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$42+ Cheap flights from Denver (DEN) to Illinois

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 10/13. Fares are subject to change and may not be available on all flights or dates of travel.
DEN — ORD
Oct 16 — Oct 231
Thu 10/16
Thu 10/23
1 adult, Economy
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Cheap flight deals from Denver to Illinois

Keep the following information in mind while searching for Denver to Illinois flight deals. Data was last updated September 16, 2025.

Round-trip from

$96
(Kiwi.com)

One-way from

$42
(Kiwi.com)

Popular in

May

Cheapest in

October

Average price

$195

Good round-trip deal

$113 or less

Good one-way deal

$92 or less
From Denver Intl to Illinois
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One-way flight from Denver Intl to Illinois
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Highest demand for flights based on searches. 9% potential increase in price ($20 potential increase over avg. RT price).
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Cheapest flight prices on average. 1% potential price decrease ($2 potential savings vs. average RT price).
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Average for round-trip flights in September 2025
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Price to beat on a round-trip flight from Denver Intl to Illinois.
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Price to beat on a one-way flight from Denver Intl to Illinois.
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Find flight deals from Denver to Illinois

Cheapest flights from Denver to Illinois
Explore the most affordable flight options available from Denver to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on September 16, 2025.

This Kiwi.com deal was found by Cheapflights users on 9/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/166:00 amDEN - STL
Nonstop2h 07mFrontier
Mon 10/207:52 pmSTL - DEN
Nonstop2h 28mFrontier
Deal found 9/15$96
This Priceline deal was found by Cheapflights users on 9/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/136:00 amDEN - STL
Nonstop2h 07mFrontier
Mon 10/207:52 pmSTL - DEN
Nonstop2h 28mFrontier
Deal found 9/15$97
This Frontier deal was found by Cheapflights users on 9/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/246:00 amDEN - STL
Nonstop2h 07mFrontier
Wed 10/298:40 pmSTL - DEN
Nonstop2h 30mFrontier
Deal found 9/16$99
This Cheapflightsfares deal was found by Cheapflights users on 9/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/86:00 amDEN - STL
Nonstop2h 07mFrontier
Sun 10/127:52 pmSTL - DEN
Nonstop2h 28mFrontier
Deal found 9/14$101
This Kiwi.com deal was found by Cheapflights users on 9/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/316:00 amDEN - STL
Nonstop2h 07mFrontier
Sun 11/27:45 pmSTL - DEN
Nonstop2h 28mFrontier
Deal found 9/16$102
This Cheapflightsfares deal was found by Cheapflights users on 9/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/266:00 amDEN - STL
Nonstop2h 06mFrontier
Sat 9/277:55 pmSTL - DEN
Nonstop2h 25mFrontier
Deal found 9/14$108
This Priceline deal was found by Cheapflights users on 9/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/1212:59 amDEN - STL
1 stop8h 13mFrontier
Sun 11/167:45 pmSTL - DEN
Nonstop2h 28mFrontier
Deal found 9/14$109
This Kiwi.com deal was found by Cheapflights users on 9/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/246:00 amDEN - STL
Nonstop2h 07mFrontier
Thu 10/308:40 pmSTL - DEN
Nonstop2h 30mFrontier
Deal found 9/16$110
This Priceline deal was found by Cheapflights users on 9/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/118:00 amDEN - STL
1 stop6h 56mFrontier
Tue 10/147:52 pmSTL - DEN
Nonstop2h 28mFrontier
Deal found 9/14$112
This Gotogate deal was found by Cheapflights users on 9/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/236:00 amDEN - STL
Nonstop2h 07mFrontier
Mon 10/2712:38 pmSTL - DEN
1 stop16h 21mFrontier
Deal found 9/15$113
This Kiwi.com deal was found by Cheapflights users on 9/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 10/126:00 amDEN - ORD
Nonstop2h 36mFrontier
Thu 10/166:50 amORD - DEN
Nonstop2h 41mFrontier
Deal found 9/15$116
This CheapOair deal was found by Cheapflights users on 9/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/277:49 amDEN - MDW
Nonstop2h 27mFrontier
Fri 10/311:37 pmMDW - DEN
1 stop8h 53mFrontier
Deal found 9/13$116

Cheapflights Fare Finder

 
Customize your flight search to find flights from Denver to Illinois that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated September 16, 2025.
Use the filters below to find and compare flights from Denver to Illinois that are best for you.

