$27+ Cheap flights from Illinois to Colorado
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 5/26. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — DEN
Jun 1 — Jun 81
Round-trip
1 adult, Economy
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Cheapest flights from Illinois to ColoradoExplore the most affordable flight options available from Illinois to Colorado. Find the lowest fares from popular airlines and budget airlines, with prices last updated on May 2, 2026.
Explore the most affordable flight options available from Illinois to Colorado. Find the lowest fares from popular airlines and budget airlines, with prices last updated on May 2, 2026.
This Cheapflightsfares deal was found by Cheapflights users on 5/1. 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.
Sat 6/68:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Tue 6/94:12 pm
DEN
- STL
Nonstop2h 11m
Frontier
Deal found 5/1![Frontier logo]()
$101
This Frontier deal was found by Cheapflights users on 4/30. 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.
Tue 5/268:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Sat 6/64:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/30![Frontier logo]()
$102
This Kiwi.com deal was found by Cheapflights users on 4/29. 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 5/206:51 pm
STL
- DEN
1 stop9h 34m
Frontier
Wed 5/274:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/29![Frontier logo]()
$106
This Cheapflightsfares deal was found by Cheapflights users on 4/30. 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.
Sat 5/238:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Wed 5/274:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/30![Frontier logo]()
$107
This Frontier deal was found by Cheapflights users on 4/30. 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.
Tue 5/268:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Thu 6/44:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/30![Frontier logo]()
$108
This Kiwi.com deal was found by Cheapflights users on 4/29. 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 5/268:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Thu 5/284:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/29![Frontier logo]()
$110
This Frontier deal was found by Cheapflights users on 5/1. 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.
Tue 6/28:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Wed 6/34:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 5/1![Frontier logo]()
$111
This Kiwi.com deal was found by Cheapflights users on 4/28. 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 5/268:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Tue 6/211:54 pm
DEN
- STL
1 stop8h 01m
Frontier
Deal found 4/28![Frontier logo]()
$113
This Kiwi.com deal was found by Cheapflights users on 4/29. 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.
Mon 5/258:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Wed 5/274:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/29![Frontier logo]()
$116
This Cheapflightsfares deal was found by Cheapflights users on 4/29. 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 5/276:51 pm
STL
- DEN
1 stop15h 47m
Frontier
Wed 6/34:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/29![Frontier logo]()
$117
This Frontier deal was found by Cheapflights users on 4/30. 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.
Tue 5/268:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Mon 6/112:34 pm
DEN
- STL
1 stop6h 37m
Frontier
Deal found 4/30![Frontier logo]()
$118
This Kiwi.com deal was found by Cheapflights users on 4/28. 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 6/107:04 pm
STL
- DEN
1 stop28h 57m
Frontier
Wed 6/174:12 pm
DEN
- STL
Nonstop2h 11m
Frontier
Deal found 4/28![Frontier logo]()
$119
Best flights from Illinois to ColoradoDiscover carefully curated flight deals from Illinois to Colorado that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated May 2, 2026.
Discover carefully curated flight deals from Illinois to Colorado that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated May 2, 2026.
This United Airlines deal was found by Cheapflights users on 4/27. 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.
Tue 5/265:10 am
STL
- DEN
Nonstop2h 22m
United Airlines
Wed 5/273:06 pm
DEN
- STL
1 stop5h 15m
United Airlines
Deal found 4/27![United Airlines logo]()
$211
This Southwest deal was found by Cheapflights users on 4/30. 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.
Fri 8/218:45 pm
MDW
- DEN
Nonstop2h 35m
Southwest
Tue 8/251:55 pm
DEN
- MDW
1 stop4h 30m
Southwest
Deal found 4/30![Southwest logo]()
$239
This Delta deal was found by Cheapflights users on 4/30. 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 9/231:15 pm
ORD
- DEN
1 stop8h 04m
Delta
Sat 9/2612:59 am
DEN
- ORD
1 stop6h 35m
Delta
Deal found 4/30![Delta logo]()
$253
This KAYAK deal was found by Cheapflights users on 4/29. 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 KAYAK is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 6/2210:00 am
ORD
- COS
Nonstop2h 56m
American Airlines
Wed 6/243:53 pm
COS
- ORD
1 stop7h 46m
American Airlines
Deal found 4/29![American Airlines logo]()
$411
This United Airlines deal was found by Cheapflights users on 5/1. 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.
