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$28+ 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 1/24. Fares are subject to change and may not be available on all flights or dates of travel.
DEN — ORD
Jan 11 — Jan 181
Sun 1/11
Sun 1/18
1 adult, Economy
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Cheap 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 December 12, 2025.

This Super.com deal was found by Cheapflights users on 12/9. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/318:45 pmDEN - ORD
Nonstop2h 27mFrontier
Mon 1/57:00 amORD - DEN
Nonstop2h 56mFrontier
Deal found 12/9$109
This Kiwi.com deal was found by Cheapflights users on 12/10. 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.
Wed 12/318:45 pmDEN - ORD
Nonstop2h 27mFrontier
Sat 1/108:35 amORD - DEN
1 stop12h 50mFrontier
Deal found 12/10$112
This Kiwi.com deal was found by Cheapflights users on 12/10. 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.
Wed 12/318:45 pmDEN - ORD
Nonstop2h 27mMultiple Airlines
Wed 1/74:38 pmORD - DEN
1 stop9h 45mMultiple Airlines
Deal found 12/10$119
This Frontier deal was found by Cheapflights users on 12/10. 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.
Wed 12/318:45 pmDEN - ORD
Nonstop2h 27mFrontier
Thu 1/85:50 amORD - DEN
1 stop7h 31mFrontier
Deal found 12/10$120
This Kiwi.com deal was found by Cheapflights users on 12/9. 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.
Wed 12/318:45 pmDEN - ORD
Nonstop2h 27mMultiple Airlines
Tue 1/69:09 pmORD - DEN
1 stop13h 48mMultiple Airlines
Deal found 12/9$121
This CheapOair deal was found by Cheapflights users on 12/9. 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.
Thu 12/258:45 pmDEN - ORD
Nonstop2h 27mFrontier
Sun 1/410:49 pmORD - DEN
1 stop25h 39mFrontier
Deal found 12/9$122
This Kiwi.com deal was found by Cheapflights users on 12/9. 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.
Wed 12/318:45 pmDEN - ORD
Nonstop2h 27mFrontier
Sun 1/410:49 pmORD - DEN
1 stop30h 09mFrontier
Deal found 12/9$130
This Kiwi.com deal was found by Cheapflights users on 12/9. 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.
Wed 12/318:45 pmDEN - ORD
Nonstop2h 27mFrontier
Sat 1/37:00 amORD - DEN
Nonstop2h 56mFrontier
Deal found 12/9$136
This Frontier deal was found by Cheapflights users on 12/11. 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.
Wed 12/316:50 amDEN - STL
Nonstop2h 12mFrontier
Wed 1/77:43 pmSTL - DEN
Nonstop2h 32mFrontier
Deal found 12/11$138
This Super.com deal was found by Cheapflights users on 12/9. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/248:45 pmDEN - ORD
Nonstop2h 27mFrontier
Wed 12/317:00 amORD - DEN
Nonstop2h 56mFrontier
Deal found 12/9$140
This Frontier deal was found by Cheapflights users on 12/11. 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.
Wed 12/316:50 amDEN - STL
Nonstop2h 12mFrontier
Fri 1/97:43 pmSTL - DEN
Nonstop2h 32mFrontier
Deal found 12/11$153
This Cheapflightsfares deal was found by Cheapflights users on 12/9. 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.
Mon 12/295:54 pmDEN - PIA
Nonstop1h 57mAllegiant Air
Mon 1/53:38 pmPIA - DEN
Nonstop2h 26mAllegiant Air
Deal found 12/9$155

Find flight deals from Denver to Illinois

Keep the following information in mind while searching for Denver to Illinois flight deals. Data was last updated December 12, 2025.

Most accurate provider

CheapOair
3 stars

Most trusted provider

CheapOair
3 stars

Round-trip from

$92
(Frontier)

One-way from

$28
(Kiwi.com)

Popular in

November

Cheapest in

January

Average price

$241

Good round-trip deal

$139 or less

Good one-way deal

$113 or less
Provider with most accurate pricing for Denver Intl-Chicago (CHI) flight deals.
Search Deals
Provider most trusted by Cheapflights users for Denver Intl-Chicago (CHI) flights.
Search Deals
From Denver Intl to Illinois
Search Deals
One-way flight from Denver Intl to Illinois
Search Deals
Highest demand for flights based on searches. 11% potential increase in price ($28 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 1% potential price decrease ($4 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in December 2025
Search Deals
Price to beat on a round-trip flight from Denver Intl to Illinois.
Search Deals
Price to beat on a one-way flight from Denver Intl to Illinois.
Search Deals

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 December 12, 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

