$91+ 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 8/24. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — DEN
Aug 28 — Sep 41
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 July 29, 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 July 29, 2026.
This Kiwi.com deal was found by Cheapflights users on 7/27. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/246:17 pm
STL
- DEN
1 stop16h 02m
Frontier
Mon 8/314:00 pm
DEN
- STL
Nonstop2h 13m
Frontier
Deal found 7/27![Frontier logo]()
$135
This Kiwi.com deal was found by Cheapflights users on 7/28. 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.
Sat 10/248:10 pm
STL
- DEN
Nonstop2h 39m
Frontier
Sat 10/3111:59 pm
DEN
- STL
1 stop9h 41m
Frontier
Deal found 7/28![Frontier logo]()
$139
This Kiwi.com deal was found by Cheapflights users on 7/27. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/277:58 pm
STL
- DEN
Nonstop2h 27m
Frontier
Sat 8/2911:59 pm
DEN
- STL
1 stop16h 23m
Frontier
Deal found 7/27![Frontier logo]()
$140
This Kiwi.com deal was found by Cheapflights users on 7/27. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/910:35 am
STL
- DEN
1 stop23h 56m
Frontier
Thu 10/154:12 pm
DEN
- STL
Nonstop2h 03m
Frontier
Deal found 7/27![Frontier logo]()
$141
This Kiwi.com deal was found by Cheapflights users on 7/26. 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 11/610:35 am
STL
- DEN
1 stop24h 26m
Frontier
Thu 11/124:12 pm
DEN
- STL
Nonstop2h 03m
Frontier
Deal found 7/26![Frontier logo]()
$144
This Kiwi.com deal was found by Cheapflights users on 7/28. 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.
Fri 9/46:17 pm
STL
- DEN
1 stop16h 02m
Frontier
Sun 9/64:00 pm
DEN
- STL
Nonstop2h 13m
Frontier
Deal found 7/28![Frontier logo]()
$145
This Kiwi.com deal was found by Cheapflights users on 7/27. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/1410:35 am
STL
- DEN
1 stop12h 58m
Frontier
Mon 10/194:12 pm
DEN
- STL
Nonstop2h 03m
Frontier
Deal found 7/27![Frontier logo]()
$146
This Kiwi.com deal was found by Cheapflights users on 7/27. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/52:29 pm
STL
- DEN
2 stops22h 41m
Frontier
Sat 10/104:12 pm
DEN
- STL
Nonstop2h 03m
Frontier
Deal found 7/27![Frontier logo]()
$147
This Cheapflightsfares deal was found by Cheapflights users on 7/25. 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 9/188:10 pm
STL
- DEN
Nonstop2h 29m
Frontier
Sat 9/194:12 pm
DEN
- STL
Nonstop2h 05m
Frontier
Deal found 7/25![Frontier logo]()
$150
This Kiwi.com deal was found by Cheapflights users on 7/28. 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.
Fri 9/118:10 pm
STL
- DEN
Nonstop2h 29m
Frontier
Tue 9/157:10 pm
DEN
- STL
1 stop17h 00m
Frontier
Deal found 7/28![Frontier logo]()
$151
This Frontier deal was found by Cheapflights users on 7/26. 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 10/238:10 pm
STL
- DEN
Nonstop2h 39m
Frontier
Mon 10/264:12 pm
DEN
- STL
Nonstop2h 03m
Frontier
Deal found 7/26![Frontier logo]()
$152
This Kiwi.com deal was found by Cheapflights users on 7/28. 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.
Fri 8/212:41 pm
ORD
- DEN
Nonstop3h 04m
Frontier
Mon 8/249:55 am
DEN
- ORD
Nonstop2h 41m
Frontier
Deal found 7/28![Frontier logo]()
$157
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 July 29, 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 July 29, 2026.
This Southwest deal was found by Cheapflights users on 7/28. 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.
