$56+ Cheap flights from Colorado 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 9/26. Fares are subject to change and may not be available on all flights or dates of travel.
DEN — ORD
Sep 14 — Sep 211
Round-trip
1 adult, Economy
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Find cheap flights from Colorado to Illinois with Cheapflights
1. Tell us where you want to go
Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”2. Select your favorite providers
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Cheapest flights from Colorado to IllinoisExplore the most affordable flight options available from Colorado to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on August 15, 2026.
Explore the most affordable flight options available from Colorado to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on August 15, 2026.
This Booking.com deal was found by Cheapflights users on 8/10. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/2910:20 am -
Nonstop1h 59m
Sun 11/15:24 pm -
Nonstop2h 20m
Deal found 8/10![Allegiant Air logo]()
$90
This Gotogate deal was found by Cheapflights users on 8/11. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/272:17 pm -
Nonstop2h 07m
Sun 8/3010:07 am -
Nonstop2h 19m
Deal found 8/11![Allegiant Air logo]()
$152
This Kiwi.com deal was found by Cheapflights users on 8/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/258:55 pm -
Nonstop2h 28m
Mon 9/283:50 pm -
1 stop17h 02m
Deal found 8/14![Frontier logo]()
$160
This Kiwi.com deal was found by Cheapflights users on 8/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 10/118:55 pm -
Nonstop2h 29m
Wed 10/146:30 am -
Nonstop2h 49m
Deal found 8/14![Frontier logo]()
$161
This Kiwi.com deal was found by Cheapflights users on 8/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/188:55 pm -
Nonstop2h 28m
Wed 9/237:28 pm -
1 stop13h 36m
Deal found 8/15![Frontier logo]()
$162
This Frontier deal was found by Cheapflights users on 8/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/158:55 pm -
Nonstop2h 28m
Fri 9/256:30 am -
Nonstop2h 45m
Deal found 8/15![Frontier logo]()
$163
This Cheapflightsfares deal was found by Cheapflights users on 8/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/187:12 pm -
1 stop26h 47m
Sun 9/206:30 am -
Nonstop2h 45m
Deal found 8/13![Frontier logo]()
$164
This Frontier deal was found by Cheapflights users on 8/12. 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 10/1011:48 pm -
1 stop10h 10m
Tue 10/136:40 am -
1 stop8h 20m
Deal found 8/12![Frontier logo]()
$164
This United Airlines deal was found by Cheapflights users on 8/12. 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 10/106:10 pm -
Nonstop2h 42m
Tue 10/1310:00 pm -
Nonstop2h 53m
Deal found 8/12![United Airlines logo]()
$165
This Southwest deal was found by Cheapflights users on 8/12. 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 9/127:15 am -
Nonstop2h 20m
Mon 9/147:00 am -
Nonstop2h 30m
Deal found 8/12![Southwest logo]()
$165
This Frontier deal was found by Cheapflights users on 8/11. 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.
Sat 10/106:25 am -
Nonstop2h 36m
Tue 10/132:46 pm -
1 stop7h 55m
Deal found 8/11![Frontier logo]()
$166
This Frontier deal was found by Cheapflights users on 8/12. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/1611:48 pm -
1 stop7h 27m
Wed 10/2111:06 am -
Nonstop2h 54m
Deal found 8/12![Frontier logo]()
$167
Best flights from Colorado to IllinoisDiscover carefully curated flight deals from Colorado to Illinois that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated August 15, 2026.
Discover carefully curated flight deals from Colorado to Illinois that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated August 15, 2026.
