-5:15 pm

1 stop6h 51m

$252

St. LouisOntario

STL - ONT

STLONT

Lambert-St Louis

mié. 12/31

7:43 pm-11:59 pm

1 stop6h 16m

Ontario

lun. 1/5

6:45 am-10:02 am

1 stop25h 17m

$276

Flights are sorted by cheapest round-trip flights first.

Deals found on 10/27

Showing 1-10 of 60 results
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Best time to book a flight from Illinois to Ontario

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

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

Currently, September is the cheapest month in which you can book a flight from Illinois to Ontario (average of $80). Flying from Illinois to Ontario in December is currently the most expensive (average of $151). 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 IL to ONT?

Find hourly flight availability from Illinois to Ontario. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated octubre 28, 2025.

It’s typically best to fly out from Illinois to Ontario in the evening. Doing so could potentially save you 30% on the flight price compared to flying in the morning, which is usually more expensive.

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

Use this chart to determine the cheapest time to fly round-trip from Illinois to Ontario. Price data was last updated on December 16, 2024.

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

Related info for your journey

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

    Located just 3.1 mi from the city center, Ontario (ONT) is the airport most travelers will use when flying to Ontario from Illinois.

  • How long is the flight from Illinois to Ontario?

    For as low as $289, Frontier can have you in Ontario from Illinois in 8h 50m. The distance between Illinois and Ontario is about 1557 mi. This flight may include one or multiple stops.

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

    $117 is the cheapest one-way deal found within the past few days, from Frontier. You may also be able to find cheap deals on Alaska Airlines and Southwest, with prices starting from $159 and $203, respectively.

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

    When deciding which route to take from Illinois to Ontario consider Chicago O'Hare Intl - Ontario, Chicago Midway - Ontario or Lambert-St Louis - Ontario as they are the most popular.

  • What are the cheapest flights from Illinois to Ontario?

    The cheapest flight price from Illinois to Ontario is $232. On average you can expect to pay $535. The most popular route, (Chicago O'Hare Intl - Ontario), can usually be booked for $150.

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

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

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

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

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

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

    Currently, September is the cheapest month in which you can book a flight from Illinois to Ontario (average of $80). Flying from Illinois to Ontario in December is currently the most expensive (average of $151). 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

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Alternative routes for Illinois to Ontario

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Top 5 airlines flying from Illinois to Ontario

Discover the top 5 airlines that operate flights from Illinois to Ontario. 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 octubre 28, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$125Average$220FlexibilityNo cancel feeOn-time62%
American AirlinesCheapest$231Average$583FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$237Average$443FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$256Average$462FlexibilityNo cancel feeOn-time63%
DeltaCheapest$256Average$280FlexibilityNo cancel feeOn-timeN/A

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