$104 Find Cheap Flights from Ontario to Illinois

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Ontario to Illinois departing on 4/17. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult

KAYAK searches hundreds of travel sites at once for deals on flights to Illinois

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Ontario to Illinois.
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Ontario to Illinois.
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Best Illinois Flight Deals from Ontario

Cheapest round-trip prices found by our users on KAYAK in the last 72 hours

Chicago
Chicagononstop$227
Moline
Moline1 stop$289
Peoria
Peoria1 stop$314
Bloomington
Bloomington1 stop$445
St. Louis
St. Louis1 stop$258

Cheap Flight Deals from Ontario to Illinois (ONT-USIL)

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Ontario to Illinois that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.

Recent round-trip flight deals from Ontario to Illinois

Recommended round-trip deals departing in the coming months from the most popular airlines that fly from Ontario to Illinois.
Discover the best prices for you by selecting your travel dates on KAYAK.
Choose your dates
7:00 am - 1:03 pmONT-ORD
4h 03mnonstop
7:55 pm - 10:26 pmORD-ONT
4h 31mnonstop
$227United Airlines
Find Deal
Mon, May 26 - Fri, May 30
4:15 pm - 12:29 amONT-ORD
6h 14m1 stop
7:55 pm - 10:26 pmORD-ONT
4h 31mnonstop
$237United Airlines
Find Deal
Tue, May 20 - Sat, May 24
4:25 pm - 12:21 amONT-MDW
5h 56m1 stop
8:50 pm - 7:25 amMDW-ONT
12h 35m1 stop
$238Frontier
Find Deal
Fri, Apr 18 - Sun, Apr 20
12:59 am - 12:21 amONT-MDW
21h 22m1 stop
6:45 am - 11:59 pmMDW-ONT
19h 14m1 stop
$240Frontier
Find Deal
Wed, Apr 16 - Mon, Apr 21
6:15 am - 3:00 pmONT-ORD
6h 45m1 stop
5:25 pm - 9:10 pmORD-ONT
5h 45m1 stop
$242Southwest
Find Deal
Sat, Jul 19 - Mon, Jul 21
12:00 pm - 10:15 pmONT-MDW
8h 15m1 stop
8:25 am - 2:10 pmMDW-ONT
7h 45m1 stop
$247Southwest
Find Deal
Tue, Apr 29 - Fri, May 9
12:46 pm - 9:02 pmONT-ORD
6h 16m1 stop
5:00 am - 11:07 amORD-ONT
8h 07m1 stop
$248American Airlines
Find Deal
Sat, Jul 26 - Sat, Aug 9
1:15 pm - 10:10 pmONT-ORD
6h 55m1 stop
7:00 am - 12:18 pmORD-ONT
7h 18m1 stop
$257Delta
Find Deal
Thu, Jun 19 - Wed, Jun 25
1:15 pm - 10:10 pmONT-ORD
6h 55m1 stop
2:20 pm - 10:46 pmORD-ONT
10h 26m2 stops
$262Delta
Find Deal
Thu, Jun 19 - Tue, Jun 24
11:59 pm - 8:50 amONT-ORD
6h 51m1 stop
7:34 am - 12:00 pmORD-ONT
6h 26m1 stop
$283American Airlines
Find Deal
Thu, Jul 3 - Mon, Jul 7

KAYAK's insights & trends for Ontario to Illinois flights

Get data-powered insights and trends into flights from Ontario to Illinois to help you find the cheapest flights, the best time to fly and much more.

What is the cheapest Ontario to Illinois flight route?

The cheapest price for flight routes found by users searching on KAYAK in the last 2 weeks for round-trip flights from Ontario to Illinois.
The cheapest ticket to Illinois from Ontario found in the last 72 hours was to Chicago, at $237 round-trip. The most popular route is from Ontario (ONT) to Chicago Midway Airport (MDW), and the cheapest round-trip airline ticket found on this route in the last 72 hours was $342.

What is the cheapest time of day to fly to Illinois?

The average price for all round-trip flights from Ontario to Illinois depending on the time of departure, clicked by users on KAYAK in the last 2 weeks.
The cheapest time of day to fly to Illinois is generally at night, when round-trip flights cost $246 on average. Morning departures are around 61% more expensive than evening flights, on average. The most expensive time of day to fly to Illinois is generally in the afternoon, which is peak travel time and where the average cost of a ticket is $531.