Mon 5/255:00 am
ORD
- DEN
Nonstop2h 41m
United Airlines
Sat 5/306:00 am
DEN
- ORD
Nonstop2h 38m
United Airlines
Deal found 5/1![United Airlines logo]()
$221
This Southwest deal was found by Cheapflights users on 4/27. 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.
Mon 6/16:00 am
MDW
- DEN
Nonstop2h 40m
Southwest
Sat 6/135:15 am
DEN
- MDW
Nonstop2h 20m
Southwest
Deal found 4/27![Southwest logo]()
$243
This Southwest deal was found by Cheapflights users on 4/28. 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.
Wed 8/196:00 pm
MDW
- DEN
Nonstop2h 40m
Southwest
Thu 8/203:55 pm
DEN
- MDW
1 stop4h 35m
Southwest
Deal found 4/28![Southwest logo]()
$243
This Delta deal was found by Cheapflights users on 4/28. 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 7/13:22 pm
ORD
- DEN
1 stop6h 22m
Delta
Sun 7/55:45 am
DEN
- ORD
1 stop5h 51m
Delta
Deal found 4/28![Delta logo]()
$275
This Delta deal was found by Cheapflights users on 5/1. 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.
Thu 7/3012:41 pm
MDW
- DEN
1 stop9h 12m
Delta
Mon 8/312:40 am
DEN
- MDW
1 stop8h 23m
Delta
Deal found 5/1![Delta logo]()
$275
This Southwest deal was found by Cheapflights users on 4/30. 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.
Fri 5/293:45 pm
ORD
- DEN
1 stop6h 05m
Southwest
Wed 6/311:25 am
DEN
- ORD
Nonstop2h 35m
Southwest
Deal found 4/30![Southwest logo]()
$251
This United Airlines deal was found by Cheapflights users on 5/1. 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.
Sun 5/316:00 am
ORD
- DEN
Nonstop2h 41m
United Airlines
Sun 5/319:05 pm
DEN
- ORD
Nonstop2h 39m
United Airlines
Deal found 5/1![United Airlines logo]()
$285
This Delta deal was found by Cheapflights users on 4/28. 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.
Thu 5/217:01 pm
STL
- DEN
1 stop6h 32m
Delta
Mon 5/2512:56 am
DEN
- STL
1 stop6h 22m
Delta
Deal found 4/28![Delta logo]()
$275
This Southwest deal was found by Cheapflights users on 4/29. 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.
Fri 6/265:15 am
MDW
- DEN
Nonstop2h 35m
Southwest
Tue 6/307:40 am
DEN
- MDW
1 stop3h 45m
Southwest
Deal found 4/29![Southwest logo]()
$261
This Delta deal was found by Cheapflights users on 4/30. 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.
Fri 10/167:40 pm
ORD
- DEN
1 stop4h 19m
Delta
Thu 10/2212:55 am
DEN
- ORD
1 stop6h 05m
Delta
Deal found 4/30![Delta logo]()
$285
This Southwest deal was found by Cheapflights users on 4/30. 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 6/207:20 am
MDW
- DEN
Nonstop2h 35m
Southwest
Sun 6/288:55 pm
DEN
- MDW
Nonstop2h 20m
Southwest
Deal found 4/30![Southwest logo]()
$265
This United Airlines deal was found by Cheapflights users on 5/1. 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.
Fri 7/105:43 pm
PIA
- DEN
1 stop7h 05m
United Airlines
Wed 7/155:33 pm
DEN
- PIA
Nonstop2h 28m
United Airlines
Deal found 5/1![United Airlines logo]()
$334
This Delta deal was found by Cheapflights users on 5/1. 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.
Sat 8/153:50 pm
ORD
- DEN
1 stop5h 08m
Delta
Wed 8/1912:55 am
DEN
- ORD
1 stop6h 01m
Delta
Deal found 5/1![Delta logo]()
$285
This Southwest deal was found by Cheapflights users on 5/1. 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.
