$78 Find Cheap Flights from Illinois to Colorado

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Illinois to Colorado departing on 8/19. 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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1 adult, Economy, 0 bags

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Low seasonApril
Cheapest flight$78
Best time to beat the crowds with an average 10% drop in price.
Most popular time to fly with an average 10% 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 (164 flights per week), Air Canada (99 flights per week), and Southwest (60 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 $216.

  • 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 $253. On the other hand, the most expensive day to fly is Monday, where round-trip prices are $325 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 $237 on average. Morning departures are around 14% 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 $307.

  • What is the cheapest flight to Colorado?

    The cheapest ticket to Colorado from Illinois found in the last 5 days was to Denver, at $158 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 $158.

  • 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 $172 (return) on average. On the other hand, the most expensive months are April and February, when the average cost of round-trip tickets is $339 and $318 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 36% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 9 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 595 direct flights each week.

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

    There are around 89 direct flights from within Illinois to Colorado every day. Most flights (35%) depart in the morning.

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

    Each week there are around 620 direct flights from within Illinois to Colorado. The most common day for departures is Sunday, with 15% of flights taking off on this day.

  • How long is the flight to Colorado?

    An average nonstop flight from Illinois to Colorado takes 6h 00m, covering a distance of 926 miles. The shortest route is St. Louis (STL) to Denver (DEN) with an average flight time of 2h 15m.

  • 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 620 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 (84% of total searches to Colorado). The next most popular destinations are Colorado Springs (7%) and Aspen (3%). Searches for flights to Montrose (2%), to Durango (1%) and 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.
7.9
SouthwestOverall score based on 4237 reviews
7.0Food
8.1Boarding
8.6Crew
8.0Comfort
7.5Entertainment
Airline reviews

there were two flight attendants that were up front...that were the best! They get KUDOs for making my trip only fantastic. Tell them Jeff said that!

10.0 ExcellentAnonymous, Jun 2026
OKC - LAS
Read more Southwest reviews

there were two flight attendants that were up front...that were the best! They get KUDOs for making my trip only fantastic. Tell them Jeff said that!

OKay. I sat in the back of the plane and it was really loud between babies and little kids, and adults who.like to talk a lot and loudly most of the flight.

Flight coming out of Buffalo was delayed, so we had to be rescheduled on another flight from Baltimore to Phoenix which means we had a long layover and got home 3.5 hours late. Shuttle to parking stopped at 10pm, so we had to pay for an Uber to the parking lot and got charged an extra day of parking since it was after midnight. Not the best experience. Long day!

Was fine, delayed and feels like southwest is always late

I don't know why flying out of Sarasota requires two plane changes.

The first time I flew in the extra legroom section. It was difficult to notice a difference. I had bad luck with my neighbors. The crew was okay. Southwest has reduced the live TV options.

The flight was smooth. The Southwest experience has degraded overall, but this one was okay.

No gluten free snacks. Seats felt worn or bare bones even though it was a new 737 MAX 8.

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!

I flew twice this week on Southwest, was delayed over 2 hours both ways. From Pittsburgh to Chicago it was due to weather but the gate agents, pilot etc were great at updating everyone. Today from Midway to Pittsburgh the plane had come from an international location, kept getting delayed, no information was given until we were delayed for the third time. It was ridiculous, whoever scheduled that plane to fly to Pittsburgh after didn’t consider a lot of things.

Read the fine print. This was my flight home. I booked my flight for the quickest way home. Had a carry-on and a personal item. Same as my outbound flight. Apparently I needed to pre-pay extra for my carry-on. When I checked in, I was told that I had to check it. I said I’ll pay for it, and was told that this wasn’t an option anymore. They said I still had to pay $50 to check my carry-on. I told them I’ll pay whatever to just carry it in as intended. I was not allowed, so eventually I paid $50 to check my carry-on under a plane that was half full, with overhead compartments that were even less full. My white carry-on suitcase was practically destroyed getting from Idaho falls to Denver to Orange County. The low price air fair was a bait and switch. Got me to the gate, made me pay extra, then didn’t even allow me to pay for a carry on. Not to mention that I paid the $8 for WiFi that didn’t work. All to get my suitcase destroyed. I don’t think I’m going to even keep my Untied mileage plus membership and card. Apparently, membership does not have its privileges for this one.

I flew from Santa Fe to Denver to catch a flight to London and the transfer of my luggage on arrival at Denver to the London flight worked perfectly. The crew on the ground and on board for the London flight were so friendly and efficient.

