$40 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 6/11. 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.
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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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Flights Deals

Best Illinois Flight Deals from Denver

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

Chicago
Chicagononstop$104
Moline
Moline1 stop$229
Peoria
Peorianonstop$113
Bloomington
Bloomington1 stop$339
Champaign
Champaign1 stop$441
Springfield
Springfield1 stop$367
Decatur
Decatur1 stop$358
St. Louis
St. Louisnonstop$116
Chicago
Chicagononstop$104
Moline
Moline1 stop$229
Peoria
Peorianonstop$113
Bloomington
Bloomington1 stop$339
Champaign
Champaign1 stop$441
Springfield
Springfield1 stop$367
Decatur
Decatur1 stop$358
St. Louis
St. Louisnonstop$116

Cheap Flight Deals from Denver to Illinois (DEN-USIL)

 
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.

Recent round-trip flight deals from Denver to Illinois

Recommended round-trip deals departing in the coming months from the most popular airlines that fly from Denver to Illinois.
Discover the best prices for you by selecting your travel dates on KAYAK.
Frontier Logo
7:59 pm - 11:44 pmDEN-ORD
2h 45mnonstop
Frontier Logo
7:00 am - 8:53 amORD-DEN
2h 53mnonstop
$104Frontier
Find Deal
Tue, Aug 5 - Sat, Aug 9
Frontier Logo
5:26 pm - 8:53 pmDEN-MDW
2h 27mnonstop
Frontier Logo
12:35 pm - 2:23 pmMDW-DEN
2h 48mnonstop
$104Frontier
Find Deal
Thu, Jun 12 - Mon, Jun 16
Allegiant Air Logo
5:56 pm - 9:00 pmDEN-PIA
2h 04mnonstop
Allegiant Air Logo
3:48 pm - 5:06 pmPIA-DEN
2h 18mnonstop
$113Allegiant Air
Find Deal
Fri, Jun 20 - Mon, Jun 30
Southwest Logo
7:25 pm - 10:50 pmDEN-MDW
2h 25mnonstop
Southwest Logo
5:15 am - 6:50 amMDW-DEN
2h 35mnonstop
$151Southwest
Find Deal
Wed, Jun 4 - Wed, Jun 11
Southwest Logo
11:10 am - 4:05 pmDEN-MDW
3h 55m1 stop
Southwest Logo
9:25 pm - 11:10 pmMDW-DEN
2h 45mnonstop
$157Southwest
Find Deal
Wed, Jun 4 - Wed, Jun 11
American Airlines Logo
5:32 pm - 9:22 pmDEN-ORD
2h 50mnonstop
American Airlines Logo
6:48 am - 8:22 amORD-DEN
2h 34mnonstop
$160American Airlines
Find Deal
Thu, Sep 4 - Sun, Sep 7
American Airlines Logo
7:27 am - 10:59 amDEN-ORD
2h 32mnonstop
American Airlines Logo
6:48 am - 8:22 amORD-DEN
2h 34mnonstop
$169American Airlines
Find Deal
Thu, Sep 25 - Mon, Sep 29
United Airlines Logo
7:07 pm - 10:41 pmDEN-ORD
2h 34mnonstop
United Airlines Logo
5:00 am - 6:43 amORD-DEN
2h 43mnonstop
$173United Airlines
Find Deal
Wed, Jun 25 - Mon, Jun 30
Allegiant Air Logo
6:08 pm - 9:12 pmDEN-PIA
2h 04mnonstop
Allegiant Air Logo
4:00 pm - 5:18 pmPIA-DEN
2h 18mnonstop
$196Allegiant Air
Find Deal
Fri, Jun 13 - Mon, Jun 16
United Airlines Logo
8:40 pm - 11:59 pmDEN-STL
2h 19mnonstop
United Airlines Logo
4:32 pm - 6:01 pmSTL-DEN
2h 29mnonstop
$210United Airlines
Find Deal
Wed, Jun 11 - Tue, Jun 17
Useful Info

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?

The cheapest price for flight routes found by users searching on KAYAK in the last 2 weeks for round-trip flights from Denver to Illinois.

The cheapest ticket to Illinois from Denver found in the last 72 hours was to Peoria, at $78 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 $155.

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 $585, 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 September, when tickets cost $140 (return) on average. On the other hand, the most expensive months are March and December, when the average cost of round-trip tickets is $212 and $212 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, Thursday 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 3 weeks before departure. For the absolute cheapest price, our data suggests you should book 5 weeks before departure.


Good to know

Low seasonFebruary
High seasonMay
Cheapest flight$40
Best time to beat the crowds but there is an average 3% increase in price.
Most popular time to fly and prices are also 3% 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 $168 on average. Morning departures are around 2% 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 $687.

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 $124 one-way - $256 round-trip

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 4294 reviews
7.1Food
7.6Entertainment
8.6Crew
8.0Comfort
8.2Boarding
Airline reviews

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

4.0 OkayAnonymous, Apr 2025DEN - SEA
Read more Southwest reviews

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.

I really like open seating. I hate that I've heard this is going away. This is one of the unique things that makes Southwest my goto choice.

It seems as though the provisions are even less. Although SWA used to be an economy Airline, that isn't really the case anymore. I paid over $700. for a round trip to Denver and I could have flown just about any airline for the price. The drinks are now in a 6-ounce cup and with ice I'm sure a can would fill more than 2 cups. However, I am very proud of SWA for using paper rather than continuing to contribute to the millions of plastic cups being used each day. I've thought of this fr many years and am so glad to see it come to fruition, if not by only SWA so far.