This United Airlines deal was found by Cheapflights users on 8/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/236:18 pm -
Nonstop2h 42m
Sat 9/265:00 am -
Nonstop2h 39m
Deal found 8/13![United Airlines logo]()
$165
This Southwest deal was found by Cheapflights users on 8/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/118:25 pm -
Nonstop2h 25m
Tue 9/156:00 pm -
Nonstop2h 40m
Deal found 8/13![Southwest logo]()
$171
This Delta deal was found by Cheapflights users on 8/12. 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 10/76:10 am -
1 stop5h 49m
Wed 10/75:30 pm -
1 stop7h 14m
Deal found 8/12![Delta logo]()
$197
This KAYAK deal was found by Cheapflights users on 8/11. 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 KAYAK is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/217:16 am -
Nonstop2h 42m
Thu 9/245:00 am -
1 stop7h 27m
Deal found 8/11![American Airlines logo]()
$299
This Sun Country Air deal was found by Cheapflights users on 8/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Sun Country Air is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/257:21 pm -
1 stop11h 59m
Sun 11/297:35 pm -
1 stop23h 54m
Deal found 8/14![Sun Country Air logo]()
$315
This Southwest deal was found by Cheapflights users on 8/10. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/1011:05 am -
1 stop5h 05m
Mon 9/147:00 am -
Nonstop2h 30m
Deal found 8/10![Southwest logo]()
$175
This United Airlines deal was found by Cheapflights users on 8/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/91:27 pm -
Nonstop2h 07m
Thu 9/104:40 pm -
Nonstop2h 30m
Deal found 8/14![United Airlines logo]()
$177
This Southwest deal was found by Cheapflights users on 8/10. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/148:25 pm -
Nonstop2h 25m
Wed 9/161:55 pm -
2 stops7h 00m
Deal found 8/10![Southwest logo]()
$176
This Delta deal was found by Cheapflights users on 8/12. 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 9/196:30 am -
1 stop5h 09m
Tue 9/227:13 pm -
1 stop5h 22m
Deal found 8/12![Delta logo]()
$197
This United Airlines deal was found by Cheapflights users on 8/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/187:10 pm -
Nonstop2h 35m
Mon 9/215:55 am -
Nonstop2h 39m
Deal found 8/13![United Airlines logo]()
$187
This Southwest deal was found by Cheapflights users on 8/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/267:35 am -
Nonstop2h 00m
Mon 9/286:05 pm -
Nonstop2h 15m
Deal found 8/14![Southwest logo]()
$177
This Southwest deal was found by Cheapflights users on 8/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/288:25 pm -
Nonstop2h 25m
Thu 10/19:55 am -
1 stop5h 35m
Deal found 8/13![Southwest logo]()
$181
This United Airlines deal was found by Cheapflights users on 8/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/175:30 am -
1 stop5h 27m
Mon 9/219:00 am -
Nonstop2h 31m
Deal found 8/14![United Airlines logo]()
$206
This Delta deal was found by Cheapflights users on 8/11. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 11/71:26 pm -
1 stop8h 07m
Tue 11/101:00 pm -
1 stop8h 27m
Deal found 8/11![Delta logo]()
$241
This Southwest deal was found by Cheapflights users on 8/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/107:00 am -
Nonstop2h 00m
Tue 9/152:50 pm -
1 stop3h 30m
Deal found 8/15![Southwest logo]()
$183
This United Airlines deal was found by Cheapflights users on 8/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/198:35 am -
Nonstop2h 44m
Sat 9/197:50 pm -
Nonstop2h 54m
Deal found 8/14![United Airlines logo]()
$213
This Delta deal was found by Cheapflights users on 8/11. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 11/71:26 pm -