Fri 7/179:25 pm
MDW
- DEN
Nonstop2h 40m
Southwest
Mon 7/205:55 am
DEN
- MDW
Nonstop2h 25m
Southwest
Deal found 5/1![Southwest logo]()
$265
This Delta deal was found by Cheapflights users on 4/30. 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.
Fri 10/21:15 pm
ORD
- DEN
1 stop8h 04m
Delta
Sat 10/312:59 am
DEN
- ORD
1 stop8h 05m
Delta
Deal found 4/30![Delta logo]()
$285
This United Airlines deal was found by Cheapflights users on 4/30. 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 6/209:06 am
ORD
- COS
Nonstop3h 04m
United Airlines
Sun 6/285:44 am
COS
- ORD
Nonstop3h 01m
United Airlines
Deal found 4/30![United Airlines logo]()
$351
This Southwest deal was found by Cheapflights users on 4/28. 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.
Mon 7/275:15 am
MDW
- DEN
Nonstop2h 35m
Southwest
Fri 7/315:55 am
DEN
- MDW
Nonstop2h 25m
Southwest
Deal found 4/28![Southwest logo]()
$265
This Delta deal was found by Cheapflights users on 4/29. 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.
Mon 7/65:57 pm
ORD
- DEN
1 stop6h 39m
Delta
Sun 7/126:05 am
DEN
- ORD
1 stop5h 58m
Delta
Deal found 4/29![Delta logo]()
$285
This United Airlines deal was found by Cheapflights users on 4/29. 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.
Tue 6/98:52 am
ORD
- ASE
Nonstop3h 09m
United Airlines
Fri 6/123:25 pm
ASE
- ORD
1 stop6h 54m
United Airlines
Deal found 4/29![United Airlines logo]()
$353
This Southwest deal was found by Cheapflights users on 4/27. 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.
Wed 9/28:55 am
MDW
- DEN
1 stop5h 00m
Southwest
Mon 9/76:25 am
DEN
- MDW
1 stop4h 50m
Southwest
Deal found 4/27![Southwest logo]()
$270
This Delta deal was found by Cheapflights users on 4/29. 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.
Fri 9/111:15 pm
ORD
- DEN
1 stop8h 04m
Delta
Sat 9/1212:59 am
DEN
- ORD
1 stop6h 35m
Delta
Deal found 4/29![Delta logo]()
$285
This United Airlines deal was found by Cheapflights users on 4/28. 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.
Tue 7/215:00 am
ORD
- ASE
1 stop4h 46m
United Airlines
Tue 7/286:12 pm
ASE
- ORD
1 stop5h 32m
United Airlines
Deal found 4/28![United Airlines logo]()
$363
This Southwest deal was found by Cheapflights users on 4/28. 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.
Wed 7/154:30 pm
MDW
- DEN
1 stop5h 20m
Southwest
Wed 7/2210:15 am
DEN
- MDW
1 stop5h 35m
Southwest
Deal found 4/28![Southwest logo]()
$275
This American Airlines deal was found by Cheapflights users on 4/27. 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.
Fri 5/811:43 am
ORD
- EGE
1 stop8h 26m
American Airlines
Sun 5/178:00 am
EGE
- ORD
1 stop8h 44m
American Airlines
Deal found 4/27![American Airlines logo]()
$599
This Delta deal was found by Cheapflights users on 5/1. 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.
Fri 8/141:15 pm
ORD
- DEN
1 stop8h 04m
Delta
Sat 8/226:05 am
DEN
- ORD
1 stop7h 14m
Delta
Deal found 5/1![Delta logo]()
$285
This United Airlines deal was found by Cheapflights users on 4/27. 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 6/106:34 pm
MLI
- DEN
1 stop6h 03m
United Airlines
Wed 6/175:38 pm
DEN
- MLI
Nonstop2h 16m
United Airlines
Deal found 4/27![United Airlines logo]()
$365
Last-minute flights from Illinois to ColoradoDiscover last-minute flight deals from Illinois to Colorado. Data last updated May 2, 2026 and is based on user searches.
