$92 Find Cheap Flights from Illinois to Colorado - Compare and Save

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Low season

April

Cheapest flight

$92
Best time to beat the crowds with an average 15% drop in price.
Most popular time to fly with an average 12% increase in price.
Flight from Chicago O'Hare Airport 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 (235 flights per week), Air Canada (164 flights per week), and American Airlines (70 flights per week).

  • How many airports are there in Colorado?

    There are 13 airports in Colorado. The busiest airport is Denver Airport (DEN), with 89% 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 $225.

  • What is the cheapest day to fly to Colorado?

    Based on KAYAK data, the cheapest day to fly to Colorado is Friday where round-trip tickets can be as cheap as $282. On the other hand, the most expensive day to fly is Monday, where round-trip prices are $377 on average.

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

    The cheapest time of day to fly to Colorado is generally at night, when round-trip flights cost $248 on average. Morning departures are around 10% cheaper than evening flights, on average. The most expensive time of day to fly to Colorado is generally in the evening, which is peak travel time and where the average cost of a ticket is $346.

  • What is the cheapest flight to Colorado?

    The cheapest ticket to Colorado from Illinois found in the last 5 days was to Denver, at $159 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 5 days was $159.

  • 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 $165 (return) on average. On the other hand, the most expensive months are August and July, when the average cost of round-trip tickets is $226 and $215 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 39% 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 877 direct flights each week.

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

    There are around 129 direct flights from within Illinois to Colorado every day. Most flights (33%) depart in the morning.

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

    Each week there are around 899 direct flights from within Illinois to Colorado. The most common day for departures is Sunday, with 16% of flights taking off on this day.

  • How long is the flight to Colorado?

    An average nonstop flight from Illinois to Colorado takes 5h 52m, covering a distance of 925 miles. The shortest route is St. Louis (STL) to Denver (DEN) with an average flight time of 2h 20m.

  • 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 899 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 (92% of total searches to Colorado). The next most popular destinations are Colorado Springs (5%) and Vail (2%). Searches for flights to Grand Junction (1%) 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 4196 reviews
8.6Crew
8.0Comfort
7.0Food
8.1Boarding
7.5Entertainment
Airline reviews

The Southwest airline was ok. A big thank you to Kayak team (David), who worked with me on Sunday afternoon to rebook my travel from Burbank, CA, to CVG. My original flight on Sunday was delayed, so I had to cancel Sunday flight and rebook my travel to Monday. Could not have done it without help from David from Kayak team. Ante Soda GE Aerospace

10.0 ExcellentAnte, Aug 2026
Read more Southwest reviews

The Southwest airline was ok. A big thank you to Kayak team (David), who worked with me on Sunday afternoon to rebook my travel from Burbank, CA, to CVG. My original flight on Sunday was delayed, so I had to cancel Sunday flight and rebook my travel to Monday. Could not have done it without help from David from Kayak team. Ante Soda GE Aerospace

Flight time kept changing and so did the gate. It was very frustrating

Friendly crew kept coming by to make sure all was ok, provide additional refreshments, etc.

Flight was delayed by 2 hours, meaning that a flight to Dwnver which should have arrived at 11pm came into the airport at 1 am. Made for a very long day.

Crew was rude, flight was late, wifi didn't work, no food, basically nothing about this flight was good.

Flight was constantly delayed with significant changes in time, it was supposed to get to Colorado Springs at 8:30 PM but it got there after midnight.

Airline is not very senior friendly. Flights are late, forcing us to run to the connecting flight. Food is awful. Wish they would go back to pretzels and peanuts. During flight, pressurization isn’t quite right and all of our ears get plugged. Everything is nickel and dime, charging for boarding, seat selection and legroom. While a screen at the desk in the gate area says check your roll on bag now for free due to space limitation, the employee at the desk will not check the bag without a $100 fee. Insane.

We waited in the airplane for over 45 min for a southwest employee to make the flight. This cause over half the plane to miss their connecting flight in Denver. When we confronted the desk upon arrival, they told us the only flight they had was the next day leaving at 8:50 pm!!! Or they offered to get us to Burbank or LA, but after that we were on our own to get back to Santa Barbara. I paid for a flight from sba to bna bna to sba. My re entry into mom mode has been 💯 rough because of southwest mistake with my flight. And now I’m leaving to Reno tomorrow for a vballl tournament and just discovered that my leg in Vegas has me and my 3 kids on a stand by flight even though I had booked these ticket last year November!! Do better southwest!

One of the crew performed a hilarious skit to accompany the standard instructions. Passengers enjoyed it so much they applauded at the end!

Long delay due to mechanical issues. They should have just swapped the plane and not make us wait while they figure it out. Disappointed

Smooth flight, easy boarding process. Made up time in the air with initial delay due to weather pass through

awesome team work seen since on board till off plane in my destination. thanks you so much.

They did not have free WIFI and I was not okay with that!

Great, except the canon was so cold. Even the flight attendants put jackets on

I missed the flight due to maintenance issues. This is the second flight I’ve missed in four days because United allows such little time between layovers. Very disappointing

It was serviceable, nothing special but nothing awful on this leg.

The back to back mechanical delays from Denver to San Diego and then on my return flight from Denver to Great Falls it added extra time both ways

Excellent flight. Boarding was efficient and departure was on time. Smooth flight with on time arrival. Deplaning was also efficient.

late departure due to some unspecified issue with ventilating the cabin. They got it running but it was FREEZING for the whole flight. I asked for a blanket but they didn't provide one. They could not turn up the heat. it was quite miserable.

Plane was so old it had cigarette butt trays in the seat

The flights to and from Cincinnati were great at being on time for both, departures and arrivals. The planes could use some updating.

