$28 Find Cheap Flights from Illinois to Colorado

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Low seasonJanuary
Cheapest flight$28
Best time to beat the crowds with an average 15% drop in price.
Most popular time to fly with an average 7% increase in price.
Flight from St. Louis to Denver

FAQs for booking flights from Illinois to Colorado

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

    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 Illinois to Colorado.

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

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight from Illinois to Colorado 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 Illinois to Colorado?

    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 Illinois to Colorado 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 Illinois to Colorado?

    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 Illinois to Colorado up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

  • Which airlines fly most frequently to Colorado?

    Illinois and Colorado are connected by different airlines. The airlines that fly that route the most regularly are United Airlines (198 flights per week), Air Canada (97 flights per week), and American Airlines (82 flights per week).

  • How many airports are there in Colorado?

    There are 13 airports in Colorado. The busiest airport is Denver Airport (DEN), with 84% of all flights arriving there.

  • Which is the cheapest airport to fly into in Colorado?

    Prices will differ depending on the departure airport, but generally, the cheapest airport to fly to in Colorado is Denver Intl Airport (DEN), with an average flight price of $257.

  • What is the cheapest day to fly to Colorado?

    Based on KAYAK data, the cheapest day to fly to Colorado is Saturday where round-trip tickets can be as cheap as $235. On the other hand, the most expensive day to fly is Sunday, where round-trip prices are $279 on average.

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

    The cheapest time of day to fly to Colorado is generally in the morning, when round-trip flights cost $243 on average. Morning departures are around 12% cheaper than evening flights, on average. The most expensive time of day to fly to Colorado is generally in the afternoon, which is peak travel time and where the average cost of a ticket is $299.

  • What is the cheapest flight to Colorado?

    The cheapest ticket to Colorado from Illinois found in the last 72 hours was to Denver, at $122 round-trip. The most popular route is Chicago Midway Airport (MDW) to Denver (DEN) and the cheapest round-trip airline ticket found on this route in the last 72 hours was $122.

  • What is the cheapest month to fly from Illinois to Colorado?

    The cheapest month for flights from Illinois to Colorado is October, when tickets cost $173 (return) on average. On the other hand, the most expensive months are December and November, when the average cost of round-trip tickets is $242 and $241 respectively.

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

    To get a below average price on the flight from Illinois to Colorado, you should book around 4 weeks before departure, which saves you about 35% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 5 weeks before departure.

  • How many cities have direct flights to Colorado?

    From Illinois, there are direct flights to Colorado from 3 cities. The city with the most direct flights is Chicago, with 656 direct flights each week.

  • How many direct flights to Colorado are there each day?

    There are around 98 direct flights from within Illinois to Colorado every day. Most flights (41%) depart in the morning.

  • How many direct flights to Colorado are there each week?

    Each week there are around 682 direct flights from within Illinois to Colorado. The most common day for departures is Sunday, with 20% of flights taking off on this day.

  • How long is the flight to Colorado?

    An average nonstop flight from Illinois to Colorado takes 6h 25m, covering a distance of 931 miles. The shortest route is Peoria (PIA) to Denver (DEN) with an average flight time of 2h 05m.

  • How many long-haul flights are there to Colorado each week?

    There are not any long-haul (6-12 hour flight duration) or medium-haul (3-6 hour flight duration) flights to Colorado. Instead, there are 682 short-haul flights (up to 3 hour flight duration), with the most arriving from Chicago.

  • What are the most popular destinations in Colorado?

    Based on KAYAK flight searches, the most popular destination is Denver (81% of total searches to Colorado). The next most popular destinations are Colorado Springs (5%) and Vail (4%). Searches for flights to Hayden (3%), to Aspen (3%) and to Montrose (2%) are also popular.

Reviews of the top 5 airlines serving from Illinois to Colorado

 
Need help choosing which airline to fly with from Illinois to Colorado? 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 4249 reviews
8.6Crew
8.0Comfort
7.5Entertainment
8.1Boarding
7.0Food
Airline reviews

The flight crew was extremely rude and especially not helpful when our flight was delayed.

2.0 MediocreMatthew, Jan 2026
DAL - SAN
Read more Southwest reviews

The flight crew was extremely rude and especially not helpful when our flight was delayed.

Pretty seamless, just a tad bit late in taking off and landing.

Plane crashed into a bus or some other vehicle on the ground while pulling out of the gate. No injuries, but wing tip was damaged and returned to gate for “maintenance issues” and we departed 5 hours later because the plane went out of service and new plane was flown in from a nearby airport, Midway.

All was good. I just had a hard time getting connected to the WiFi/internet during the flight

Sacrament staff are always polite and helpful. Airport is easy to maneuver and boarding is straightforward.

Near 4 hour flight with only 1 service. Had to use call button to request water. Internet and power not working until into flight. Internet would stop working during flight.

Better and more food and drinks. Put msnbc and free speech tv on the news channel selection list.

The Southwest employees (all two of them) were very nice and cheerful despite the fact the line to self-check a bag (simply drop it off) was hundreds of people long. Thank God I arrived early to the airport because I stood in this line for at least an hour. Once on the flight that had been delayed by an hour, we had no Wi-Fi and thus no entertainment. Finally, I hope the investor strong arm tactics against Southwest pay off in a short-term windfall to your C-Suite because the rest of you are screwed. I have been a faithful Southwest customer for 15 years due to everything you just got rid of. I'm flying to Idaho and Washington in October, both places I used to simply book with Southwest without a second thought now with Frontier (Washington) and United (Idaho) because they offer everything the "new" Southwest does but cheaper and at better times, destinations, etc. This really makes me sad...

after landing, we stay 2 hours on the taxi way before reaching the gate The airline and the crew were good though

Flights delayed by 4-6 hours. Boarding was a mess and unclear. Bags were not at arrival airport and had never even been put on the plane. No idea when I’ll get them. Don’t fly into Denver!