1 stop6h 26m
Tue 11/101:30 pm -
1 stop7h 57m
Deal found 8/11![Delta logo]()
$241
This KAYAK deal was found by Cheapflights users on 8/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure KAYAK is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/215:01 am -
Nonstop2h 49m
Wed 9/2310:55 am -
Nonstop2h 53m
Deal found 8/13![American Airlines logo]()
$304
This Southwest deal was found by Cheapflights users on 8/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/126:00 am -
Nonstop2h 20m
Sat 9/196:00 pm -
Nonstop2h 45m
Deal found 8/13![Southwest logo]()
$189
This Delta deal was found by Cheapflights users on 8/11. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 10/186:10 am -
1 stop5h 49m
Sat 10/2412:29 pm -
1 stop4h 20m
Deal found 8/11![Delta logo]()
$246
This American Airlines deal was found by Cheapflights users on 8/10. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/35:06 am -
1 stop4h 56m
Sun 9/66:00 am -
2 stops10h 29m
Deal found 8/10![American Airlines logo]()
$304
This Southwest deal was found by Cheapflights users on 8/10. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/111:15 am -
1 stop3h 45m
Sat 9/126:50 am -
Nonstop2h 30m
Deal found 8/10![Southwest logo]()
$201
This Delta deal was found by Cheapflights users on 8/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/91:25 pm -
1 stop6h 31m
Tue 9/158:55 am -
2 stops12h 01m
Deal found 8/13![Delta logo]()
$246
This American Airlines deal was found by Cheapflights users on 8/12. 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 10/87:18 pm -
1 stop8h 42m
Mon 10/125:00 am -
1 stop7h 14m
Deal found 8/12![American Airlines logo]()
$318
This United Airlines deal was found by Cheapflights users on 8/11. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/85:32 pm -
Nonstop2h 06m
Tue 9/159:43 am -
1 stop6h 34m
Deal found 8/11![United Airlines logo]()
$266
This Delta deal was found by Cheapflights users on 8/12. 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 11/136:05 am -
1 stop6h 54m
Sun 11/156:30 am -
1 stop6h 41m
Deal found 8/12![Delta logo]()
$262
This Southwest deal was found by Cheapflights users on 8/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/2011:00 am -
1 stop4h 05m
Thu 10/229:20 pm -
Nonstop2h 40m
Deal found 8/14![Southwest logo]()
$219
This United Airlines deal was found by Cheapflights users on 8/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/52:50 pm -
Nonstop2h 42m
Mon 9/75:00 am -
Nonstop2h 39m
Deal found 8/14![United Airlines logo]()
$274
This American Airlines deal was found by Cheapflights users on 8/10. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/2812:40 pm -
1 stop8h 33m
Mon 8/315:00 am -
1 stop7h 14m
Deal found 8/10![American Airlines logo]()
$343
This Delta deal was found by Cheapflights users on 8/10. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/234:18 pm -
1 stop4h 18m
Mon 10/268:29 am -
1 stop7h 38m
Deal found 8/10![Delta logo]()
$270
Last-minute flights from Colorado to IllinoisDiscover last-minute flight deals from Colorado to Illinois. Data last updated August 15, 2026 and is based on user searches.
Discover last-minute flight deals from Colorado to Illinois. Data last updated August 15, 2026 and is based on user searches.
This Gotogate deal was found by Cheapflights users on 8/11. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/272:17 pm -
Nonstop2h 07m
Sun 8/3010:07 am -
Nonstop2h 19m
Deal found 8/11![Allegiant Air logo]()
$152
This Kiwi.com deal was found by Cheapflights users on 8/11. 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.