Tue 8/1812:20 pm
STL
- DEN
Nonstop2h 15m
Southwest
Sat 8/227:35 am
DEN
- STL
Nonstop2h 00m
Southwest
Deal found 7/28![Southwest logo]()
$172
This United Airlines deal was found by Cheapflights users on 7/25. 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 8/156:00 am
ORD
- DEN
Nonstop2h 39m
United Airlines
Thu 8/205:47 pm
DEN
- ORD
Nonstop2h 42m
United Airlines
Deal found 7/25![United Airlines logo]()
$213
This Delta deal was found by Cheapflights users on 7/25. 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 8/266:59 am
ORD
- DEN
1 stop7h 46m
Delta
Sat 8/296:05 am
DEN
- ORD
1 stop6h 45m
Delta
Deal found 7/25![Delta logo]()
$233
This American Airlines deal was found by Cheapflights users on 7/26. 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.
Wed 9/95:00 am
ORD
- MTJ
1 stop5h 41m
American Airlines
Wed 9/162:21 pm
MTJ
- ORD
1 stop5h 48m
American Airlines
Deal found 7/26![American Airlines logo]()
$319
This Southwest deal was found by Cheapflights users on 7/27. 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 8/178:45 pm
STL
- DEN
Nonstop2h 15m
Southwest
Sat 8/227:35 am
DEN
- STL
Nonstop2h 00m
Southwest
Deal found 7/27![Southwest logo]()
$187
This United Airlines deal was found by Cheapflights users on 7/24. 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 9/35:00 am
ORD
- DEN
Nonstop2h 39m
United Airlines
Sun 9/66:18 pm
DEN
- ORD
Nonstop2h 42m
United Airlines
Deal found 7/24![United Airlines logo]()
$214
This Kiwi.com deal was found by Cheapflights users on 7/28. 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 8/192:41 pm
ORD
- GJT
2 stops22h 32m
Multiple Airlines
Sun 8/231:23 pm
GJT
- ORD
1 stop28h 39m
Multiple Airlines
Deal found 7/28![Multiple Airlines logo]()
$434
This Southwest deal was found by Cheapflights users on 7/23. 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 8/225:05 pm
MDW
- DEN
Nonstop2h 40m
Southwest
Sat 8/297:15 am
DEN
- MDW
Nonstop2h 20m
Southwest
Deal found 7/23![Southwest logo]()
$205
This Delta deal was found by Cheapflights users on 7/28. 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 8/2611:22 am
ORD
- DEN
1 stop7h 01m
Delta
Wed 9/24:00 pm
DEN
- ORD
1 stop4h 47m
Delta
Deal found 7/28![Delta logo]()
$233
This Southwest deal was found by Cheapflights users on 7/23. 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 8/296:50 am
MDW
- DEN
Nonstop2h 30m
Southwest
Mon 8/316:30 pm
DEN
- MDW
Nonstop2h 30m
Southwest
Deal found 7/23![Southwest logo]()
$205
This United Airlines deal was found by Cheapflights users on 7/28. 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.
Thu 9/35:00 am
ORD
- DEN
Nonstop2h 39m
United Airlines
Mon 9/76:00 am
DEN
- ORD
Nonstop2h 43m
United Airlines
Deal found 7/28![United Airlines logo]()
$227
This Delta deal was found by Cheapflights users on 7/28. 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 8/196:42 pm
MDW
- DEN
1 stop5h 06m
Delta
Tue 8/256:00 am
DEN
- MDW
1 stop6h 10m
Delta
Deal found 7/28![Delta logo]()
$233
This Southwest deal was found by Cheapflights users on 7/28. 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.
Thu 8/273:45 pm
STL
- DEN
1 stop5h 15m
Southwest
Mon 8/3111:10 am
DEN
- STL
1 stop5h 55m
Southwest
Deal found 7/28![Southwest logo]()
$207
This Delta deal was found by Cheapflights users on 7/28. 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.