Can I save money by flying with a layover from Ontario to Illinois?

The average round-trip price for all non-stop flights, flights with one layover, and flights with two layovers for the route found by users searching on KAYAK in the last 2 weeks.
No, with an average price for the route of $509, prices are generally cheapest when you fly direct.

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

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Ontario to Illinois, removes the top 0.1% to account for outliers, and then takes the median of all values for each month.
The cheapest month for flights from Ontario to Illinois is November, when tickets cost $200 (return) on average. On the other hand, the most expensive months are March and January, when the average cost of round-trip tickets is $380 and $375 respectively.

What’s the cheapest day of the week to fly from Ontario to Illinois?

The average price of all round-trip flights from Ontario to Illinois clicked on KAYAK for each day over the last 12 months.
If your flying dates are flexible, you should consider flying to Illinois on a Monday, as we generally find the cheapest rates on that day for this route. On the other hand, Sunday is the most expensive day to fly from Ontario to Illinois. For your return ticket, we recommend flying on a Thursday and avoiding Mondays for the best deals.

How far in advance should I book a flight from Ontario to Illinois?

To calculate weekly average prices, KAYAK takes all prices for each week before departure over the last year for round-trip flights from Ontario to Illinois, removes the top 0.1% to account for outliers, and then takes the average of all the values for each week.
To get a below average price on the flight from Ontario to Illinois, you should book around 3 weeks before departure. For the absolute cheapest price, our data suggests you should book 4 weeks before departure.

Good to know

Low season

February

High season

June

Cheapest flight

$104
Best time to beat the crowds with an average 14% drop in price.
Most popular time to fly and prices are also 1% lower on average.
Flight from Ontario to Chicago Midway Airport

FAQs - booking Illinois flights

  • How does KAYAK find such low prices on flights from Ontario to Illinois?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from Ontario to Illinois.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Ontario to Illinois?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight from Ontario to Illinois is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Ontario to Illinois?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly from Ontario to Illinois with an airline and back with another airline.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Ontario to Illinois?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying from Ontario to Illinois up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

See more FAQs

Top tips for finding cheap flights to Illinois

  • Looking for a cheap flight? 25% of our users found tickets from Ontario to the following destinations at these prices or less: Chicago $229 one-way - $436 round-trip

Top 5 airlines serving from Ontario to Illinois

 
See real verified KAYAK customer reviews for airlines flying from Ontario to Illinois. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from Ontario to Illinois? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
8.0
SouthwestOverall score based on 4273 reviews
8.6Crew
8.1Comfort
7.1Food
8.2Boarding
7.6Entertainment
Airline reviews

I liked the crew member who gave flight instructions on "in case of a problem:. The seats are so small that only a young teenager could sit in middle seat.

8.0 ExcellentCarolynn, Mar 2025SMF - KOA
Read more Southwest reviews

I liked the crew member who gave flight instructions on "in case of a problem:. The seats are so small that only a young teenager could sit in middle seat.

Great flight staff. Ease of boarding. Overall, very uneventful and easy trip.

Flight was awfully bumpy and landing was a bit jolting. I was in the restroom when snacks and drinks were served and was not asked if i wanted any. I had to ask for water finally.

Employees were kind and funny, as always! Flight was late but no announcements were made for people with tight connections to help them transition quickly. No service due to turbulence.

I recently flew Southwest from San Jose to Honolulu. I was very impressed with the flight crew, especially the flight attendant in charge of the front of the plane. She came through the aisle at least five times for drinks and water, and two times for snacks. I have not seen such service since I flew first class. Also, for the first time, they gave us the correct baggage claim number, and the luggage came out quickly. I can't wait for Southwest to have assigned seating! I absolutely hate the Cattle Call boarding procedure and the mad dash to get seats and overhead bins. However, the boarding was efficient.

We had a nice flight. Boarding was easy, our seats were comfortable and the on board service was pleasant.

Service was great, boarding and exiting went smoothly, and the flight was very pleasant.

