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$29+ Cheap flights from Illinois to Denver (DEN)

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 1/17. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — DEN
Jan 11 — Jan 181
Sun 1/11
Sun 1/18
1 adult, Economy
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Cheap flight deals from Illinois to Denver

Cheapest flights from Illinois to Denver
Explore the most affordable flight options available from Illinois to Denver. Find the lowest fares from popular airlines and budget airlines, with prices last updated on December 12, 2025.

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.
Fri 12/1912:26 pmORD - DEN
1 stop11h 43mFrontier
Thu 12/258:45 pmDEN - ORD
Nonstop2h 27mFrontier
Deal found 12/10$145
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 12/249:34 pmORD - DEN
1 stop12h 04mFrontier
Wed 12/318:45 pmDEN - ORD
Nonstop2h 27mFrontier
Deal found 12/11$171
This Super.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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/317:43 pmSTL - DEN
Nonstop2h 32mFrontier
Mon 1/56:50 amDEN - STL
Nonstop2h 12mFrontier
Deal found 12/10$172
This Frontier 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 12/2110:49 pmORD - DEN
1 stop11h 15mFrontier
Wed 12/248:45 pmDEN - ORD
Nonstop2h 27mFrontier
Deal found 12/9$175
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.
Fri 12/1912:26 pmORD - DEN
1 stop11h 43mFrontier
Thu 1/83:02 pmDEN - ORD
Nonstop2h 43mFrontier
Deal found 12/11$177
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.
Sat 12/132:26 pmORD - DEN
1 stop18h 58mFrontier
Wed 12/248:45 pmDEN - ORD
Nonstop2h 27mFrontier
Deal found 12/9$178
This CheapOair 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/317:43 pmSTL - DEN
Nonstop2h 32mFrontier
Tue 1/611:59 pmDEN - STL
1 stop21h 34mFrontier
Deal found 12/10$178
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.
Tue 12/3012:32 pmORD - DEN
1 stop10h 36mFrontier
Wed 12/318:45 pmDEN - ORD
Nonstop2h 27mFrontier
Deal found 12/10$179
This Kiwi.com 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/317:00 amORD - DEN
Nonstop2h 56mFrontier
Wed 12/318:45 pmDEN - ORD
Nonstop2h 27mFrontier
Deal found 12/11$180
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 12/247:00 amORD - DEN
Nonstop2h 56mFrontier
Thu 12/258:45 pmDEN - ORD
Nonstop2h 27mFrontier
Deal found 12/10$183
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.
Thu 12/187:00 amORD - DEN
Nonstop2h 56mFrontier
Thu 12/258:45 pmDEN - ORD
Nonstop2h 27mFrontier
Deal found 12/10$184
This United Airlines 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/248:08 pmORD - DEN
Nonstop2h 58mUnited Airlines
Thu 1/16:00 amDEN - ORD
Nonstop2h 44mUnited Airlines
Deal found 12/10$192

Find flight deals from Illinois to Denver

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

Most accurate provider

CheapOair
3 stars

Most trusted provider

CheapOair
3 stars

Round-trip from

$70
(Frontier)

One-way from

$29
(Expedia)

Popular in

December

Cheapest in

January

Average price

$269

Good round-trip deal

$171 or less

Good one-way deal

$119 or less
Provider with most accurate pricing for Chicago (CHI)-Denver Intl flight deals.
Search Deals
Provider most trusted by Cheapflights users for Chicago (CHI)-Denver Intl flights.
Search Deals
From Illinois to Denver Intl
Search Deals
One-way flight from Illinois to Denver Intl
Search Deals
Highest demand for flights based on searches. 7% potential increase in price ($16 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease ($6 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 Illinois to Denver Intl.
Search Deals
Price to beat on a one-way flight from Illinois to Denver Intl.
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Cheapflights Fare Finder

 
Customize your flight search to find flights from Illinois to Denver 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 Illinois to Denver that are best for you.

