$103 Find Cheap Flights from Colorado to Illinois - Compare and Save

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Colorado to Illinois departing on 8/4. 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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Low seasonJanuary
Cheapest flight$103
Best time to beat the crowds with an average 3% drop in price.
Flight from Denver to Chicago O'Hare Airport

Flights from Colorado to Illinois: the best tips from KAYAK users

Insights shared by verified travelers who flew the route from Colorado to Illinois 
JoanneFlew with United Airlines
DEN
-
ORD
Jun 2026
The runway to gate took a bit of time. So if you have a short layover pay for a seat up front .
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 for booking flights from Colorado to Illinois

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

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

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

    Colorado and Illinois are connected by different airlines. The airlines that fly that route the most regularly are United Airlines (167 flights per week), Air Canada (113 flights per week), and Southwest (58 flights per week).

  • How many airports are there in Illinois?

    There are 12 airports in Illinois. The busiest airport is Chicago O'Hare Airport (ORD), with 91% of all flights arriving there.

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

    Prices will differ depending on the departure airport, but generally, the cheapest airport to fly to in Illinois is Greater Peoria Airport (PIA), with an average flight price of $152.

  • What is the cheapest day to fly to Illinois?

    Based on KAYAK data, the cheapest day to fly to Illinois is Friday where round-trip tickets can be as cheap as $314. On the other hand, the most expensive day to fly is Sunday, where round-trip prices are $506 on average.

  • 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 $244 on average. Morning departures are around 10% 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 $538.

  • What is the cheapest flight to Illinois?

    The cheapest ticket to Illinois from Colorado found in the last 5 days was to Peoria, at $130 round-trip. The most popular route is Aspen (ASE) to Chicago O'Hare Intl Airport (ORD) and the cheapest round-trip airline ticket found on this route in the last 5 days was $154.

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

    The cheapest month for flights from Colorado to Illinois is November, when tickets cost $130 (return) on average. On the other hand, the most expensive months are January and February, when the average cost of round-trip tickets is $345 and $229 respectively.

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

    To get a below average price on the flight from Colorado to Illinois, you should book around 3 weeks before departure, which saves you about 33% 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 Illinois?

    From Colorado, there are direct flights to Illinois from 5 cities. The city with the most direct flights is Denver, with 597 direct flights each week.

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

    There are around 100 direct flights from within Colorado to Illinois every day. Most flights (58%) depart in the morning.

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

    Each week there are around 698 direct flights from within Colorado to Illinois. The most common day for departures is Sunday, with 16% of flights taking off on this day.

  • How long is the flight to Illinois?

    An average nonstop flight from Colorado to Illinois takes 6h 28m, covering a distance of 927 miles. The shortest route is Denver (DEN) to St. Louis (STL) with an average flight time of 1h 55m.

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

    There are not any long-haul (6-12 hour flight duration) or medium-haul (3-6 hour flight duration) flights to Illinois. Instead, there are 698 short-haul flights (up to 3 hour flight duration), with the most arriving from Denver.

  • What are the most popular destinations in Illinois?

    Based on KAYAK flight searches, the most popular destination is Chicago (84% of total searches to Illinois). The next most popular destinations are St. Louis (11%) and Peoria (2%). Searches for flights to Moline (1%), to Bloomington (1%) and to Evansville (0%) are also popular.

Reviews of the top 5 airlines serving from Colorado to Illinois

 
Need help choosing which airline to fly with from Colorado 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.
7.9
SouthwestOverall score based on 4249 reviews
8.6Crew
7.0Food
8.0Comfort
8.1Boarding
7.5Entertainment
Airline reviews

Flight was delayed over 3 hours. Planes were dirty. Staff indifferent. And they serve vegan pretzels as snacks.

2.0 MediocreMatthew, Jun 2026
CVG - MDW
Read more Southwest reviews

Flight was delayed over 3 hours. Planes were dirty. Staff indifferent. And they serve vegan pretzels as snacks.

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

The checking experience in Orlando was terrible, almost missed the flight. Too many travelers and Southwest completely understaffed.

no service at all due to turbulence. they should've at least given us snacks, there were only 10 people on the entire flight.

For the first time in a long time, the Wi-Fi actually worked the entire flight! The flight crew was amazing as usual.

Great flight. I didn't get a drink because I was asleep whole on the flight.

Love them will get a Southwest card to track my points and keep flying with them. My family and I were pleased with the services.

WiFi was not working and didn’t have a beverage service

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

Delay after delay after delay. Very disappointing I am about ready to give up on Southwest. One of the crewmembers sat and played games on her phone for the entire trip from Chicago to Baltimore. Unbelievable, very unprofessional, and very disappointing.

Horrible experience. They delayed our flight 7 hours!! We had to seat at the airport with kids on 4th July all day!

1 flight cancelled Had to fly out of different city Flight at new departure city was delayed 3 hours causing us to miss connecting flights. By the time we did make it to Prague our luggage did not. Had to wait day and a half for luggage to be delivered. Customer service was not good. Agents did not arrive at gate until 5-10 minutes before boarding

Very easy ! Use the kiosk and bag drop and right to security within 10 min

O’hsre taxi and deboarding took 40 minutes. Needed 20 minutes extra time between connecting flights to avoid running through terminal.

Every staff member was professional, friendly and courteous. The pizza twist was ok. It was warm but too much dough.

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.

