$37 Find Cheap Flights from Denver 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 Denver to Illinois departing on 1/30. 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
1 adult, Economy, 0 bags

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 Denver to Illinois, as well as popular online travel agencies
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Denver to Illinois, as well as popular online travel agencies
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Cheap Flights from Denver to Illinois

Cheapest round-trip prices found by our users on KAYAK in the last 72 hours
Chicago
Chicagononstop$115
Moline
Moline1 stop$229
Peoria
Peorianonstop$155
Bloomington
Bloomington1 stop$339
Champaign
Champaign1 stop$465
Springfield
Springfield1 stop$308
St. Louis
St. Louisnonstop$101
Decatur
Decatur1 stop$360
Chicago
Chicagononstop$115
Moline
Moline1 stop$229
Peoria
Peorianonstop$155
Bloomington
Bloomington1 stop$339
Champaign
Champaign1 stop$465
Springfield
Springfield1 stop$308
St. Louis
St. Louisnonstop$101
Decatur
Decatur1 stop$360

Book Cheap Denver to Illinois Plane Tickets

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Denver 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.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from Denver to Illinois

Wed, Nov 12 - Sat, Nov 15
Frontier Logo
6:00 am - 9:07 amDEN-STL
2h 07mnonstop
Frontier Logo
7:45 pm - 9:13 pmSTL-DEN
2h 28mnonstop
$101Frontier
Find Deal
Wed, Nov 12 - Sat, Nov 15
Frontier Logo
6:00 am - 9:07 amDEN-STL
2h 07mnonstop
Frontier Logo
7:45 pm - 9:13 pmSTL-DEN
2h 28mnonstop
$102Frontier
Find Deal
Mon, Jan 12 - Mon, Jan 26
United Airlines Logo
4:15 pm - 7:51 pmDEN-ORD
2h 36mnonstop
United Airlines Logo
2:36 pm - 4:34 pmORD-DEN
2h 58mnonstop
$155United Airlines
Find Deal
Sat, Jan 10 - Thu, Jan 29
Southwest Logo
5:30 am - 9:00 amDEN-MDW
2h 30mnonstop
Southwest Logo
8:10 am - 10:00 amMDW-DEN
2h 50mnonstop
$155Southwest
Find Deal
Mon, Dec 29 - Mon, Jan 5
Allegiant Air Logo
5:54 pm - 8:51 pmDEN-PIA
1h 57mnonstop
Allegiant Air Logo
3:38 pm - 5:04 pmPIA-DEN
2h 26mnonstop
$155Allegiant Air
Find Deal
Wed, Dec 10 - Sat, Dec 13
United Airlines Logo
5:35 pm - 9:08 pmDEN-ORD
2h 33mnonstop
United Airlines Logo
6:15 pm - 8:04 pmORD-DEN
2h 49mnonstop
$157United Airlines
Find Deal
Mon, Dec 29 - Mon, Jan 5
Allegiant Air Logo
5:54 pm - 8:51 pmDEN-PIA
1h 57mnonstop
Allegiant Air Logo
3:38 pm - 5:04 pmPIA-DEN
2h 26mnonstop
$163Allegiant Air
Find Deal
Mon, Dec 8 - Mon, Dec 22
Southwest Logo
8:00 am - 11:25 amDEN-MDW
2h 25mnonstop
Southwest Logo
10:30 pm - 12:10 amMDW-DEN
2h 40mnonstop
$177Southwest
Find Deal
Wed, Nov 12 - Sun, Nov 16
American Airlines Logo
6:23 am - 4:40 pmDEN-PIA
9h 17m1 stop
American Airlines Logo
4:23 pm - 11:56 pmPIA-DEN
8h 33m1 stop
$269American Airlines
Find Deal
Thu, Feb 19 - Sun, Feb 22
American Airlines Logo
5:57 pm - 11:46 pmDEN-MLI
4h 49m1 stop
American Airlines Logo
3:34 pm - 10:38 pmMLI-DEN
8h 04m1 stop
$279American Airlines
Find Deal
Booking Insights

KAYAK's insights & trends for Denver to Illinois flights

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

What is the cheapest Denver to Illinois flight route?

