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$38+ 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 2/10. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — DEN
Jan 26 — Feb 21
Sun 1/26
Sun 2/2
1 adult, Economy
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Cheap flight deals from Illinois to Denver

Discover tips and strategies to find the most affordable flight options for your journey from Illinois (USIL) to Denver (DEN). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated January 21, 2025.

Round-trip from

$57
(Cheapflightsfares)

One-way from

$38
(Mytrip)

Good round-trip deal

$127 or less

Good one-way deal

$58 or less
From Illinois to Denver Intl
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One-way flight from Illinois to Denver Intl
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Price to beat on a round-trip flight from Illinois to Denver Intl.
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Price to beat on a one-way flight from Illinois to Denver Intl.
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Find 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 January 21, 2025.

This Frontier deal was found by Cheapflights users on 1/19. 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.
Sat 2/157:04 pmSTL - DEN
Nonstop2h 28mFrontier
Wed 2/266:00 amDEN - STL
Nonstop2h 16mFrontier
Deal found 1/19$58
This Frontier deal was found by Cheapflights users on 1/20. 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.
Sat 2/156:40 amMDW - DEN
Nonstop2h 52mFrontier
Tue 2/188:55 pmDEN - MDW
Nonstop2h 22mFrontier
Deal found 1/20$79
This Frontier deal was found by Cheapflights users on 1/20. 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 2/206:50 amORD - DEN
Nonstop3h 03mFrontier
Sat 2/221:52 pmDEN - ORD
Nonstop2h 33mFrontier
Deal found 1/20$79
This Mytrip deal was found by Cheapflights users on 1/20. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 3/33:11 pmPIA - DEN
Nonstop2h 28mAllegiant Air
Fri 3/75:32 pmDEN - PIA
Nonstop2h 05mAllegiant Air
Deal found 1/20$92
This Southwest deal was found by Cheapflights users on 1/20. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 3/15:35 amMDW - DEN
Nonstop2h 55mSouthwest
Mon 3/36:05 amDEN - MDW
Nonstop2h 30mSouthwest
Deal found 1/20$168
This American Airlines deal was found by Cheapflights users on 1/20. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 3/19:09 pmORD - DEN
Nonstop2h 47mAmerican Airlines
Mon 3/37:00 amDEN - ORD
Nonstop2h 43mAmerican Airlines
Deal found 1/20$169
This Orbitz deal was found by Cheapflights users on 1/20. 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 Orbitz is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 2/111:40 pmORD - DEN
1 stop4h 00mMultiple Airlines
Wed 2/199:53 amDEN - ORD
Nonstop2h 32mMultiple Airlines
Deal found 1/20$194
This Delta deal was found by Cheapflights users on 1/20. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 2/195:00 pmSTL - DEN
1 stop6h 47mDelta
Tue 2/254:15 pmDEN - STL
1 stop5h 02mDelta
Deal found 1/20$197
This United Airlines deal was found by Cheapflights users on 1/19. 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.
Sat 5/106:00 pmORD - DEN
Nonstop2h 55mUnited Airlines
Sat 5/178:57 pmDEN - ORD
Nonstop2h 32mUnited Airlines
Deal found 1/19$205
This American Airlines deal was found by Cheapflights users on 1/20. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 2/274:23 pmMLI - DEN
1 stop7h 57mAmerican Airlines
Mon 3/36:30 amDEN - MLI
1 stop8h 21mAmerican Airlines
Deal found 1/20$209
This Southwest deal was found by Cheapflights users on 1/19. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 2/186:35 amSTL - DEN
Nonstop2h 35mSouthwest
Tue 2/255:50 amDEN - STL
1 stop5h 25mSouthwest
Deal found 1/19$217
This Delta deal was found by Cheapflights users on 1/21. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 3/49:33 amMDW - DEN
1 stop5h 23mDelta
Mon 3/1012:55 amDEN - MDW
1 stop7h 14mDelta
Deal found 1/21$217

Find flights from Illinois to Denver within your budget

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 January 21, 2025.