Tue 9/19:55 am -
Nonstop2h 41m
Fri 9/42:41 pm -
Nonstop3h 04m
Deal found 8/11![Frontier logo]()
$167
This Frontier deal was found by Cheapflights users on 8/11. 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 9/29:55 am -
Nonstop2h 41m
Thu 9/37:05 am -
1 stop7h 56m
Deal found 8/11![Frontier logo]()
$166
This Frontier deal was found by Cheapflights users on 8/11. 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 9/210:43 am -
1 stop8h 25m
Sun 9/62:41 pm -
Nonstop3h 04m
Deal found 8/11![Frontier logo]()
$168
This Priceline deal was found by Cheapflights users on 8/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/1010:44 am -
1 stop6h 02m
Thu 9/1712:54 pm -
1 stop9h 55m
Deal found 8/13![Frontier logo]()
$164
This Kiwi.com deal was found by Cheapflights users on 8/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/1110:44 am -
1 stop6h 07m
Tue 9/156:25 am -
1 stop15h 38m
Deal found 8/13![Frontier logo]()
$168
This Southwest deal was found by Cheapflights users on 8/12. 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 9/127:15 am -
Nonstop2h 20m
Mon 9/147:00 am -
Nonstop2h 30m
Deal found 8/12![Southwest logo]()
$165
This Frontier deal was found by Cheapflights users on 8/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/158:55 pm -
Nonstop2h 28m
Fri 9/256:30 am -
Nonstop2h 45m
Deal found 8/15![Frontier logo]()
$163
This Kiwi.com deal was found by Cheapflights users on 8/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/188:55 pm -
Nonstop2h 28m
Wed 9/237:28 pm -
1 stop13h 36m
Deal found 8/15![Frontier logo]()
$162
This Cheapflightsfares deal was found by Cheapflights users on 8/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/187:12 pm -
1 stop26h 47m
Sun 9/206:30 am -
Nonstop2h 45m
Deal found 8/13![Frontier logo]()
$164
This United Airlines deal was found by Cheapflights users on 8/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/236:18 pm -
Nonstop2h 42m
Sat 9/265:00 am -
Nonstop2h 39m
Deal found 8/13![United Airlines logo]()
$165
This Kiwi.com deal was found by Cheapflights users on 8/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/258:55 pm -
Nonstop2h 28m
Mon 9/283:50 pm -
1 stop17h 02m
Deal found 8/14![Frontier logo]()
$160
One-way flights from Colorado to IllinoisSearch for one-way flight options from Colorado to Illinois. Find affordable one-way fares based on user searches. Data last updated August 15, 2026.
Search for one-way flight options from Colorado to Illinois. Find affordable one-way fares based on user searches. Data last updated August 15, 2026.
This Super.com deal was found by Cheapflights users on 8/12. 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.
Sat 9/264:12 pm -
Nonstop2h 05m
Deal found 8/12![Frontier logo]()
$56
This Expedia deal was found by Cheapflights users on 8/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/94:12 pm -
Nonstop2h 05m
Deal found 8/13![Frontier logo]()
$57
This Kiwi.com deal was found by Cheapflights users on 8/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 9/64:00 pm -
Nonstop2h 13m
Deal found 8/13![Frontier logo]()
$59
This Cheapflightsfares deal was found by Cheapflights users on 8/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/254:12 pm -
Nonstop2h 05m
Deal found 8/14![Frontier logo]()
$62
This Cheapflightsfares deal was found by Cheapflights users on 8/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/314:00 pm -
Nonstop2h 13m
Deal found 8/14![Frontier logo]()
$63
This Trip.com deal was found by Cheapflights users on 8/11. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/46:30 am -
1 stop26h 10m
Deal found 8/11![Frontier logo]()
$64
This Kiwi.com deal was found by Cheapflights users on 8/12. 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 11/1110:56 am -
1 stop21h 44m
Deal found 8/12![Frontier logo]()
$65
This Kiwi.com deal was found by Cheapflights users on 8/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/114:12 pm -
Nonstop2h 05m
Deal found 8/15![Frontier logo]()
$71
This Super.com deal was found by Cheapflights users on 8/12. 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.
Tue 9/110:09 am -
1 stop5h 22m
Deal found 8/12![Frontier logo]()
$72
This Jetabroad deal was found by Cheapflights users on 8/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Jetabroad is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/102:16 pm -
Nonstop2h 03m
Deal found 8/14![Allegiant Air logo]()
$79
This Southwest deal was found by Cheapflights users on 8/12. 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 9/111:15 pm -
Nonstop2h 20m
Deal found 8/12![Southwest logo]()
$101
This Mytrip deal was found by Cheapflights users on 8/11. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/272:17 pm -
Nonstop2h 07m
Deal found 8/11![Allegiant Air logo]()
$102
Find flight deals from Colorado to Illinois
Keep the following information in mind while searching for Colorado to Illinois flight deals. Data was last updated August 15, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $120 (Cheapflightsfares) |
One-way from | $56 (Super.com) |
Popular in | July |
Cheapest in | January |
Average price | $242 |
Good round-trip deal | $267 or less |
Good one-way deal | $140 or less |
Cheapflights Fare Finder
Customize your flight search to find flights from Colorado 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 August 15, 2026.
