$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 3/18. 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.
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Denver to Illinois.
Travelers love KAYAK
41,299,237 searches in the past 7 days on KAYAK

Save 23% or moreCompare multiple travel sites with one search.

Track pricesNot ready to book? Create a price alert for when prices drop.

Bundle and saveSave money when you bundle your flight + hotel.

Filter your dealsChoose cabin class, free Wi-Fi and more.

Flight Deals
Booking Insights
Flight Deals

Cheap Flights from Denver to Illinois

Cheapest round-trip prices found by our users on KAYAK in the last 72 hours
Chicago
Chicagononstop$114
Moline
Molinenonstop$209
Peoria
Peoria1 stop$219
Bloomington
Bloomington1 stop$339
Champaign
Champaign1 stop$460
Springfield
Springfield1 stop$465
St. Louis
St. Louisnonstop$79
Decatur
Decatur1 stop$373
Chicago
Chicagononstop$114
Moline
Molinenonstop$209
Peoria
Peoria1 stop$219
Bloomington
Bloomington1 stop$339
Champaign
Champaign1 stop$460
Springfield
Springfield1 stop$465
St. Louis
St. Louisnonstop$79
Decatur
Decatur1 stop$373

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

Fri, Feb 20 - Mon, Feb 23
Frontier Logo
10:01 am - 1:09 pm
DEN
-
STL
2h 08mnonstop
Frontier Logo
1:54 pm - 3:30 pm
STL
-
DEN
2h 36mnonstop
$79Frontier
Fri, Feb 20 - Mon, Feb 23
Frontier Logo
10:01 am - 1:09 pm
DEN
-
STL
2h 08mnonstop
Frontier Logo
1:54 pm - 3:30 pm
STL
-
DEN
2h 36mnonstop
$80Frontier
Fri, Apr 17 - Sat, Apr 25
United Airlines Logo
6:10 pm - 9:32 pm
DEN
-
MLI
2h 22mnonstop
United Airlines Logo
8:54 am - 10:33 am
MLI
-
DEN
2h 39mnonstop
$209United Airlines
Fri, Apr 17 - Sat, Apr 25
United Airlines Logo
6:00 am - 12:36 pm
DEN
-
PIA
5h 36m
1 stop
United Airlines Logo
8:50 am - 10:33 am
PIA
-
DEN
2h 43mnonstop
$219United Airlines
Thu, Feb 19 - Mon, Feb 23
American Airlines Logo
5:57 pm - 11:25 pm
DEN
-
PIA
4h 28m
1 stop
American Airlines Logo
5:23 pm - 10:40 pm
PIA
-
DEN
6h 17m
1 stop
$229American Airlines
Thu, Feb 19 - Sun, Feb 22
American Airlines Logo
2:49 pm - 10:53 pm
DEN
-
MLI
7h 04m
1 stop
American Airlines Logo
1:36 pm - 5:17 pm
MLI
-
DEN
4h 41m
1 stop
$229American Airlines
Thu, Feb 19 - Sat, Feb 21
Delta Logo
1:10 pm - 10:24 pm
DEN
-
MLI
8h 14m
1 stop
Delta Logo
5:01 pm - 12:23 am
MLI
-
DEN
8h 22m
1 stop
$249Delta
Thu, Feb 26 - Mon, Mar 2
Multiple Airlines Logo
7:24 pm - 7:06 pm
DEN
-
EVV
22h 42m
1 stop
Multiple Airlines Logo
7:46 pm - 6:17 pm
EVV
-
DEN
23h 31m
1 stop
$326Multiple Airlines
Tue, May 5 - Tue, May 12
Delta Logo
6:00 am - 3:38 pm
DEN
-
BMI
8h 38m
1 stop
Delta Logo
4:00 pm - 11:51 pm
BMI
-
DEN
8h 51m
1 stop
$339Delta
Wed, Feb 11 - Sun, Feb 15
Multiple Airlines Logo
2:19 pm - 8:37 am
DEN
-
RFD
17h 18m
2 stops
Multiple Airlines Logo
12:41 pm - 12:58 pm
RFD
-
DEN
25h 17m
1 stop
$370Multiple Airlines
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 Chicago, at $114 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 $114.