Fly from

Any airport

Fly to

Any airport

Route

Depart

Return

Price

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Sat 2/8

7:09 pm-8:37 pm

Nonstop2h 28m

Denver Intl

Wed 2/12

6:00 am-9:16 am

Nonstop2h 16m

$57

ChicagoDenver

MDW - DEN

MDWDEN

Chicago Midway

Sat 2/15

6:40 am-8:32 am

Nonstop2h 52m

Denver Intl

Tue 2/18

8:55 pm-12:17 am

Nonstop2h 22m

$79

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Thu 2/20

6:50 am-8:53 am

Nonstop3h 03m

Denver Intl

Sat 2/22

1:52 pm-5:25 pm

Nonstop2h 33m

$79

PeoriaDenver

PIA - DEN

PIADEN

Greater Peoria

Mon 3/3

3:11 pm-4:39 pm

Nonstop2h 28m

Denver Intl

Fri 3/7

5:32 pm-8:37 pm

Nonstop2h 05m

$92

ChicagoDenver

MDW - DEN

MDWDEN

Chicago Midway

Sat 3/1

9:15 pm-11:00 pm

Nonstop2h 45m

Denver Intl

Mon 3/3

6:05 am-9:35 am

Nonstop2h 30m

$168

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Sat 3/1

9:09 pm-10:56 pm

Nonstop2h 47m

Denver Intl

Mon 3/3

7:00 am-10:43 am

Nonstop2h 43m

$169

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Tue 2/11

1:40 pm-4:40 pm

1 stop4h 00m

Denver Intl

Wed 2/19

9:53 am-1:25 pm

Nonstop2h 32m

$194

St. LouisDenver

STL - DEN

STLDEN

Lambert-St Louis

Wed 2/19

5:00 pm-10:47 pm

1 stop6h 47m

Denver Intl

Tue 2/25

4:15 pm-10:17 pm

1 stop5h 02m

$197

ChicagoDenver

ORD - DEN

ORDDEN

Chicago O'Hare Intl

Sat 5/10

6:00 pm-7:55 pm

Nonstop2h 55m

Denver Intl

Sat 5/17

8:57 pm-12:29 am

Nonstop2h 32m

$205

MolineDenver

MLI - DEN

MLIDEN

Moline Quad-City

Thu 2/27

4:23 pm-11:20 pm

1 stop7h 57m

Denver Intl

Mon 3/3

6:30 am-3:51 pm

1 stop8h 21m

$209

Flights are sorted by cheapest round-trip flights first.

Deals found on 1/21

Showing 1-10 of 58 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.

Travel insights for flights from Illinois to Denver

Get recent, data-driven insights about flights from Illinois to Denver including ideal travel times, pricing trends, and more.

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

Currently, October is the cheapest month in which you can book a flight from Illinois to Denver (average of $197). Flying from Illinois to Denver in March is currently the most expensive (average of $278). 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 January 21, 2025.

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

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 January 21, 2025.

The most flights from USIL to DEN are scheduled on a Monday (42 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (30 on average).

Rainfall in Denver by month

Plan your trip to Denver by taking into account the average rainfall totals by month.

In terms of precipitation, rainfall in Denver ranges from 0.5 - 2.3 inches per month. May is typically the wettest month, when rainfall can reach 2.3 in. January is typically the driest time to visit Denver when rainfall is around 0.5 in.

Temperature in Denver by month

Plan your trip to Denver by taking into account the average temperature totals by month.

If weather is an important factor for your trip to Denver, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 73.4 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 30.2 F).

Reviews of airlines servicing Denver

Get insights into the airlines that provide service to Denver. 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 Denver. Reviews last updated January 21, 2025.
Get a feel of what it's like to fly with Delta, Frontier and Allegiant Air from Illinois to Denver by reading reviews from past customers. In addition to providing an overall rating, users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.1
Very good
4,662 reviews

Overall

8.1

Food

7.2

Entertainment

7.7

Comfort

8.1

Crew

8.7

Boarding

8.2

Reviews

1 / 10

We BARELY made the connection and when we got onboard we were treated like disobedient children who should have arrived earlier because we had to ask other passengers to move so we could sit with our kids. The flight attendants on the first flight were nice but the second one, they were snippy and fairly rude.