Discover last-minute flight deals from Illinois to Colorado. Data last updated May 2, 2026 and is based on user searches.
This Kiwi.com deal was found by Cheapflights users on 4/29. 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 5/206:51 pm
STL
- DEN
1 stop9h 34m
Frontier
Wed 5/274:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/29![Frontier logo]()
$106
This Cheapflightsfares deal was found by Cheapflights users on 4/30. 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.
Sat 5/238:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Wed 5/274:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/30![Frontier logo]()
$107
This Kiwi.com deal was found by Cheapflights users on 4/30. 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.
Mon 5/258:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Wed 6/34:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/30![Frontier logo]()
$116
This Frontier deal was found by Cheapflights users on 4/30. 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.
Tue 5/268:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Sat 6/64:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/30![Frontier logo]()
$102
This Frontier deal was found by Cheapflights users on 4/30. 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.
Tue 5/268:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Thu 6/44:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/30![Frontier logo]()
$108
This Kiwi.com deal was found by Cheapflights users on 4/29. 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 5/268:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Thu 5/284:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/29![Frontier logo]()
$110
This Kiwi.com deal was found by Cheapflights users on 4/28. 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 5/268:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Tue 6/211:54 pm
DEN
- STL
1 stop8h 01m
Frontier
Deal found 4/28![Frontier logo]()
$113
This Frontier deal was found by Cheapflights users on 4/30. 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.
Tue 5/268:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Mon 6/112:34 pm
DEN
- STL
1 stop6h 37m
Frontier
Deal found 4/30![Frontier logo]()
$118
This Cheapflightsfares deal was found by Cheapflights users on 4/29. 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 5/276:51 pm
STL
- DEN
1 stop15h 47m
Frontier
Wed 6/34:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/29![Frontier logo]()
$117
This Frontier deal was found by Cheapflights users on 5/1. 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.
Tue 6/28:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Wed 6/34:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 5/1![Frontier logo]()
$111
This Cheapflightsfares deal was found by Cheapflights users on 5/1. 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.
Sat 6/68:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Tue 6/94:12 pm
DEN
- STL
Nonstop2h 11m
Frontier
Deal found 5/1![Frontier logo]()
$101
This Kiwi.com deal was found by Cheapflights users on 4/28. 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 6/107:04 pm
STL
- DEN
1 stop28h 57m
Frontier
Wed 6/174:12 pm
DEN
- STL
Nonstop2h 11m
Frontier
Deal found 4/28![Frontier logo]()
$119
One-way flights from Illinois to ColoradoSearch for one-way flight options from Illinois to Colorado. Find affordable one-way fares based on user searches. Data last updated May 2, 2026.
Search for one-way flight options from Illinois to Colorado. Find affordable one-way fares based on user searches. Data last updated May 2, 2026.
This Kiwi.com deal was found by Cheapflights users on 4/30. 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 5/268:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/30![Frontier logo]()
$27
This Cheapflightsfares deal was found by Cheapflights users on 4/30. 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.
Tue 6/238:08 pm
STL
- DEN
Nonstop2h 36m
Frontier
Deal found 4/30![Frontier logo]()
$28
This Cheapflightsfares deal was found by Cheapflights users on 4/30. 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 8/178:08 pm
STL
- DEN
Nonstop2h 36m
Frontier
Deal found 4/30![Frontier logo]()
$54
This Cheapflightsfares deal was found by Cheapflights users on 4/27. 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.
Sun 8/3010:07 am
PIA
- DEN
Nonstop2h 19m
Allegiant Air
Deal found 4/27![Allegiant Air logo]()
$58
This Booking.com deal was found by Cheapflights users on 5/1. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 6/38:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 5/1![Frontier logo]()
$64
This Kiwi.com deal was found by Cheapflights users on 4/30. 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 5/288:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/30![Frontier logo]()
$73
This Cheapflightsfares deal was found by Cheapflights users on 4/30. 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 8/218:08 pm
STL
- DEN
Nonstop2h 36m
Frontier
Deal found 4/30![Frontier logo]()
$74
This Super.com deal was found by Cheapflights users on 4/27. 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.