Sun 9/69:24 am
MDW
- DEN
1 stop4h 53m
Delta
Tue 9/86:15 am
DEN
- MDW
1 stop6h 05m
Delta
Deal found 7/28![Delta logo]()
$234
This United Airlines deal was found by Cheapflights users on 7/24. 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 10/95:00 am
ORD
- DEN
Nonstop2h 39m
United Airlines
Tue 10/136:10 pm
DEN
- ORD
Nonstop2h 41m
United Airlines
Deal found 7/24![United Airlines logo]()
$244
This Southwest deal was found by Cheapflights users on 7/24. 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 8/156:00 pm
MDW
- DEN
Nonstop2h 40m
Southwest
Wed 8/197:25 pm
DEN
- MDW
Nonstop2h 25m
Southwest
Deal found 7/24![Southwest logo]()
$213
This United Airlines deal was found by Cheapflights users on 7/26. 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 9/45:00 am
ORD
- DEN
Nonstop2h 39m
United Airlines
Mon 9/76:00 am
DEN
- ORD
Nonstop2h 43m
United Airlines
Deal found 7/26![United Airlines logo]()
$249
This Delta deal was found by Cheapflights users on 7/27. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/16:00 am
ORD
- DEN
1 stop7h 08m
Delta
Thu 9/312:59 am
DEN
- ORD
1 stop5h 57m
Delta
Deal found 7/27![Delta logo]()
$255
This Southwest deal was found by Cheapflights users on 7/23. 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 8/191:55 pm
MDW
- DEN
2 stops6h 55m
Southwest
Thu 8/273:15 pm
DEN
- MDW
1 stop3h 30m
Southwest
Deal found 7/23![Southwest logo]()
$221
This Delta deal was found by Cheapflights users on 7/27. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/227:05 am
ORD
- DEN
1 stop7h 52m
Delta
Sun 9/276:30 am
DEN
- ORD
1 stop5h 29m
Delta
Deal found 7/27![Delta logo]()
$264
This American Airlines deal was found by Cheapflights users on 7/28. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/1710:56 am
ORD
- COS
Nonstop2h 51m
American Airlines
Fri 8/2110:12 am
COS
- ORD
1 stop8h 30m
American Airlines
Deal found 7/28![American Airlines logo]()
$387
This United Airlines deal was found by Cheapflights users on 7/28. 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.
Sat 8/294:40 pm
STL
- DEN
Nonstop2h 30m
United Airlines
Mon 8/315:35 pm
DEN
- STL
Nonstop2h 11m
United Airlines
Deal found 7/28![United Airlines logo]()
$267
This Southwest deal was found by Cheapflights users on 7/27. 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.
Tue 10/271:05 pm
MDW
- DEN
1 stop4h 50m
Southwest
Tue 11/32:20 pm
DEN
- MDW
1 stop4h 15m
Southwest
Deal found 7/27![Southwest logo]()
$224
This United Airlines deal was found by Cheapflights users on 7/26. 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 11/114:39 pm
STL
- DEN
Nonstop2h 31m
United Airlines
Sat 11/141:55 pm
DEN
- STL
Nonstop2h 02m
United Airlines
Deal found 7/26![United Airlines logo]()
$267
This Southwest deal was found by Cheapflights users on 7/24. 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 9/1010:35 am
MDW
- DEN
1 stop5h 10m
Southwest
Sat 9/1211:10 am
DEN
- MDW
1 stop5h 00m
Southwest
Deal found 7/24![Southwest logo]()
$228
This Delta deal was found by Cheapflights users on 7/27. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/185:10 pm
ORD
- DEN
1 stop5h 22m
Delta
Sun 9/2012:55 am
DEN
- ORD
1 stop6h 01m
Delta
Deal found 7/27![Delta logo]()
$277
This United Airlines deal was found by Cheapflights users on 7/24. 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 10/271:40 pm
STL
- DEN
Nonstop2h 29m
United Airlines
Fri 10/305:52 pm
DEN
- STL
Nonstop2h 07m
United Airlines
Deal found 7/24![United Airlines logo]()
$272
This Southwest deal was found by Cheapflights users on 7/27. 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.