Southwest
8.1
Very good
4,662 reviews
Southwest
8.1
Very good
4,662 reviews

Overall

8.1

Food

7.2

Entertainment

7.7

Comfort

8.1

Crew

8.7

Boarding

8.2

Reviews

1 / 10

We BARELY made the connection and when we got onboard we were treated like disobedient children who should have arrived earlier because we had to ask other passengers to move so we could sit with our kids. The flight attendants on the first flight were nice but the second one, they were snippy and fairly rude.

Alaska Airlines
8.0
Very good
9,706 reviews
Southwest
8.1
Very good
4,662 reviews

Overall

8.1

Food

7.2

Entertainment

7.7

Comfort

8.1

Crew

8.7

Boarding

8.2

Reviews

1 / 10

We BARELY made the connection and when we got onboard we were treated like disobedient children who should have arrived earlier because we had to ask other passengers to move so we could sit with our kids. The flight attendants on the first flight were nice but the second one, they were snippy and fairly rude.

Delta
8.0
Very good
8,521 reviews
Southwest
8.1
Very good
4,662 reviews

Overall

8.1

Food

7.2

Entertainment

7.7

Comfort

8.1

Crew

8.7

Boarding

8.2

Reviews

1 / 10

We BARELY made the connection and when we got onboard we were treated like disobedient children who should have arrived earlier because we had to ask other passengers to move so we could sit with our kids. The flight attendants on the first flight were nice but the second one, they were snippy and fairly rude.

United Airlines
7.4
Good
8,985 reviews
Southwest
8.1
Very good
4,662 reviews

Overall

8.1

Food

7.2

Entertainment

7.7

Comfort

8.1

Crew

8.7

Boarding

8.2

Reviews

1 / 10

We BARELY made the connection and when we got onboard we were treated like disobedient children who should have arrived earlier because we had to ask other passengers to move so we could sit with our kids. The flight attendants on the first flight were nice but the second one, they were snippy and fairly rude.

Allegiant Air
7.4
Good
801 reviews
Southwest
8.1
Very good
4,662 reviews

Overall

8.1

Food

7.2

Entertainment

7.7

Comfort

8.1

Crew

8.7

Boarding

8.2

Reviews

1 / 10

We BARELY made the connection and when we got onboard we were treated like disobedient children who should have arrived earlier because we had to ask other passengers to move so we could sit with our kids. The flight attendants on the first flight were nice but the second one, they were snippy and fairly rude.

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.

  • 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 Allegiant Air ($38), Frontier ($44), and United Airlines ($70).

  • 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 Envoy Air (100%), Royal Jordanian (93%) and Frontier (90%).

  • What are the cheapest flights from Illinois to Denver?

    While on average a flight from Illinois to Denver is generally $645, our data shows the cheapest flight currently is $74. When looking at the most popular route, (Chicago O'Hare Intl - Denver Intl), you can expect to pay $85 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, October is the cheapest month in which you can book a flight from Illinois to Denver (average of $197). Flying from Illinois to Denver in March is currently the most expensive (average of $278). 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 Illinois?

Book flights to Illinois if you plan to visit one of these locations
Keystone
Westminster
Black Hawk
Winter Park
Dillon
Lakewood
Broomfield
Silverthorne
Golden
Brighton
Frisco
Wheat Ridge
Grand Lake
Idaho Springs
Greeley
Central City
Copper Mountain
Longmont
Thornton
Limon

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Alternative routes for Illinois to Denver

See prices for flight routes from nearby airports that may be better suited for you.
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Top 6 airlines flying from Illinois to Denver

Discover the top 6 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 January 21, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$40Average$150FlexibilityNo cancel feeOn-time62%
Allegiant AirCheapest$91Average$172FlexibilityNo cancel feeOn-time88%
American AirlinesCheapest$140Average$376FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$151Average$340FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$157Average$256FlexibilityNo cancel feeOn-time63%
DeltaCheapest$185Average$258FlexibilityNo cancel feeOn-timeN/A
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