It was a short flight so I was expecting too much

Late- that’s what United does best. Missed my connection, rebooked to a flight 17 hours later and had to spend $500 on a hotel. What did I get? A $15 meal voucher. What can you get in an airport for $15. I hate United so much.

It was good overall except from Omaha to Denver when flight a was a repeatedly delayed apparently due to some issue at Denver. Communications could have been handled better. I had to board then deboard with luggage and board again

Booked through Kayak Business, had a seat in middle and towards back due to booking rate, not comfortable.

They told us yesterday APR21st that they were cleaning the plane and we got delayed. After that they said they didn't had any crew for the flight so they cancelled the flight till next day.

The flight crew on this leg of my trip was very friendly and pleasant. Every one of them was humorous, as well as helpful and accommodating. This group was BY FAR the best crew I’ve flown with. They deserve kudos.

The entertainment options on the seat back video boards were nice.

The boarding process was straightforward. One pertinent observation regarding all boarding procedures is that if an individual requires assistance or possesses a special status and is part of preboarding, it is advisable to limit the number of passengers who can preboard with them, rather than the entire, sometimes large, companion groups. The seats are uncomfortable, and the entertainment options are significantly inferior compared to other airlines. During the snack service, I requested an additional bag of snacks, but my request was denied. Initially, the flight attendant agreed to my request.becoming a strange accurate moment. The flight duration was four hours.

Seats were very uncomfortable and being charged for snacks and water.........

Allegiant actually impressed me, original inbound flight from PBG was so late they gave us a bird inbound from Des Moines and only left 1h late and gained 40 minutes back in the air. Comfortable flight with no frills but no complaints.

Flight was delayed. Crew was good but hot coffee was not available.

Great. No choice for n/a. No food or entertainment options

No food is available without purchasing it and there is no in-flight entertainment. Both of these are OK because we got an inexpensive flight from Allegiant and, otherwise, our experience was excellent.

just had water and there was plenty of leg & seat room. But then i don't weight 220#s!!

Not totally their fault- screaming kids that had zero parent intervention.

It was cold on the flight. The crew was very pleasant. I didn't order any food. We were delayed due to Captain waiting on maintenance log. He kept us informed though. The flight itself was smooth. I would definitely fly with Allegiant again!

I had a fantastic experience with Allegiant. I had wheelchair assistance and they helped me find my luggage and brought me to my car. Even loaded my luggage. Wonderful service!! Thank you Allegiant!

Superb. Staff great. Great flight. As with other airlines, seating too tight and restrictive.

It wa sort of on time; the cab was left with some trash

American Airlines II: Delay Boogaloo. Multiple gate changes, delays, boarded and then MORE delays. I hate to say this won’t matter, but posting stuff about major corporations in 2026 is a post-modern “scream into the void.” Was multiple hours late coming home, so there you go.

The airplane was an old model, the overhead didn’t have enough room for people’s items and made boarding and boarding disappointing and stressful. Crew allowed passengers to bring more than the permitted baggage sizes.

Original flight was on time, then late, then changed gates...4 times. Once our newest plane came in, it was fine.

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.

I almost missed my flight and they helped me out enormously

Delays experienced in boarding/take off due to incoming plane delayed. However, the boarding time/depart time in the app was significantly delayed in providing these updates. Usually not updated until an hour after we should have already boarded. Poorly managed.

Moved to earlier flight which unexpectedly had maintenance issues initially indicated as quick fix to ultimately plane changes. Moved back to original flight, also delayed. In all cases customer updates and communication very unclear, no updates on drivers for delays.

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

Typical AA - late by 90+ mn. Gate changed twice... Changed the departure time 6 times No explanation, no communication on reasons for delay I travel with AA twice a year... and it is consistently very poor.. I will continue to use AA only when i have to.

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!!!

Flight was canceled. Most upsetting was message from Kayak, stating that the flight was canceled and click with Kayak for details regarding rebook, refund details. THERE'S NO INFORMATION PROVIDED BY KAYAK EXCEPT THAT FLIGHT IS CANCELED. AND NOW THIS SURVEY TO FIND OUT HOW WAS THE FLIGHT !!!!!!!

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.

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.

Better than expected. Staff were friendly and nice on both flights.

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!!!

Just know that everything, and I mean everything is “ala cart”. 60$ just to put something in the overhead bin. I will never fly Frontier again nor do I recommend them to anyone else.

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.