Use the filters below to find and compare flights from Colorado to Illinois that are best for you.
Fly from
Fly to
Route
Depart
Return
Cheapest round-trip
DenverChicago
DEN Denver Intl - ORD Chicago O'Hare Intl
DENORD
Denver Intl
Wed 9/23
6:18 pm-10:00 pm
Nonstop2h 42m
Chicago O'Hare Intl
Sat 9/26
5:00 am-6:39 am
Nonstop2h 39m
$165
DenverChicago
DEN Denver Intl - MDW Chicago Midway
DENMDW
Denver Intl
Fri 9/11
8:25 pm-11:50 pm
Nonstop2h 25m
Chicago Midway
Tue 9/15
6:00 pm-7:40 pm
Nonstop2h 40m
$171
DenverChicago
DEN Denver Intl - MDW Chicago Midway
DENMDW
Denver Intl
Thu 9/10
11:05 am-5:10 pm
1 stop5h 05m
Chicago Midway
Mon 9/14
7:00 am-8:30 am
Nonstop2h 30m
$175
DenverChicago
DEN Denver Intl - MDW Chicago Midway
DENMDW
Denver Intl
Mon 9/14
8:25 pm-11:50 pm
Nonstop2h 25m
Chicago Midway
Wed 9/16
1:55 pm-7:55 pm
2 stops7h 00m
$176
DenverSt. Louis
DEN Denver Intl - STL Lambert-St Louis
DENSTL
Denver Intl
Wed 9/9
1:27 pm-4:34 pm
Nonstop2h 07m
Lambert-St Louis
Thu 9/10
4:40 pm-6:10 pm
Nonstop2h 30m
$177
Quickest round-trip
DenverSt. Louis
DEN Denver Intl - STL Lambert-St Louis
DENSTL
Denver Intl
Sat 9/26
7:35 am-10:35 am
Nonstop2h 00m
Lambert-St Louis
Mon 9/28
6:05 pm-7:20 pm
Nonstop2h 15m
$177
DenverChicago
DEN Denver Intl - MDW Chicago Midway
DENMDW
Denver Intl
Mon 9/28
8:25 pm-11:50 pm
Nonstop2h 25m
Chicago Midway
Thu 10/1
9:55 am-2:30 pm
1 stop5h 35m
$181
DenverSt. Louis
DEN Denver Intl - STL Lambert-St Louis
DENSTL
Denver Intl
Thu 9/10
7:00 am-10:00 am
Nonstop2h 00m
Lambert-St Louis
Tue 9/15
2:50 pm-5:20 pm
1 stop3h 30m
$183
DenverChicago
DEN Denver Intl - ORD Chicago O'Hare Intl
DENORD
Denver Intl
Fri 9/18
7:10 pm-10:45 pm
Nonstop2h 35m
Chicago O'Hare Intl
Mon 9/21
5:55 am-7:34 am
Nonstop2h 39m
$187
DenverChicago
DEN Denver Intl - MDW Chicago Midway
DENMDW
Denver Intl
Sat 9/12
6:00 am-9:20 am
Nonstop2h 20m
Chicago Midway
Sat 9/19
6:00 pm-7:45 pm
Nonstop2h 45m
$189
Showing 1-10 of 60 resultsSorted by cheapest first
Best time to book a flight from Colorado to Illinois
Have a flexible travel schedule? Discover the best time to fly to Illinois from Colorado with our price prediction graph.