Sat 10/246:35 am
MDW
- DEN
1 stop5h 00m
Southwest
Wed 10/2810:45 am
DEN
- MDW
2 stops5h 05m
Southwest
Deal found 7/27![Southwest logo]()
$234
This Delta deal was found by Cheapflights users on 7/25. 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 8/271:25 pm
MDW
- COS
2 stops9h 13m
Delta
Tue 9/16:00 am
COS
- MDW
2 stops9h 59m
Delta
Deal found 7/25![Delta logo]()
$284
This United Airlines deal was found by Cheapflights users on 7/23. 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 8/291:36 pm
STL
- DEN
Nonstop2h 24m
United Airlines
Tue 9/16:00 am
DEN
- STL
1 stop7h 28m
United Airlines
Deal found 7/23![United Airlines logo]()
$277
Last-minute flights from Illinois to ColoradoDiscover last-minute flight deals from Illinois to Colorado. Data last updated July 29, 2026 and is based on user searches.
Discover last-minute flight deals from Illinois to Colorado. Data last updated July 29, 2026 and is based on user searches.
This Super.com deal was found by Cheapflights users on 7/26. 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 8/159:57 pm
ORD
- DEN
Nonstop3h 00m
Frontier
Tue 8/189:55 am
DEN
- ORD
Nonstop2h 41m
Frontier
Deal found 7/26![Frontier logo]()
$161
This Cheapflightsfares deal was found by Cheapflights users on 7/27. 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.
Mon 8/178:08 pm
STL
- DEN
Nonstop2h 36m
Frontier
Fri 8/214:00 pm
DEN
- STL
Nonstop2h 13m
Frontier
Deal found 7/27![Frontier logo]()
$150
This Kiwi.com deal was found by Cheapflights users on 7/24. 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 8/178:08 pm
STL
- DEN
Nonstop2h 36m
Frontier
Wed 8/197:00 am
DEN
- STL
2 stops33h 22m
Frontier
Deal found 7/24![Frontier logo]()
$152
This Frontier deal was found by Cheapflights users on 7/26. 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.
Mon 8/179:57 pm
ORD
- DEN
Nonstop3h 00m
Frontier
Fri 8/219:55 am
DEN
- ORD
Nonstop2h 41m
Frontier
Deal found 7/26![Frontier logo]()
$160
This Kiwi.com deal was found by Cheapflights users on 7/28. 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 8/182:41 pm
ORD
- DEN
Nonstop3h 04m
Frontier
Wed 8/267:00 am
DEN
- ORD
1 stop7h 59m
Frontier
Deal found 7/28![Frontier logo]()
$159
This Cheapflightsfares deal was found by Cheapflights users on 7/28. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/207:58 pm
STL
- DEN
Nonstop2h 27m
Frontier
Sun 8/234:00 pm
DEN
- STL
Nonstop2h 13m
Frontier
Deal found 7/28![Frontier logo]()
$146
This Kiwi.com deal was found by Cheapflights users on 7/28. 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.
Fri 8/212:41 pm
ORD
- DEN
Nonstop3h 04m
Frontier
Mon 8/249:55 am
DEN
- ORD
Nonstop2h 41m
Frontier
Deal found 7/28![Frontier logo]()
$157
This Kiwi.com deal was found by Cheapflights users on 7/27. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/246:17 pm
STL
- DEN
1 stop16h 02m
Frontier
Mon 8/314:00 pm
DEN
- STL
Nonstop2h 13m
Frontier
Deal found 7/27![Frontier logo]()
$135
This United Airlines deal was found by Cheapflights users on 7/28. 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 8/259:00 am
STL
- DEN
Nonstop2h 31m
United Airlines
Tue 9/11:27 pm
DEN
- STL
Nonstop2h 07m
United Airlines
Deal found 7/28![United Airlines logo]()
$157
This Kiwi.com deal was found by Cheapflights users on 7/27. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/277:58 pm
STL
- DEN
Nonstop2h 27m
Frontier
Sat 8/2911:59 pm
DEN
- STL
1 stop16h 23m
Frontier
Deal found 7/27![Frontier logo]()
$140
This Kiwi.com deal was found by Cheapflights users on 7/27. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/286:17 pm
STL
- DEN
1 stop16h 02m
Frontier
Mon 8/314:00 pm
DEN
- STL
Nonstop2h 13m
Frontier
Deal found 7/27![Frontier logo]()
$141
This Kiwi.com deal was found by Cheapflights users on 7/28. 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.