My original flight was extremely delayed but I was able to join the standby list for an earlier flight. I was grateful for this feature but I wish I could’ve gotten my standby confirmation sooner.

I like that it was on time and the staff was friendly.

No space for our carryon and needed to check at plane before boarding !

Flight was ok. Boarding wasn’t fun. Flights were delayed by 12 minutes on each leg.

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

No food service almost missed because of first flight delays

Had a hard time finding my assigned seat. No attendants to assist.

The negative was the wait at the airport coming back. I checked my bags in, an hour before boarding and I get the notification that my flight was delayed. Rather had gotten the notification while I was at the hotel. Then it was delayed 3 x’s. Ugh!

Plane still had screens for watching movies. Good selection too.

There was no air on the plane and it was very hot.

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.

I didn’t like it at all. I miss my second flight because of the delay on Allegiant Air now I m stuck in MCO.

Good, but a bit late on take off after loading. Don't like charging for carry ons!

First time flying with them and will definitely fly again in the future. Crew was so nice and friendly, fought was seamless. They are simple planes, no entertainment, but it’s fine for a short flight or if you have personal devices Rates are competitive, and they did so well with keeping the flight on time after a tropical storm, where other airlines had delays and cancellations.

They boarded passengers that sat in the back of the plane first, making boarding very efficient.

I didn't even take this flight. My plans changed and I couldn't get ahold of customer service and the website kept breaking down during the attempt to change the flight. I wound up taking another airline entirely and eating the cost.

The worst flying experience ever 3 delays. No accommodations. Had to deboard the plane after being delayed.

Posted a 20minute delay but didn’t delay at all. Caused boarding issues and confusion. Also, didn’t release baggage. Took over an hour and 20 minutes to get luggage.

Flight was good, boarding was a breeze, flight attendants were friendly and professional. There was a medical issue with another passenger and the crew handled it in a calm and professional way.

Any sort of gluten free snack option would be nice

To start, I’d like to say that every American Airline personnel I interacted with on the ground, especially flight crew, was very friendly and did their best to help me out. Despite this, however, my experience with the airline was an entire mess. The 7:19 PM flight was heavily delayed due to weather, and pushed to 10:30 AM the next morning. Because of this, I had to spend the night inside of the airport. At some point later in the night, I got an email saying that the flight had been canceled. I called the support number, and the representative on the other line told me that the flight was still on and that I didn’t need to rebook. The next morning, no one came to the gate to open the door for the crew until almost 11 AM. By this time the flight crew had been waiting for over an hour, and they had called management to get someone to open the door for them multiple times. Around 11:30, the gate screen had changed to a different flight. I ended up buying a last minute ticket with Southwest airline just to get to Chicago, because the next flight with American wasn’t until 7:19 pm that day. Now, earlier that morning my suitcase had been sent ahead of me to ORD. I went to baggage claim to ask them if I could have my suitcase forwarded to where I was staying. The representative at SDF baggage claim said they could and put the claim in for me. As I was going back through TSA, I got an email that the airline had found my suitcase, but the next step was to send it BACK to SDF. I called the airline support number again, and I made it clear that my suitcase needed to stay in Chicago and to not come back to SDF. The representative told me that they would hold my suitcase at ORD and that it wasn’t going to be forwarded anywhere. Once I got there, I found that they had loaded my suitcase onto a plane to send it back to SDF. Thankfully, I had gotten to the baggage claim counter in time for them to put in a request to bring my suitcase back up. My refund with the airline is processing already, but because of this entire experience and miscommunication at every turn of the way, I will not book with American Airlines in the future.

The plane was late and then sat on the runway for almost 45 minutes before taking off.

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

Crew was late. Baggage was late. 2hs inside the plane waiting fro de-icing and traffic. A 3:30hs flight ended up being almost 6hs inside the airplane.

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?

Everything went as planned. Crew was great. Seats were still not that comfortable.

they delayed my flight which ended up, causing my layover flight to leave without me, resulting in me missing a flight and having to stay overnight in Houston international. I got no compensation other than a flight to my original location only a day later. i’ve never experienced such a unprofessional situation

The seats were extremely hard and uncomfortable, even for a budget airline.

Boarding was very well executed. Got my bag right away.

Overall experience good. There was no food and seats were not terribly comfortable.

There was nothing to like, flight delayed had to move to different departure areas, disorganized to say the leasr

There were a lot of issues every step of the process. Check in, security, boarding, and dealing with luggage. Plus the money you think you are saving you end up using in hidden fees.

The flight attendant was arguing with a passenger before takeoff. The passenger was frustrated but the flight attendant should have handled it with grace, but instead she was nasty and rude. The seats were comfortable and the flight was uneventful. I wish we didn’t have to pay for drinks or snacks but that’s what you get with a budget airline.

Booked two aisle seats and were switched to an aisle and middle. Not happy.

I fly Frontier often and generally don't have any issues. For some reason, the Denver to Houston's George Bush Intercontinental (IAH) flight always needs to wait on the tarmac in Houston because a gate is not available after landing. I've been stuck for as little as 15 minutes and as much as a little over an hour. I know only fly the Frontier Denver to IAH route when there is not an available flight to Houston Hobby (HOU).

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

Information on your arrival and departure airports

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