It was a dismal experience. The flight was delayed for 4 hours, and we spent hours in the plane, without air, during the summer. We were not provided with water, and the medical assistance was inadequate when it arose.

The landing the pilot was very smooth. The flight attendant was kind of rude.The boarding the plane in punta Gorda was not great made us wait out in the heat 😞

My exit seat was very comfortable Coffee was to be purchased but sodas free 😏

It was poor a four hour delay and no explanation for the delay. What’s a 35 dollars going to do. It also made me miss my car rental,

It was on time. Flight was comfortable. Staff was nice. It was the way a flight should always be.

The price was the only good thing about this flight. It was scary during takeoff when the plane tilted side to side. It made me feel very nervous as I have never had a take-off that unsmooth. There was no on-flight movie or music options and the only complimentary option was water. Other airlines offer trail mix or a caramel cookie and pop options as complimentary. This flight was a 2.5 hour flight. I understand for shorter flights not having options, but a flight 2 hours or longer should offer more complimentary options and in flight entertainment. Also the seats did not recline and for a longer flight reclining seats are a must for comfort.

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.

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.

I went to lower my tray table and it was very nasty. Looks like some one had left some food on it and then just closed it up.

Everything was delayed and the staff sent me to the wrong gate, causing me to miss one of my flights. I arrived at my destination 6 hours later than I was supposed to.

On the return flight, arriving in Denver we sat on the tarmac in Denver for over 20 minutes.

The flight was fine. It's the satellite terminal that supports American eagle flights is what sucks. There is only one food option and everything there is way overpriced. I mean I know it's airport pricing, but it's even crazier than that. I bought a sandwich in a plastic container for $18.

Don't change gate multiple times make people run across the airport. Announce delays in a timely manner. Have maintenance crew ready. Don't delay and keep passengers on the plane for 3 hrs. on tarmac.

My seat tv didn’t work the whole trip. And the seat space is too small despite being seated at the front.

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

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.

Because I can’t stand very long in one place, I was allowed to reword.

I know Frontier is a “no-frills” airline. I understand the concept. However, I jumped on some tickets for our family vacation, expecting to play a bit of a game to figure out the family bags and not over spend. In the end, I got the short end of this deal by far. 1. I did not expect them to charge the baggage fee for each direction. It makes the fee look high-ish at a glance, but reasonable. Then when you get to checkout and realize you have to pay it twice to come home with your luggage, it becomes ridiculous. 2. The low checked bag weight limit. I am used to packing a 50lb bag with my preferred airline. Frontier’s artificially low 40lb limit more quickly triggers the extra weight fee, which almost DOUBLES the price of the bag if you go over ($79 for the bag/$75 for the next 10 lbs) 3. The fee for a carry-on bag is the same as a checked bag but with a lower size and weight limit. Make it make sense! 4. The seats are terrible. My 2.5 hour flight almost had me losing my mind. I’m 6’3” and my femurs barely fit in the space provided. My knees had to wiggle just right to jam into the crack next to the armrest of the seat in front of me. The cushioning was thin and inadequate. I am tall but I’m not a freak. These seats are unacceptable. 5. I overheard the woman next to me speaking with the gate agent about being charged a $25 fee for not checking in online - she checked in at the airport counter when she arrived. That’s ridiculous. She was old and in a wheelchair. She had a paper boarding pass, and was obviously not tech savvy. She should not be punished for that. 6. They do not have good placement in the terminals. It was always out on the end or down on a subfloor, and we had to walk out on the tarmac almost every time. In Denver. Their home airport! 7. Every time I loaded a new page on the website while buying my tickets or my bags, it was constantly trying to upsell me on some esoteric bundle. Like, a pop-up every time. Very annoying. 8. No screens in the boarding area (at least where we were) to confirm you’re in the right place. Just static gate number signs. I am sure these are standard practices for Frontier, and I should have read more about them before I purchased tickets, but as a result of this single round trip, I do not plan to ever use this cut-rate airline again. I would rather pay the normal amount for a ticket and be treated like a customer instead of a mark.

Great except upon arrival it took them a long time to open the doors

It was awful ....my first time flying on it and I will NEVER fly it again ....everything about it was terrible .....most especially the flight attendants

There weren't enough employees at check in took awhile to get bags checked. There wasn't a wheel chair for me, I was sent to someone who turns out to work for a different airline, if My flight hadn't been delayed I probably would have missed my flight as it was, by the time I arrived at my gate, they started boarding in about 15 minutes. I don't know who took me to my gate, definitely was not the normal people who take passengers to the gate. I'm guessing she may have been in a management position. I wish I knew her name, she went beyond to help me. With that said everyone was kind, and were doing the best they could. So, I choose to say it was an Adventure, stressful start, but good. In the end went well. The situation was not only difficult for passengers but the employee's.

Frontier scheduled a 40 minute connection in DEN. What they failed to mention was that they “close the doors” 20 mins prior to departure, which means you only have 20 mins. Not enough time. Possibly against DOT regulations. Filing complaint.

It was an early flight and most people napped/slept and the crew let us which was nice.

More inflight connection. And leg space is horrible. And the paying for baggage I'd ridiculous!!!

It was costly and difficult to check in. $85 to take a small suitcase with me, carry on or checked and $75 on the return trip, Plus $25 if I didn't check my self in check in $25, because I couldn't do it on the kiosk. Small very uncomfortable seats, waited on the runway for near an hour each way. It was my worst flight to date.

Our flight was canceled for no known reason. We weren’t told until we were checking in at 5:00 am. This was after our last flight with Frontier where we sat on the plane for three hours (not an exaggeration) before we took off because of a mechanical issue. We won’t be flying Frontier again.

I didn’t have enough time to catch my connecting flight and had to use a different Airline. I will be requesting a refund.

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