Data is based on round-trip flight searches on KAYAK over the past month.

The cheapest ticket to Illinois from Denver found in the last 72 hours was to Peoria, at $77 round-trip. The most popular route is from Denver (DEN) to Chicago O'Hare Intl Airport (ORD), and the cheapest round-trip airline ticket found on this route in the last 72 hours was $112.

Can I save money by flying with a layover from Denver 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 $271, prices are generally cheapest when you fly direct.

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

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Denver 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 Denver to Illinois is February, when tickets cost $185 (return) on average. On the other hand, the most expensive months are May and April, when the average cost of round-trip tickets is $226 and $219 respectively.

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

The average price of all round-trip flights from Denver to Illinois clicked on KAYAK for each day over the last 12 months.

If you are looking for a flight deal from Denver to Illinois, look for departures on Fridays and avoid leaving on a Sunday, as it's usually the priciest day. When flying back from Illinois, Wednesday is the cheapest day to fly and Sunday is the most expensive.

How far in advance should I book a flight from Denver 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 Denver 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 Denver to Illinois, you should book around 4 weeks before departure, which saves you about 32% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 5 weeks before departure.

Good to know

Low seasonFebruary
Cheapest flight$37
Best time to beat the crowds with an average 9% drop in price.
Most popular time to fly and prices are also 6% lower on average.
Flight from Denver to St. Louis

Flights from Denver to Illinois: the best tips from KAYAK users

Insights shared by verified travelers who flew the route from Denver to Illinois 
AdamFlew with SouthwestDEN-ORDOct 2024
Arriving T5 at ORD on Southwest is often a LONG walk, with no moving walkways going out, to baggage claim / pickup.
BrianFlew with United AirlinesDEN-ORDJan 2024
Big airport. Make sure you have enough time between flights for rest, eating, etc…

FAQs - booking Illinois flights

  • How does KAYAK find such low prices on flights from Denver 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 Denver to Illinois.

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

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight from Denver 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 Denver 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 Denver 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 Denver 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 Denver to Illinois up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

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

    The cheapest time of day to fly to Illinois is generally at night, when round-trip flights cost $198 on average. Morning departures are around 2% cheaper 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 $631.

Top tips for finding cheap flights to Illinois

  • Looking for a cheap flight? 25% of our users found tickets from Denver to the following destinations at these prices or less: Chicago $139 one-way - $226 round-trip

Reviews of the top 5 airlines serving from Denver to Illinois

 
See real verified KAYAK customer reviews for airlines flying from Denver 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 Denver 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 4242 reviews
8.1Boarding
7.0Food
8.6Crew
7.5Entertainment
8.0Comfort
Airline reviews

Connecting flight is on time and boarding was a breeze!

10.0 ExcellentGabriel, Sep 2025DEN - SMF
Read more Southwest reviews

Connecting flight is on time and boarding was a breeze!

Excellent. Would encourage Southwest to keep current boarding procedures with free style seating. Makes for a fantastic experience

WiFi did not work. For as outrageous as these flights cost, when they’re advertised with certain services/ features they should be in working order

Worst experience I had on Southwest. Still better than most, but the seating was barely tolerable.

It was okay. The plane was delayed from earlier in the day, but they kept updating the departure time, sometimes later, sometimes earlier. That was stressful. Once we finally got on and took off, it was fine. I was supposed to have a connection in Chicago to Los Angeles, and the time for so late I was rebooked to arrive in LA 3 hours late. The departure time to Chicago later became early enough to have taken my original connection and arrive earlier but that wasn't an option.

Everything was on time. I was disappointed by the front section female, African American flight attendant. I did not see her name tag or would have identified by name not race. As passengers moved to the bathroom early in flight, she would say with a disdainful tone “I have to say the seat belt light is on” then go back to her book. Better trained flight attendants say something like be careful the seat belt light is on.