Fly from

Denver

Fly to

Illinois

Route

Depart

Return

Price

DenverSt. Louis

DEN - STL

DENSTL

Denver Intl

Fri 10/10

8:45 pm-11:58 pm

Nonstop2h 13m

Lambert-St Louis

Thu 10/16

5:15 am-6:53 am

Nonstop2h 38m

$131

DenverSt. Louis

DEN - STL

DENSTL

Denver Intl

Wed 11/12

10:15 am-1:20 pm

Nonstop2h 05m

Lambert-St Louis

Sat 11/15

12:20 pm-5:50 pm

2 stops6h 30m

$146

DenverSt. Louis

DEN - STL

DENSTL

Denver Intl

Wed 10/15

10:15 am-5:25 pm

1 stop6h 10m

Lambert-St Louis

Tue 10/21

2:55 pm-7:45 pm

1 stop5h 50m

$151

DenverChicago

DEN - ORD

DENORD

Denver Intl

Thu 10/16

4:45 pm-8:25 pm

Nonstop2h 40m

Chicago O'Hare Intl

Mon 10/20

9:44 pm-11:30 pm

Nonstop2h 46m

$157

DenverChicago

DEN - MDW

DENMDW

Denver Intl

Sat 1/17

5:30 am-9:00 am

Nonstop2h 30m

Chicago Midway

Mon 1/19

5:40 am-7:30 am

Nonstop2h 50m

$157

DenverChicago

DEN - MDW

DENMDW

Denver Intl

Sat 10/18

8:15 am-11:40 am

Nonstop2h 25m

Chicago Midway

Mon 10/20

9:50 pm-11:25 pm

Nonstop2h 35m

$157

DenverSt. Louis

DEN - STL

DENSTL

Denver Intl

Thu 10/30

2:04 pm-8:26 pm

1 stop5h 22m

Lambert-St Louis

Sat 11/1

5:09 pm-10:12 pm

1 stop6h 03m

$159

DenverChicago

DEN - MDW

DENMDW

Denver Intl

Sat 10/18

9:35 am-4:45 pm

1 stop6h 10m

Chicago Midway

Wed 10/22

2:45 pm-4:20 pm

Nonstop2h 35m

$167

DenverChicago

DEN - MDW

DENMDW

Denver Intl

Tue 10/7

7:55 am-12:40 pm

1 stop3h 45m

Chicago Midway

Tue 10/7

8:40 pm-10:20 pm

Nonstop2h 40m

$167

DenverChicago

DEN - MDW

DENMDW

Denver Intl

Mon 11/17

10:20 am-4:55 pm

1 stop5h 35m

Chicago Midway

Wed 11/19

9:40 am-11:20 am

Nonstop2h 40m

$167

Flights are sorted by cheapest round-trip flights first.

Deals found on 9/14

Showing 1-10 of 60 results
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Best time to book a flight from Denver to Illinois

Have a flexible travel schedule? Discover the best time to fly to Illinois from Denver with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

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

What is the cheapest month to book a flight from Denver to Illinois?

Currently, August is the cheapest month in which you can book a flight from Denver to Illinois (average of $245). Flying from Denver to Illinois in March is currently the most expensive (average of $321). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

What is the cheapest time of day to fly from DEN to IL?

Find hourly flight availability from Denver to Illinois. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated September 16, 2025.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Denver to Illinois as you normally would.

Weekly flight availability from Denver to Illinois

Explore weekly flight availability from Denver to Illinois. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated September 16, 2025.

The most flights from DEN to USIL are scheduled on a Monday (65 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (37 on average).