DenverPeoria

DEN - PIA

DENPIA

Denver Intl

Mon 12/29

5:54 pm-8:51 pm

Nonstop1h 57m

Greater Peoria

Mon 1/5

3:38 pm-5:04 pm

Nonstop2h 26m

$155

DenverSt. Louis

DEN - STL

DENSTL

Denver Intl

Fri 1/9

6:50 am-10:02 am

Nonstop2h 12m

Lambert-St Louis

Sun 1/11

12:37 pm-3:58 am

1 stop16h 21m

$165

DenverSt. Louis

DEN - STL

DENSTL

Denver Intl

Wed 1/7

9:45 pm-12:12 pm

1 stop13h 27m

Lambert-St Louis

Sun 1/11

5:11 pm-5:59 pm

2 stops25h 48m

$180

DenverChicago

DEN - ORD

DENORD

Denver Intl

Wed 1/7

3:15 pm-6:46 pm

Nonstop2h 31m

Chicago O'Hare Intl

Thu 1/8

8:02 pm-9:59 pm

Nonstop2h 57m

$187

DenverChicago

DEN - ORD

DENORD

Denver Intl

Mon 1/12

4:15 pm-7:51 pm

Nonstop2h 36m

Chicago O'Hare Intl

Wed 1/14

12:53 pm-2:51 pm

Nonstop2h 58m

$187

DenverChicago

DEN - ORD

DENORD

Denver Intl

Thu 2/19

7:23 pm-10:52 pm

Nonstop2h 29m

Chicago O'Hare Intl

Mon 2/23

8:07 pm-10:05 pm

Nonstop2h 58m

$195

DenverChicago

DEN - MDW

DENMDW

Denver Intl

Thu 1/8

9:45 am-1:10 pm

Nonstop2h 25m

Chicago Midway

Sun 1/11

11:20 am-1:05 pm

Nonstop2h 45m

$196

DenverChicago

DEN - ORD

DENORD

Denver Intl

Sat 1/17

6:05 am-1:08 pm

1 stop6h 03m

Chicago O'Hare Intl

Sun 1/18

6:50 am-1:33 pm

1 stop7h 43m

$197

DenverChicago

DEN - ORD

DENORD

Denver Intl

Sat 1/17

6:05 am-1:08 pm

1 stop6h 03m

Chicago O'Hare Intl

Tue 1/20

5:30 am-1:37 pm

1 stop9h 07m

$197

DenverChicago

DEN - MDW

DENMDW

Denver Intl

Fri 1/16

2:20 pm-7:45 pm

1 stop4h 25m

Chicago Midway

Tue 1/20

2:10 pm-3:50 pm

Nonstop2h 40m

$197

Flights are sorted by cheapest round-trip flights first.

Deals found on 12/11

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, July is the cheapest month in which you can book a flight from Denver to Illinois (average of $46). Flying from Denver to Illinois in June is currently the most expensive (average of $109). 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 December 12, 2025.

It’s optimal to fly from Denver to Illinois in the morning. By choosing this option you can save up to 22% on the cost of your flight, compared to a flight at noon.

What is the cheapest day to fly from Denver to Illinois?

Use this chart to determine the cheapest time to fly round-trip from Denver to Illinois. Price data was last updated on December 16, 2024.

Travelers seeking maximum savings on their Denver to Illinois flight should consider departing on Tuesday mornings when fares are most often at their lowest. Sunday afternoons flights should be avoided if possible as fares are typically the most expensive at this time.

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 December 12, 2025.

The most flights from DEN to USIL are scheduled on a Monday (47 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (27 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 December 12, 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
7.9
Good
4,253 reviews

Entertainment

7.5

Crew

8.6

Boarding

8.1

Overall

7.9

Food

7.0

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
Southwest
7.9
Good
4,253 reviews
Southwest
7.9
Good
4,253 reviews

Entertainment

7.5

Crew

8.6

Boarding

8.1

Overall

7.9

Food

7.0

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
United Airlines
7.4
Good
9,095 reviews
Southwest
7.9
Good
4,253 reviews

Entertainment

7.5

Crew

8.6

Boarding

8.1

Overall

7.9

Food

7.0

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
American Airlines
7.2
Good
11,049 reviews
Southwest
7.9
Good
4,253 reviews

Entertainment

7.5

Crew

8.6

Boarding

8.1

Overall

7.9

Food

7.0

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
Allegiant Air
7.2
Good
699 reviews
Southwest
7.9
Good
4,253 reviews

Entertainment

7.5

Crew

8.6

Boarding

8.1

Overall

7.9

Food

7.0

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
Frontier
5.8
Fair
3,084 reviews
Southwest
7.9
Good
4,253 reviews

Entertainment

7.5

Crew

8.6

Boarding

8.1

Overall

7.9

Food

7.0

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am

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 1h 57m. Fly via Allegiant Air, Frontier, or United Airlines to get the fastest option. Denver and Illinois are separated by a distance of 790 mi. All flights are typically nonstop.

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

    $37 is the cheapest one-way deal found within the past few days, from Frontier. You may also be able to find cheap deals on Allegiant Air and Southwest, with prices starting from $53 and $75, 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 (92%), Austrian Airlines (88%) or Frontier (87%) 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 $40. While the most popular route (Denver Intl - Chicago O'Hare Intl) can be booked for $124 on average, our data indicates $886 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, July is the cheapest month in which you can book a flight from Denver to Illinois (average of $46). Flying from Denver to Illinois in June is currently the most expensive (average of $109). 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.

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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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Denver to Indianapolis flights
Denver to Milwaukee flights
Denver to Jacksonville flights

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 December 12, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$64Average$171FlexibilityNo cancel feeOn-time62%
Allegiant AirCheapest$77Average$142FlexibilityNo cancel feeOn-time88%
SouthwestCheapest$155Average$261FlexibilityNo cancel feeOn-time63%
American AirlinesCheapest$156Average$428FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$164Average$352FlexibilityNo cancel feeOn-time69%

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