Was as expected. Crowed planes. Too many carryons delaying takeoff. But the ride only took an hour and saved me a lot of time SFO is a not a great airport.

Was as expected. Crowed planes. Too many carryons delaying takeoff. But the ride only took an hour and saved me a lot of time SFO is a hell hole of an airport. It is the new LaGuardia. Everything Cobbled together. Security gates closed. Terri directional signage

I used to fly SWA all the time. I know the crew has their little acts that are often fun, and entertaining. On this flight one of the crew was just not nice. Very surprising.

Thank you for not flipping the plane on the run way. You guys get a 5 star rating for the flight!!!

Boarding is, as it always is… horrible. Gate lice. Slow moving zones. Too many people with carry ons

It was terrible, if they ran flights on time it would make a big difference.

Delta seems to be improving in many areas, except they are super bad with the food available. Bring back normal food service on long flights.

I actually received a notification from kayak on email but not one by text from Delta when my departure gait changed and I almost missed my flight

New boarding doesn't make sense. Filling front first is slow.

Delta flight was great from the check in all the way to arrival. However, I had a very bad experience. I requested a wheelchair and the wheelchair employee that went to pick me up from the plane in Boston to bring me to the baggage claims told me I have to pay him. I was under the impression that it was a free service and I usually give tips but the person forced me to pay and since I said no because I was upset with his demand when my daughter walked in to pick me up he demanded payment from my daughter who paid him thinking maybe now it is a charged service.

Horrible. Grateful to be alive but spent 13 hours at airport only to return back to my familys house and flight changed to next day. They tried to fix a part on plane, had no back up plane and after 10 hours , reattempted the flight and it STILL wasn't fixed. We got a meal voucher and rescheduled flight but there should be some other compensation for the 15 hours spent in airport

5 hour delay. They blamed the weather but it was the computer issues they had been dealing with for days.

My seat was changed at the last minute and I was moved to the last row, right next to the bathroom despite selecting my seat well in advance. I was also made to check my carry on due to space but when I got on the plane there was significant empty overhead space. Picking up my carry on from the luggage carousel added time to my trip which had already been extended due to delay.

Overall poor for me I paid extra for seats with leg room and my regional flights exit row seats have less leg room then the others that's money that could have been saved and on my final flight home the flights air was not operating it was unbearably hot in the cabin I will be contacting United and filing a DOT complaint

There's just no way to sit fully upright and comfortably in these seats. There needs to be 2 more inches of room, and that's not something that only one person on the flight needs - the whole flight needs 2 more inches of room. If that means you sell 6 less seats, so be it. It's too close for anyone. Forcing people to pay for "premium" economy just to get "barely enough space to breathe" isn't really an answer to that.

The crew were very nice. The Chocolate is good and v there’s no entertainment. Thanks

The crew were very nice. I would have appreciated a pillow for comfort. I had a special meal that was sloppy, but the salad was great. Thanks

The plane was in Moline all night. Consequently, we assumed an on time departure at 8:15am. Unfortunately, and as is the normal case with United in Moline, we departed 2.5 hours late. When the crew came, it was discovered that there was very little heat in the plane. Seems this should have been checked hours before the crew arrived. Then when we boarded and the plane was to be de-iced, the United de-icing truck was not working! We awaited the American Airlines truck. All of this caused us to miss our connection in Chicago. My suggestion is never take United Airlines flight from Moline. We have been disappointed 80% of the time and have vowed to not take United again from Moline.

Flight was delayed two hours. No snacks and no tv screens. My bag got stuck in Chicago

The aircrew was solid, the flight was chill, I had no issues. The gate agent was not the best. I was trying to use a military bag upgrade to move my bag from under the seat to the overhead bins and he told me there’s no overhead bins on the plane, argued with me why booking put a military member in basic economy (I don’t really understand this) and made it an issue to even try to help me stating I’d have to call reservations to get a bag upgrade. When every other agent with United can add it at the gate, this man couldn’t be bothered.

They canceled our flight and left us stranded to figure it out

Everything was very good. Was able to change a make run flight leaving on direct earlier in the app -seamless!!! Well done

Being stick waiting for gate at ORD cause me to almost miss my connecting flight…being deaf United made no no effort to keep me updated as I couldn’t hear the PA

Crew professional. Easy bag drop off. On time. Good entertainment.