Reviews of airlines servicing Illinois

Get insights into the airlines that provide service to Illinois. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Illinois. Reviews last updated September 16, 2025.
Read through reviews of airlines operating flights from Denver to Illinois, such as Southwest, United Airlines, and American Airlines. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.0
Very good
4,242 reviews

Boarding

8.1

Crew

8.6

Entertainment

7.5

Overall

8.0

Food

7.0

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
Southwest
8.0
Very good
4,242 reviews
Southwest
8.0
Very good
4,242 reviews

Boarding

8.1

Crew

8.6

Entertainment

7.5

Overall

8.0

Food

7.0

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
United Airlines
7.4
Good
8,924 reviews
Southwest
8.0
Very good
4,242 reviews

Boarding

8.1

Crew

8.6

Entertainment

7.5

Overall

8.0

Food

7.0

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
American Airlines
7.2
Good
10,000 reviews
Southwest
8.0
Very good
4,242 reviews

Boarding

8.1

Crew

8.6

Entertainment

7.5

Overall

8.0

Food

7.0

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
Allegiant Air
7.2
Good
699 reviews
Southwest
8.0
Very good
4,242 reviews

Boarding

8.1

Crew

8.6

Entertainment

7.5

Overall

8.0

Food

7.0

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
Frontier
5.8
Fair
3,174 reviews
Southwest
8.0
Very good
4,242 reviews

Boarding

8.1

Crew

8.6

Entertainment

7.5

Overall

8.0

Food

7.0

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines

Related info for your journey

Find useful and relevant information for your journey from Denver to Illinois. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airport do you fly from for flights from Denver to Illinois?

    Most people fly from Denver Intl (DEN) if they book a flight from Denver to Illinois. Denver Intl is conveniently located just 18.5 mi from Denver’s city center.

  • How long is the flight from Denver to Illinois?

    There are many flights that can get you from Denver to Illinois in 2h 05m. Fly via United Airlines, Southwest, or American Airlines to get the fastest option. Denver and Illinois are separated by a distance of 767 mi. This flight may include one or multiple stops.

  • What are the cheapest airlines to fly from Denver to Illinois one-way?

    $66 is the cheapest one-way deal found within the past few days, from United Airlines. You may also be able to find cheap deals on Southwest and Allegiant Air, with prices starting from $79 and $133, respectively.

  • What are the most popular routes from Denver to Illinois?

    When deciding which route to take from Denver to Illinois consider Denver Intl - Chicago O'Hare Intl, Denver Intl - Chicago Midway or Denver Intl - Lambert-St Louis as they are the most popular.

  • What are the most reliable airlines from Denver to Illinois?

    No one likes to see their flight delayed. When booking a flight from Denver to Illinois consider choosing Japan Airlines (85%), Cathay Pacific (85%) or Turkish Airlines (85%) as they are the most reliable in getting you off to your destination on time.

  • What are the cheapest flights from Denver to Illinois?

    Looking at all options, your cheapest flight can be booked for $61. While the most popular route (Denver Intl - Chicago O'Hare Intl) can be booked for $119 on average, our data indicates $1,041 when flying from Denver to Illinois.

  • Can I find deals for flights from Denver to Illinois that include hotel bookings?

    Yes. In addition to deals on Denver to Illinois flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Denver to Illinois?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Denver to Illinois.

  • Can I find deals for business class flights from Denver to Illinois?

    Yes. Cheapflights offers flight deals from Denver to Illinois by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from Denver to Illinois?

    Currently, August is the cheapest month in which you can book a flight from Denver to Illinois (average of $245). Flying from Denver to Illinois in March is currently the most expensive (average of $321). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

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Alternative routes for Denver to Illinois

See prices for flight routes from nearby airports that may be better suited for you.
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Top 5 airlines flying from Denver to Illinois

Discover the top 5 airlines that operate flights from Denver to Illinois. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated September 16, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$62Average$165FlexibilityNo cancel feeOn-time62%
Allegiant AirCheapest$77Average$155FlexibilityNo cancel feeOn-time88%
SouthwestCheapest$152Average$252FlexibilityNo cancel feeOn-time63%
American AirlinesCheapest$156Average$398FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$165Average$361FlexibilityNo cancel feeOn-time69%

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