I would have liked to arrive on time - not 5 hours late!

1.5 hour delay, poor service, no compassion from the crew. Terrible experience

Our flight was diverted from being a non-stop to getting within 150 miles and requiring another plane. We heard 4 or 5 different versions from SW as to why we had to stop, then wait for a replacement plane. Five hour delay, weather did not come up as a single excuse.... communication was not clear and well explained. No one really took charge!

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.

Crew seemed a bit cranky. No seatback screens. But boarding was efficient and on time and we arrived early.

See previous note about the passenger in Denver who threw my husband's bag out of the overhead bin in order to maker room for his own. And the flight attendant back up the new passenger.

Terrible. They wouldn't allow me on my flight on the 14th..

Impressed with the service despite turbulence because of the weather. Both flights arrived before their scheduled times.

Great experience…left a bit behind schedule but made up fir that in the air and landed 10 minutes early 😁

Electric plugs didn't work. Entertainment system wasn't working

The design of the light switch on the arm rest is ridiculous.

The gate attendant let me walk right by her with a bag too big for the overhead compartment

Overall, it was a good experience. Boarding was good and there was plenty of overhead bin space for everyone’s carryons (even when we boarded toward the end). Only improvement would be to offer trash service more regularly.

David went above and beyond to make our flight the best that it could be

It was good..clean, comfy seat. Friendly warm welcoming crew. Was able to check my cabin luggage at the gate which I was able to pickup in a decent time from baggage claim. The app gave all updates from delays to baggage claim info. Overall smooth flight.

Terrible. Our luggage was delayed and couldn’t be delivered for several days. We got bad information from the airline agents at baggage claim. We had to pick up our car so we wouldn’t be charged for an extra day. We got lost in the maze of airport parking. The baggage claim agents didn’t offer us any compensation for our extra time and expense. We are tired, hungry and very frustrated.

It was a typical flight. We had a delay which seems to be the normality now. And we had no in flight service due to conditions.

After we landed we sat on the tarmac for 1.5 hours waiting to get to our gate. Ridiculous.

Terrible. Flight delayed for more than 8 hours with only a $12 meal voucher provided for the inconvenience. The airplane did not have breaks on arrival yet they still made us go through the motions and board on time knowing we could not take off then sit for 40+ minutes before having to get of the time. A complete waste of my time. I cannot believe they can stay business with these shenanigans. I’ll avoid this company like the plague moving forward as the lack of accountability is disgraceful.

This was the best 2 flights I have had with American out of SGF. Great crew both flights.

Excellent - explanations were clear staff was nice and flight was comfortable

Lost bag and 2 days no word leaving for cruise no clothes or stuff

Don’t know they cancelled the flight day before I was to leave. They sent a email at 9:00 pm at night saying they cancelled. That is the smooth way to say we don’t want your business! I think they didn’t have enough people booking so they cancelled the flight! It’s all about the money anymore there is no honesty in business.

Any flight to ORD after about 2pm this summer has been challenging. Flight was delayed getting in (coming from ORD) and that led to it not leaving before a ground stop due to lightening before they could fuel the plane, and so forth. They made up some time but we were still late in arriving at ORD, and that led to missed connections.

I liked how when I got on board how fast we ended up taking off but what I truly disliked was how uncomfortable the seats were. There was truly never a time that I could ever get comfortable during both of my flights. The seats could get away during shorter flights but flights 3 hour plus makes it hard to enjoy.

The crew was great and the flight was very smooth. Can’t really judge food since I did not get any because it costs money. The seat was comfortable for what we bought. Thanks!

Crew was great. No entertainment and food and beverage was for purchase only, even water

It was canceled. The flight wasn’t rescheduled, everyone had to figure out their own new arrangements. They said we would get refunded our original fare and receive an additional $150. We received links for $100 only and they expired before we could activate them.