Overall poor for me I paid extra for seats with leg room and my regional flights exit row seats have less leg room then the others that's money that could have been saved and on my final flight home the flights air was not operating it was unbearably hot in the cabin I will be contacting United and filing a DOT complaint

Flight was delayed by over an hour and gate checked bags took 15 minutes to be delivered to the jet bridge.

We have taken this flight before and it is a tight connection and they were late out of denver and did not wait for us. The plane was there and the departure time had not passed but would not let us on. Next flight is very late and a connection through Newark - a big mess. Sooooo appreciate them holding the plane so we could catch the connection.

Upgrade planes to have larger overhead bins, especially on this popular route and first class. Easy flight to Chicago, good service in first class. Can't wait for seatback entertainment to be brought back. I like the free wifi and messaging with T-Mobile. Although, the tray tables are not big enough to work even on a small laptop - so why is it called "business" class?

A very pleasant flight but it would be greatly improved with wifi to help entertain kids

This is a no frills, get it done, efficient airline. The seat is a lawn chair. You better bring your own entertainment. If you want something other than water you need to pay for it. But they will get you to your destination quickly, on time, and then they will turn the flight around and go right back where they came from. Reliably. Couple times a week tops. If it fits into your schedule, you can’t get there cheaper or faster.

A three hour delay to board and then another hour on the tarmac because they couldn't get a tractor? Ugh.

Allegiant canceled the flight. The flight the next day was full. Allegiant did not provide any compensation besides a refund. Last time on Allegiant.

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.

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!

My 90 year old father flew with me. He needed wheel chair assistance and is nearly deaf. The staff was amazing with him.

The flight was delayed 6 hours and we were only offered an $8 food credit. My husband stood in line to get the credit for 45 minutes and when he got close to the end of the line the computers went down.

Be just a little friendlier, instead of just doing their job and speaking because it’s their job. At least act they want to speak.

Nothing, I wont be flying American Airlines again and will not be recommending anyone to fly American Airlines. It was the worst experience flying I've ever had.

My luggage was not sent with us. Not sure if this is Envoy Air responsibility but that was a very BAD experience

The planes can use an actual cleaning. The armrest and seats do not appear to be cleaned on this one and most other planes.

Flight was delayed…once landed at ORD, no gates were available so made us wait for 56 minutes after we landed to let us out of the aircraft!

The flight de-boarded after being informed of a 3 hour delay. The gate agent said we could go to lounge. The flight ended up boarding 20 minutes later and I missed it.

I love the e fact that the staff communicated swiftly when my flight was delayed and gate number changed

We had a mechanical delay which made us 90 minutes late (9:30 PM) then land and put into the penalty box because a plane was in our gate? What the hell! We should get priority.Damn American.

The flight attendants were extremely sourly and borderline rude. I did not feel appreciated as an AA customer once.

It was great. It was just a commuter so I splurged on first class and it was wonderful. Wish all seats were this spacious. Enjoyed it and will do it again.

Deicing in Denver took forever and I almost missed my connection. De-ice faster! Not Americans fault.

Flight was scheduled at 9:40pm. Got delayed to 10 am, the next day. crazy

The bag check, flight check-in, and onboard experience convinced my wife and me that we will actively go out of our way to avoid flying Frontier Airlines in the future. At bag check, we were informed that check-in could only be completed via the Frontier mobile app. Unfortunately, the app was extremely frustrating—sending us through repetitive, confusing loops that repeatedly forced us to decline add-on services with nearly every click. While most airline apps upsell, this one felt intentionally exhausting. As the process dragged on, we became genuinely concerned that my phone battery would die before check-in could be completed. We approached the bag check staff—who were standing together talking—and explained both our frustration and our predicament. They laughed. Later, my wife described the interaction as “gaslighting,” which felt accurate. We were then informed it would cost $25 per person simply to have our boarding passes printed. From that point forward, the tone of the experience was consistently hostile. The bag check employees were condescending and combative, behaving more like bullies than customer service staff. Unfortunately, that same attitude continued onboard. One flight attendant argued with me when I attempted to stow my backpack in the overhead bin. I explained that we had each paid $75 to check our bags specifically so we would not need to use carry-on space and could have adequate legroom. She demanded to see my ticket, pointed out that it said “no carry-on”—which I acknowledged—and I reiterated that this was precisely why we paid to check our bags. Her response was, “I don’t make the rules.” She then walked away, but not before asking if I “truly wanted to fly back to Chicago today?”—an unnecessary and unmistakable threat. It is also worth noting that despite booking our tickets together in the same transaction, we were not seated together. Upon our return to Chicago—where we could once again sit together—we compared onboard experiences. We both remarked on how unhappy the flight attendants appeared and how each of us was separately asked whether we would like to purchase a beverage. We declined. At no point was water mentioned as an option, leaving us with the clear impression that even water came at a cost—or that complimentary water, if available at all, was deliberately left unmentioned. Overall, the experience was shocking and deeply disappointing, but it was also a profound learning experience—one we will not forget and will not repeat. -Steve

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.

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.

Severe turbulence. Captain never came on to reassure passengers after things settled down.

We were delayed three times ,and that destroyed my plans, and reservations

The crew was delayed because they came on another flight that was delayed due to weather 10pm flight left at 1.30 am The airline made no effort to align alternate crew

The flight itself was ok and the pilot was very communicative. However, our flight was delayed for almost 3 hours, the gate was changed 3 times and there was no communication as we were waiting. The flight staff was overall a little crabby...I understand as they probably had a long day but we all did.

Everything you need to know for your flight to Illinois

Cabin class types available on flights to Colorado

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