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 $279, 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 $195 (return) on average. On the other hand, the most expensive months are November and October, when the average cost of round-trip tickets is $257 and $229 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 Thursdays and avoid leaving on a Sunday, as it's usually the priciest day. When flying back from Illinois, Saturday 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 42% 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$40
Best time to beat the crowds with an average 10% drop in price.
Most popular time to fly and prices are also 4% 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 Southwest
DEN
-
ORD
Oct 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 Airlines
DEN
-
ORD
Jan 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 $200 on average. On average, there is no price difference when choosing to fly in the morning or the evening on this flight route. 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 $586.

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 - $227 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 4267 reviews
8.0Comfort
8.6Crew
7.0Food
8.1Boarding
7.5Entertainment
Airline reviews

All good except once again bags took an hour at Midway Airport Happens all the time. Ridiculous

10.0 ExcellentAnonymous, Jan 2026
PHX - MDW
Read more Southwest reviews

All good except once again bags took an hour at Midway Airport Happens all the time. Ridiculous

Everything went smoothly and we even arrived a little bit early.

Great vacation. Can't wait till next year for another one.

The seats were comfortable, and the boarding process was pretty smooth.

It was rough. The staff was unprofessional, the choice of on board drinks terrible, it was cramped in space at every airport, they always ran out of overhead bin space so they pressured people to check bags for free or we couldn’t leave on the plane— so I did check my bag to help, and they nearly lost my bag. My bag did not arrive on the luggage belt, another man on my flight and I had to waste our time going to the baggage office to search for our bags. I would only fly southwest again if it was my last choice. Also, my flights were consistently delayed over and over again— at one point they straight up told us we were waiting for the pilot to arrive.

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.

Sitting on the runway after we land for almost two hours! Not sure if we should blame United or Just Dumpy Vance.

Flight was late - I was downgraded from first class to coach

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

Pilot navigated severe weather/snow storm with skill. Described his intentions clearly

Little warm on the plane and delayed for an hour

So excited very proud first of all I wanna thank kayak all updates very professional and fast alart And amazing cabin crew so nice to me they deserve big salute

The boarding process needs to be fixed. The zone don't work, especially when there is hardly anyone in zones 3, 4,and 5, leaving the majority of the passengers backed up in the aisle, especially because passengers seated near the front are blocking passengers who are seated in the rear of the plane. It would also help if the size of carry on bags was more strictly enforced.

Awful. They won’t help me with anything. I booked on American but they abdicated to Iberia. The ticket was overpriced. Everything negative

I enjoyed the extra leg room compared to other airlines. The first stewards made my daughter’s birthday special by giving her an extra snack. Then the last one coming home from Chicago to Appleton made our night really enjoyable Thanks for making our trip enjoyable

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.

It was fine. Nobody was outstandingly friendly but no one was rude and everything was smooth . The captain thanked us for flying but no one greeted me as I walked on the plane or as I exited which is the least they could do lol

Clean, friendly, roomy. But check-in from the phone link was terrible. Repeated attempts wouldn’t save at the final step. Just kept spinning! It was very frustrating. Finally, I used the app (vs website link) to check-in which worked very smoothly on the first attempt.

Check in on the web portal was cumbersome! After several attempts I finally got the boarding pass.

Excellent flight and even arrived 23 min early. No entertainment , or wi fi on board, but I downloaded a couple of movies beforehand which kept me entertained. Really like flying Allegiant airlines.

WE were delayed about an hour and never any communications from the employees working the gate. We also were moved to a total of three gates.

I love how they show love to their customers and care about them too.

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.

Good for a budget airline! It was easy to get on, staff was really nice. Can’t say anything about the food or entertainment because it wasn’t available, which is fine.

This company socks. It's fraud. They canceled our flight yesterday, and today we were late because of a really long line at the check in bag. At the rebook station, there was ton of people. The workers were all rude. I am gonna make a report to FTC.

Not clean and was told I would get a great seat and it was not great at all

Delayed. Text notifications were slow. Not much information o what was happening. Boarding was slow and confusing. Wasn’t even offered water other flight. Had to ask. No entertainment at all. Felt like.a Greyhound bus.

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!

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

Information on your arrival and departure airports