Mon 5/184:19 pm
STL
- DEN
1 stop17h 05m
Frontier
Deal found 4/27![Frontier logo]()
$75
This Kiwi.com deal was found by Cheapflights users on 4/30. 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.
Mon 5/258:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/30![Frontier logo]()
$79
This eDestinos deal was found by Cheapflights users on 4/30. 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 eDestinos is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/159:18 pm
STL
- DEN
1 stop7h 07m
Frontier
Deal found 4/30![Frontier logo]()
$83
This Trip.com deal was found by Cheapflights users on 4/27. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/126:00 am
MDW
- DEN
1 stop9h 04m
Frontier
Deal found 4/27![Frontier logo]()
$92
This Kiwi.com deal was found by Cheapflights users on 4/29. 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 6/312:04 pm
MDW
- DEN
1 stop11h 20m
Frontier
Deal found 4/29![Frontier logo]()
$93
Find flight deals from Illinois to Colorado
Keep the following information in mind while searching for Illinois to Colorado flight deals. Data was last updated May 2, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $101 (Cheapflightsfares) |
One-way from | $27 (Kiwi.com) |
Popular in | March |
Cheapest in | September |
Average price | $230 |
Good round-trip deal | $220 or less |
Good one-way deal | $131 or less |
Cheapflights Fare Finder
Customize your flight search to find flights from Illinois to Colorado 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 May 2, 2026.
Use the filters below to find and compare flights from Illinois to Colorado that are best for you.
Fly from
Fly to
Route
Depart
Return
Cheapest round-trip
St. LouisDenver
STL - DEN
STLDEN
Lambert-St Louis
Tue 5/26
5:10 am-6:32 am
Nonstop2h 22m
Denver Intl
Wed 5/27
3:06 pm-9:21 pm
1 stop5h 15m
$211
ChicagoDenver
ORD - DEN
ORDDEN
Chicago O'Hare Intl
Mon 5/25
5:00 am-6:41 am
Nonstop2h 41m
Denver Intl
Sat 5/30
6:00 am-9:38 am
Nonstop2h 38m
$221
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Fri 8/21
8:45 pm-10:20 pm
Nonstop2h 35m
Denver Intl
Tue 8/25
1:55 pm-7:25 pm
1 stop4h 30m
$239
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Mon 6/1
6:00 am-7:40 am
Nonstop2h 40m
Denver Intl
Sat 6/13
5:15 am-8:35 am
Nonstop2h 20m
$243
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Wed 8/19
6:00 pm-7:40 pm
Nonstop2h 40m
Denver Intl
Thu 8/20
3:55 pm-9:30 pm
1 stop4h 35m
$243
ChicagoDenver
ORD - DEN
ORDDEN
Chicago O'Hare Intl
Fri 5/29
3:45 pm-8:50 pm
1 stop6h 05m
Denver Intl
Wed 6/3
11:25 am-3:00 pm
Nonstop2h 35m
$251
ChicagoDenver
ORD - DEN
ORDDEN
Chicago O'Hare Intl
Wed 9/23
1:15 pm-8:19 pm
1 stop8h 04m
Denver Intl
Sat 9/26
12:59 am-8:34 am
1 stop6h 35m
$253
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Fri 6/26
5:15 am-6:50 am
Nonstop2h 35m
Denver Intl
Tue 6/30
7:40 am-12:25 pm
1 stop3h 45m
$261
Quickest round-trip
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Sat 6/20
7:20 am-8:55 am
Nonstop2h 35m
Denver Intl
Sun 6/28
8:55 pm-12:15 am
Nonstop2h 20m
$265
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Fri 7/17
9:25 pm-11:05 pm
Nonstop2h 40m
Denver Intl
Mon 7/20
5:55 am-9:20 am
Nonstop2h 25m
$265
Showing 1-10 of 60 resultsSorted by cheapest first
Best time to book a flight from Illinois to Colorado
Have a flexible travel schedule? Discover the best time to fly to Colorado from Illinois with our price prediction graph.