DEN-STL
DEN-PIA
COS-MDW
DEN-ORD
DEN-MDW
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 Colorado to Illinois
USCO-USIL
DEN-STL
DEN-PIA
COS-MDW
DEN-ORD
What is the cheapest month to book a flight from Colorado to Illinois?
Currently, January is the cheapest month in which you can book a flight from Colorado to Illinois (average of $247). Flying from Colorado to Illinois in July is currently the most expensive (average of $356). 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 CO to IL?
Find hourly flight availability from Colorado 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 August 15, 2026.
A simple way to save on the total cost of your ticket is to fly from Colorado to Illinois in the evening. If you’re flexible enough to do this you can expect to save up to 36% on your trip compared to booking a flight at noon.
Weekly flight availability from Colorado to Illinois
Explore weekly flight availability from Colorado 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 August 15, 2026.
The most flights from USCO to USIL are scheduled on a Friday (74 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (27 on average).
How much does it cost to fly round-trip from Colorado to Illinois?
Airfare is below average for this route at the moment.
Colorado to Illinois flights typically cost between $217 and $386 in September.The cheapest round-trip price found within the last 5 days was $160 on Frontier (Sep 25-Sep 28).
How far ahead should I book a flight from Colorado to Illinois?
To ensure you get the cheapest price possible for a flight from Colorado to Illinois, you should look to book at least 78 days in advance of your intended travel date. The price of your flight may increase if you delay and leave booking until a week or so before departure.
What is the cheapest day to fly from Colorado to Illinois?
Use this chart to determine the cheapest time to fly round-trip from Colorado to Illinois. Price data was last updated on August 8, 2026.
Travelers seeking maximum savings on their Colorado to Illinois flight should consider departing on Friday at noon when fares are most often at their lowest. Saturday at noon flights should be avoided if possible as fares are typically the most expensive at this time.
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 August 15, 2026.
Read reviews from past customers who have flown Southwest,United Airlines, andAllegiant Air from Colorado to Illinois. You can also see how each airline compares in terms of entertainment options, comfort, food, crew/service, and boarding process.
Boarding
8.1
Crew
8.6
Food
7.0
Overall
8.0
Entertainment
7.5
Comfort
8.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Boarding
8.1
Crew
8.6
Food
7.0
Overall
8.0
Entertainment
7.5
Comfort
8.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Boarding
8.1
Crew
8.6
Food
7.0
Overall
8.0
Entertainment
7.5
Comfort
8.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Boarding
8.1
Crew
8.6
Food
7.0
Overall
8.0
Entertainment
7.5
Comfort
8.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Boarding
8.1
Crew
8.6
Food
7.0
Overall
8.0
Entertainment
7.5
Comfort
8.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Boarding
8.1
Crew
8.6
Food
7.0
Overall
8.0
Entertainment
7.5
Comfort
8.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Related info for your journey
Find useful and relevant information for your journey from Colorado to Illinois. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.
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Alternative routes for Colorado to Illinois
See prices for flight routes from nearby airports that may be better suited for you.
Complete your trip
Complete your trip to Illinois by adding a car rental and/or hotel reservation to your travel itinerary.
Search flights from Colorado to Illinois by cabin class
Find flights from Colorado to Illinois, based on your preferred cabin class, be it economy, premium economy, business, or first class.
Colorado and Illinois flights
Browse other Colorado and Illinois flight options. Last updated on August 15, 2026.
Popular flight searches
Check out other popular destinations found by fellow travelers in 2026
Find a return flight route from Illinois
Find the right flight back to Colorado after your stay in Illinois
Colorado to Illinois flights
Consider these flights traveling from Colorado to Illinois.
Top 6 airlines flying from Colorado to Illinois
Discover the top 6 airlines that operate flights from Colorado 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 August 15, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$79 | Average$193 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$91 | Average$209 | FlexibilityNo cancel fee | On-time88% | |
| Cheapest$126 | Average$281 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$170 | Average$435 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$170 | Average$344 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$181 | Average$445 | FlexibilityNo cancel fee | On-time69% |