Everything was great. Boarding, early departure, early arrival, and deplaning were smooth. Smooth flight.

Per usual, flight status, staff courtesy and professionalism were excellent

Everything was on time, we arrived early, everything worked well.

The only thing is if Wi-Fi is available after you land and taxi to the gate. It takes forever to get to the gate, and having the Wi-Fi continue would be great to bide the time at least 5 minutes before you arrive at the entrance. That is my only comment; otherwise, everything was good.

Had to wait on pilot and crew to depart and had to wait to arrive at the gate because they only had 2 crews working. Delays, delays....Planes just keep getting smaller and tighter and they nickle and dime for everything. When will an airline actually wake up and make flying more enjoyable?

Seating was horrible. Small seats. Access to flight information and extras very iser unfriendly. Kept losing internet after paying for it. Staff in madison was as unprofessional and unhelpful.

Delayed due to no crew. On a major holiday travel day.

Other than being delayed 5.5 hours and having to get a hotel because I missed my connecting flight, it was an okay flight. No in-flight Wi-Fi or entertainment.

It was nice being on a flight that had working wifi. The boarding was quick - why don’t all airlines have small boarding groups window to aisle? Makes so much sense!!! I was disappointed to be the first person stopped to have to gate check my carryon. Especially when there was plenty of overhead space at the back! But I get it…keeps it moving. Crew was nice.

Frontier had yet another flight cancellation. Have never made a complete round trip with this airline without at least one leg getting cancelled. Miserable flights - dirty, uncomfortable planes that apparently always have issues since I've had multiple delays and cancellations with them.

Flight was delayed 3 times, would have been nice to have received text message instead of email notifications. Frontier app wasn’t even updated accordingly, no gate number disclosed. No agent at front desk of gate to inform of delay. Very confused and left if the dark

The flight itself was ok and the pilot was very communicative. However, our flight was delayed for almost 3 hours, the gate was changed 3 times and there was no communication as we were waiting. The flight staff was overall a little crabby...I understand as they probably had a long day but we all did.

They changed the timing , first delayed by 4 hours then went back to 40 mins late, we had to run back to airport to not miss our flight. This is ridiculous

No frills for sure. No gate announcements about flight delay, not even water to drink on the flight.

After waiting several minutes to be acknowledged by 3 employees on their phones, was told we had missed our flight because the doors were closed at that literal moment. Had they given any actual service or help while we were standing there we would have been on with time to spare. More than 10 people were turned away in this fashion claiming there was no way they could let us on the plane, even though it was still sitting connected to the terminal. After the desk agents let us know they didn't care about the situation we were forced to pay more than twice the price of our original tickets as no credits were given for the price of the "missed" flight. And the icing on the cake was after being treated poorly, fleeced for another few hundred dollars for new tickets? We waited on the next plane for 25 minutes passed the "doors closed" time, letting almost an extra dozen passengers on board. You're company has lazy, disinterested employees and your lack of any real help will ensure this was the first and last time we fly Frontier. Awful.

I loked walking out on the tarmac to board and no first class. I didn't like that they have no snacks or onboard wifi to bide your time.

It was a redeye flight, so every passenger just wanted to sleep, but through the entire flight, the flight crew made announcements over the loudspeaker at maximum volume every few minutes making sleep impossible. For example: it’s 2am, and the crew decides to give an extremely detailed announcement about snacks and beverages for sale. And 3am is the perfect time to wake up everyone with a lengthy announcement about how to get a coffee refill and how to take advantage of new offer from frontier for a credit card.

The takeoff was the smoothest I've ever experienced on any airline and this is the first time I've flown on frontier so this was an extremely pleasant surprise!

A lady asked to stop the flight after the tunnel pulled away and we began to depart a flight that was already hours late. The attendance respectfully stopped the the plane and had the tunnel return. After the tunnel returned the passenger claimed to have changed her mind . The tunnel was then put in reverse and the passenger remained on the plane .. They should have sent the sick passenger off the plane like initially replaced. They existed a couple off the plane prior to that situation.. So.. all and all.. it was a long and flight.. .

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