The flight was delayed by two de-icings. The seatbelt did not work correctly. It did not stay tight.

Hotter than Hades in August. Why, why do crews think that in the winter when we are already dressed for cold weather we need a cabin that is 82 degrees. Even the vents were blowing hot air.

Flight was delayed. De-icing took a while. When we landed had to wait for another plane to vacate our gate. Just an overall bad experience.

Not good - outbound flight was delayed and missed my connection even though I got to the gate after running through the airport - the agent would not let me on because the door was closed (flight had not left). There was no notification from United - overall experience was very disappointing. Additionally, I was downgraded from first class to coach on the alternative flight

United have really come back. Airport and boarding process is clear and good, app and information also very good

The entertainment available didn’t work for anyone on the flight. Long 6 hr flight with no entertainment option and the staff didn’t know until an hour into the flight when we made sure they knew about it. They had no way to fix it.

Late FA meant slow boarding. WiFi did not work. I’m a medium plus sized passenger. The seatbelt was for the first time ever barely fitting. And we delayed on the tarmac 40 min

My husband and I had boarded the flight from Denver to Chicago, and one of the last passengers to get on the plane opened the overhead bin above my husband's seat and threw his bag out of the bin to make space for his own. He said, "Mine is bigger!" The flight attendant supported the new passenger. They didn't care that my husband has two artificial knees and must have the foot room in front of his seat to be able to fit his legs in -- and to be able to stand, much less walk, at the end of the flight. I have never seen this happen before, and it was a disaster.

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

I understand stuff happens, but plane failures are likely due to lack of maintenance. Additionally, air conditioning wasn't working, no snack/drink service, no WiFi. Fortunately, the crew was communicative and light-hearted. United grabbed another plane and we were able to get to our destination.

Kayak was among the missing. There was not the usual advice regarding next gate after arriving in Dallas. No communication after the reminder to check in before the Moline flight. What happened?

Crew were all friendly and helpful. It was a short flight so just a beverage service with a cookie. After we were boarded the plane took about 45 minutes to leave the gate but it was New Year’s Eve so not shocking there was some delay. Overall good experience and very grateful.

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.

The boarding by groups is pointless. The first two groups worked fine, but almost Noone boarded in goups three thru five leaving the vast majority boarding when group six was called. It defeated the purpose of spreading out the crowd.

We loved the steward on the plane. He made the night enjoyable

Flight was delayed leaving Dallas. Arrived about 2 hours later than scheduled.

The plane was late, when we did board the plane was as cold as a freezer. I was freezing the entire flight, no blankets. Lost miserable flight I’ve ever had.

We were delayed for a “couple of maintenance issues.” They were resolved rather quickly but a computer glitch caused someone in the airport to have to bring a physical copy of the paperwork so we could leave. I don’t know where they had to drive from to get to our plane but it took forever & we were 1 1/2 hrs late in leaving. The flight itself was fine.

Because the plane was 90 degrees F, they would not let us board. I wish they had, because it meant we were delayed. It's Texas, of course it's hot. We would have survived.

Our bags took a long time to get unloaded once we landed.

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.

Due to weather, my flight was delayed, further delayed, then canceled. I eventually got through to a support person who helped me find a different route out of MSP, but to get to DIA, they didn't want to, but eventually did help with the connection ticket purchase. But even this replacement flight was delayed time and time again, and I would have missed my connecting flights and I didn't want to get stuck in a layover city, so after 12 hours at the airport with two young boys who were very tired, we just cancelled our plans and spent the week at home, instead of Nana's.

I knew going into this that Frontier, being a low cost carrier, would be pretty bare bones and charge for most extras but this was made up for by the fact that the airplane was a reasonably new Airbus, every employee was great and best of all, Everett Washington is an amazing airport - thanks Frontier for flying there!!!

Seats were new and comfortable. Staff was fine. Missed my connection due to weather -which wasn’t their fault- but got no help at all. Gate staff sent me to customer service, which was and stayed unstaffed. Sign with QR code directed me to call or chat. Chat was useless. Call was returned after an hour. No itinerary offered by Frontier could get me home in less than 30 hours. Rebooked with another airline and got a partial refund that came to about 10 percent of what I paid to get home.

The experience was good. No frills but I got there safe and sound and on time.

As every law enforcement agency I could imagine surrounded the plane and we didn’t disembark for 2 hours and then had to stick around for another hour to go get our personal belongings after leaving them behind and being bused away from the plane, it was scary and inconvenient. We were given no information as to why this was happening. Lack of communication with passengers was disappointing.

Frontier Airlines was AWFUL. I was an hour early for my flight and the lady refused to check me in. I had to purchase a whole new ticket with a different airline.

Late, terrible communication, horrible planning of passenger seating until the literal last minute. One of the worst flying experiences of my life. Y'all suck

First of all, we never got on the connecting flight to Denver. They delayed our flight for two hours. If we would have gotten on that flight, we would have been stuck in Denver for 13 hours. So we re- routed our flight for a straight through flight to Oklahoma two days later. THEN, they delayed that flight for two hours. After that we were able to finally get on our flight and come home. Frontier Airlines - one of the worst airlines I have ever been on.

Terrible communication with weather delay, lost baggage, near impossible to reach customer service

My tickets got canceled on me by your site and I didn't have a flight. Then you kept sending me emails on the status of q flight I didn't have tickets for.

Everything you need to know for your flight to Colorado

Cabin class types available on flights to Illinois

Cabin classes available on flights to Illinois. Prices are the lowest found on KAYAK over the last 7 days. Price and availability is not guaranteed.