STL-DEN
MDW-DEN
ORD-DEN
ORD-COS
PIA-DEN
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 Colorado
USIL-USCO
STL-DEN
MDW-DEN
ORD-DEN
ORD-COS
How far ahead should I book a flight from Illinois to Colorado?
Booking 84 days in advance of your planned departure date is, on average, the best time to get cheap flights from Illinois to Colorado. The general trend is that the closer you book to the departure date, the more expensive your flight will be.
What is the cheapest month to book a flight from Illinois to Colorado?
Currently, November is the cheapest month in which you can book a flight from Illinois to Colorado (average of $182). Flying from Illinois to Colorado in March is currently the most expensive (average of $328). 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 CO?
Find hourly flight availability from Illinois to Colorado. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated May 2, 2026.
It’s optimal to fly from Illinois to Colorado at noon. By choosing this option you can save up to 16% on the cost of your flight, compared to a flight in the evening.
What is the cheapest day to fly from Illinois to Colorado?
Use this chart to determine the cheapest time to fly round-trip from Illinois to Colorado. Price data was last updated on May 18, 2025.
Travelers seeking maximum savings on their Illinois to Colorado flight should consider departing on Saturday afternoons when fares are most often at their lowest. Monday mornings flights should be avoided if possible as fares are typically the most expensive at this time.
Weekly flight availability from Illinois to Colorado
Explore weekly flight availability from Illinois to Colorado. 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 May 2, 2026.
The most flights from USIL to USCO are scheduled on a Saturday (62 on average). You will have fewer flight options on Sunday, which is when the least amount of flights are scheduled (45 on average).
How much does it cost to fly round-trip from Illinois to Colorado?
Reviews of airlines servicing Colorado
Get insights into the airlines that provide service to Colorado. 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 Colorado. Reviews last updated May 2, 2026.
Read reviews from past customers who have flown Southwest,United Airlines, andAllegiant Air from Illinois to Colorado. You can also see how each airline compares in terms of entertainment options, comfort, food, crew/service, and boarding process.
Boarding
8.1
Entertainment
7.5
Overall
8.0
Food
7.0
Crew
8.6
Comfort
8.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Boarding
8.1
Entertainment
7.5
Overall
8.0
Food
7.0
Crew
8.6
Comfort
8.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Boarding
8.1
Entertainment
7.5
Overall
8.0
Food
7.0
Crew
8.6
Comfort
8.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Boarding
8.1
Entertainment
7.5
Overall
8.0
Food
7.0
Crew
8.6
Comfort
8.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Boarding
8.1
Entertainment
7.5
Overall
8.0
Food
7.0
Crew
8.6
Comfort
8.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Boarding
8.1
Entertainment
7.5
Overall
8.0
Food
7.0
Crew
8.6
Comfort
8.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Related info for your journey
Find useful and relevant information for your journey from Illinois to Colorado. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.
Browse thousands of different options on Cheapflights for your next trip
Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.
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Alternative routes for Illinois to Colorado
See prices for flight routes from nearby airports that may be better suited for you.
Complete your trip
Complete your trip to Colorado by adding a car rental and/or hotel reservation to your travel itinerary.
Search flights from Illinois to Colorado by cabin class
Find flights from Illinois to Colorado, based on your preferred cabin class, be it economy, premium economy, business, or first class.
Illinois and Colorado flights
Browse other Illinois and Colorado flight options. Last updated on May 2, 2026.
Popular flight searches
Check out other popular destinations found by fellow travelers in 2026
Find a return flight route from Colorado
Find the right flight back to Illinois after your stay in Colorado
Illinois to Colorado flights
Consider these flights traveling from Illinois to Colorado.
Top 6 airlines flying from Illinois to Colorado
Discover the top 6 airlines that operate flights from Illinois to Colorado. 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 May 2, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$53 | Average$168 | FlexibilityNo cancel fee | On-time88% | |
| Cheapest$68 | Average$167 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$145 | Average$223 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$151 | Average$312 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$152 | Average$395 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$160 | Average$400 | FlexibilityNo cancel fee | On-time69% |