Fly from

Illinois

Fly to

Denver

Route

Depart

Return

Price

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Wed 1/7

5:11 pm-9:49 pm

2 stops29h 38m

Denver Intl

Sat 1/10

6:50 am-10:02 am

Nonstop2h 12m

$123

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Wed 1/7

7:43 pm-9:15 pm

Nonstop2h 32m

Denver Intl

Wed 1/14

10:40 am-12:40 pm

2 stops25h 00m

$131

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Sat 1/10

3:59 pm-5:57 pm

Nonstop2h 58m

Denver Intl

Sat 1/17

9:40 am-1:22 pm

Nonstop2h 42m

$168

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Thu 1/1

9:40 pm-11:38 pm

Nonstop2h 58m

Denver Intl

Wed 1/7

5:42 pm-9:15 pm

Nonstop2h 33m

$168

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Wed 1/7

7:43 pm-9:15 pm

Nonstop2h 32m

Denver Intl

Wed 1/14

9:20 pm-10:34 pm

3 stops24h 14m

$169

ChicagoDenver

MDW - DEN

MDWDEN

Chicago Midway

Wed 1/7

5:35 pm-7:20 pm

Nonstop2h 45m

Denver Intl

Wed 1/14

9:45 am-1:10 pm

Nonstop2h 25m

$179

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Sat 1/24

12:53 pm-2:51 pm

Nonstop2h 58m

Denver Intl

Tue 1/27

5:42 pm-9:15 pm

Nonstop2h 33m

$179

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Wed 1/7

8:02 pm-9:59 pm

Nonstop2h 57m

Denver Intl

Tue 1/13

5:42 pm-9:15 pm

Nonstop2h 33m

$179

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Sat 1/31

3:59 pm-5:57 pm

Nonstop2h 58m

Denver Intl

Tue 2/3

8:25 pm-11:59 pm

Nonstop2h 34m

$179

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Tue 2/17

12:50 pm-2:48 pm

Nonstop2h 58m

Denver Intl

Sat 2/21

5:54 pm-9:29 pm

Nonstop2h 35m

$179

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 Illinois to Denver

Have a flexible travel schedule? Discover the best time to fly to Denver from Illinois 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 Illinois to Denver

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

Currently, September is the cheapest month in which you can book a flight from Illinois to Denver (average of $49). Flying from Illinois to Denver in July is currently the most expensive (average of $115). 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 IL to DEN?

Find hourly flight availability from Illinois to Denver. 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.

A simple way to save on the total cost of your ticket is to fly from Illinois to Denver in the evening. If you’re flexible enough to do this you can expect to save up to 46% on your trip compared to booking a flight at noon.

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

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

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

Weekly flight availability from Illinois to Denver

Explore weekly flight availability from Illinois to Denver. 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 USIL to DEN are scheduled on a Thursday (46 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (22 on average).

Related info for your journey

Find useful and relevant information for your journey from Illinois to Denver. 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 into for flights to Denver from Illinois?

    For a flight from Illinois to Denver, you will be flying into Denver Intl. Denver Intl (DEN) is just 18.5 mi from the center of the city.

  • How long is the flight from Illinois to Denver?

    Airlines like Frontier, United Airlines, and Southwest fly from Illinois to Denver in about 2h 45m. The time it takes to get you to your destination can typically vary by up to 26h 53m. Airlines will cover a distance of 893 mi. This flight may include one or multiple stops.

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

    The cheapest airlines for a one-way flight from Illinois to Denver are Frontier ($37), Allegiant Air ($58), and American Airlines ($75).

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

    While some choose either Chicago Midway - Denver Intl or Lambert-St Louis - Denver Intl, Chicago O'Hare Intl - Denver Intl is the most popular route from Illinois to Denver.

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

    The top 3 most reliable airlines when flying from Illinois to Denver are Qatar Airways (84%), American Airlines (79%) and Iberia (78%).

  • What are the cheapest flights from Illinois to Denver?

    While on average a flight from Illinois to Denver is generally $950, our data shows the cheapest flight currently is $51. When looking at the most popular route, (Chicago O'Hare Intl - Denver Intl), you can expect to pay $88 for that flight.

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

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

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

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

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

    Yes. Cheapflights offers flight deals from Illinois to Denver 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 Illinois to Denver?

    Currently, September is the cheapest month in which you can book a flight from Illinois to Denver (average of $49). Flying from Illinois to Denver in July is currently the most expensive (average of $115). 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

Traveling to a place near Denver?

Book flights to Denver if you plan to visit one of these locations
Black Hawk
Thornton
Westminster
Broomfield
Lakewood
Golden
Winter Park
Greeley
Lone Tree
Cripple Creek
Silverthorne
Central City
Frisco
Wheat Ridge
Manitou Springs
Fort Morgan
Brighton
Longmont
Idaho Springs
Parker

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Alternative routes for Illinois to Denver

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Top 5 airlines flying from Illinois to Denver

Discover the top 5 airlines that operate flights from Illinois to Denver. 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$58Average$161FlexibilityNo cancel feeOn-time62%
Allegiant AirCheapest$74Average$147FlexibilityNo cancel feeOn-time88%
American AirlinesCheapest$153Average$358FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$156Average$353FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$157Average$256FlexibilityNo cancel feeOn-time63%

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