The plane had originated in Las Vegas at 6:30 in the morning and flew to Moline where we boarded. The flight left around 12:30 PM and there were no boxed snacks available and many of the alcoholic beverages were unavailable. I would find it hard to believe that that many of the passengers coming from Las Vegas at 6:30 in the morning, drank and ate that much of the items. I can only come to the conclusion that someone failed to stock the plane for the round-trip. This is a huge revenue failure for the airline and disappointment for the passengers. The flight crew did not seem happy to be there and did not engage with passengers. Allegiant you can do better.

They did not let my husband on the plane with our service animal at the last minute. Do NOT fly this airline with a service animal!

Tight! Seats are not designed for those of us who wear extra-large clothes.

The non-stop flight from Grand Rapids was excellent. I neither expected or needed a budget flight and Allegiant made the trip easy and for an affordable price, Arriving at the Mesa Airport (AZA) is a delight compared to the international airport. For our return flight, we were able to arrive 75 minutes before the flight, return the rental car, check our bag and make it to the gate in plenty of time. That would never happen at most airports.

Easiest flights I’ve ever taken. Plane was comfortable without overly crowded seating.

Terrible. Still have not received the refund from them. They sent it to some account that I don't even know. Spoke with costumer service and they are unable to help.

The single worst check in experience I could imagine. I’ll never do any business with Frontier or any affiliated company

Too many extra fees, uncomfortable, little leg room. Will not recommend this airline.

Frontier is the Walmart of airlines. Frontier has removed adjustability and comfort from their seats to make the flight lighter and save gas. This makes it impossible to sleep on their flights. Their customer service is abysmal. Once, I bought a drink on the plane, and they swiped my credit card on the plane to pay for it. Then I got three weeks of daily notices from my bank telling me they tried to charge the wrong card number over and over again. I tried to call them, but they removed the ability to actually talk to someone that can resolve such a problem from their company to cut corners. The only way to talk to someone in person is to go to the check-in counter at the airport (40 minutes drive from my house). Eventually their system gave up on trying to charge the card, after 21 days of repeated tries. They don't pad their prices even a little to handle customer service issues like missed flights. They also have a blanket policy preventing helping you reschedule a missed flight if their system says you "cancelled" your own flight online. This is a major problem because their website is broken on mobile devices, the only web browser you have at the airport when their gate staff tell you that you have to reschedule your own missed flight online because they can't help you. I tried to reschedule my flight on my android device and instead, their website crashed and "cancelled" my missed flight. When I got to the counter, the agent argued with me for 5 minutes insisting that I intentionally cancelled my own flight (implying I had to buy another flight). She missed the point: the problem was that I could not buy another flight because their website is broken. I left to avoid more conflict with the "customer service" agent. I tried to redress my issue with their only other "customer service" chanel available: the contact form on their website. The response I got was more of the same: you cancelled your own flight, according to our website / computer records, therefore we won't help you. I was trying to explain the problem with their broken website that cost me hundreds of dollars by crashing / malfunctioning and resulting in a cancelled flight, but they only had deaf ears for this problem. Worst customer service I have ever experienced. I will never buy another Frontier flight again, because it is a risky, painful move that I will likely regret often.

What I expected, nickeled and dined and a frontier flight attendant loudly complained about her job and lack of communication as she headed to the gate on her cell phone. Not professional.

Severe turbulence. Captain never came on to reassure passengers after things settled down.

I’m not gonna fly Frontier Airlines because booking is not an option. No water or food is for high price, not equipped for health emergency incompetent crew for emergency services. Cheap airline shows it is cheaper in all service categories. Boarding is the best of all airlines!

We were delayed three times ,and that destroyed my plans, and reservations

Very bad! No good service delayed my second connection flight

Frontier is terrible. Paid for exit row, not given exit row, refused to refund fee.

2 hour delay due to late plane, wrong size plane causing overbooking, and people getting off and on the plane after boarding was completed.

Everything you need to know for your flight from Denver to Illinois

Information on your arrival and departure airports

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