Sat 8/292:41 pm
ORD
- DEN
Nonstop3h 04m
Frontier
Mon 8/319:06 pm
DEN
- ORD
1 stop17h 53m
Frontier
Deal found 7/28![Frontier logo]()
$158
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 July 29, 2026.
Search for one-way flight options from Illinois to Colorado. Find affordable one-way fares based on user searches. Data last updated July 29, 2026.
This Kiwi.com deal was found by Cheapflights users on 7/25. 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 8/246:17 pm
STL
- DEN
1 stop28h 48m
Frontier
Deal found 7/25![Frontier logo]()
$91
This Kiwi.com deal was found by Cheapflights users on 7/25. 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 10/72:29 pm
STL
- DEN
1 stop7h 34m
Frontier
Deal found 7/25![Frontier logo]()
$92
This United Airlines deal was found by Cheapflights users on 7/27. 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.
Sat 8/229:00 am
STL
- DEN
Nonstop2h 31m
United Airlines
Deal found 7/27![United Airlines logo]()
$94
This Kiwi.com deal was found by Cheapflights users on 7/23. 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 9/610:07 am
PIA
- DEN
Nonstop2h 20m
Allegiant Air
Deal found 7/23![Allegiant Air logo]()
$95
This Kiwi.com deal was found by Cheapflights users on 7/28. 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.
Mon 9/212:29 pm
STL
- DEN
2 stops22h 41m
Frontier
Deal found 7/28![Frontier logo]()
$95
This Kiwi.com deal was found by Cheapflights users on 7/27. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/162:29 pm
STL
- DEN
1 stop7h 34m
Frontier
Deal found 7/27![Frontier logo]()
$96
This Kiwi.com deal was found by Cheapflights users on 7/26. 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 10/2310:35 am
STL
- DEN
1 stop23h 56m
Frontier
Deal found 7/26![Frontier logo]()
$97
This Southwest deal was found by Cheapflights users on 7/28. 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.
Thu 8/208:30 am
STL
- DEN
1 stop3h 30m
Southwest
Deal found 7/28![Southwest logo]()
$99
This Cheapflightsfares deal was found by Cheapflights users on 7/24. 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.
Thu 10/85:24 pm
PIA
- DEN
Nonstop2h 20m
Allegiant Air
Deal found 7/24![Allegiant Air logo]()
$101
This Cheapflightsfares deal was found by Cheapflights users on 7/28. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/287:58 pm
STL
- DEN
Nonstop2h 27m
Frontier
Deal found 7/28![Frontier logo]()
$101
This Cheapflightsfares deal was found by Cheapflights users on 7/27. 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.
Sat 8/19:57 pm
ORD
- DEN
Nonstop3h 00m
Frontier
Deal found 7/27![Frontier logo]()
$102
This Southwest deal was found by Cheapflights users on 7/23. 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 9/125:05 pm
MDW
- DEN
Nonstop2h 45m
Southwest
Deal found 7/23![Southwest logo]()
$103
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 July 29, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $135 (Kiwi.com) |
One-way from | $91 (Kiwi.com) |
Popular in | July |
Cheapest in | October |
Average price | $308 |
Good round-trip deal | $230 or less |
Good one-way deal | $148 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 July 29, 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
Quickest round-trip
St. LouisDenver
STL - DEN
STLDEN
Lambert-St Louis
Tue 8/18
12:20 pm-1:35 pm
Nonstop2h 15m
Denver Intl
Sat 8/22
7:35 am-10:35 am
Nonstop2h 00m
$172
St. LouisDenver
STL - DEN
STLDEN
Lambert-St Louis
Mon 8/17
8:45 pm-10:00 pm
Nonstop2h 15m
Denver Intl
Sat 8/22
7:35 am-10:35 am
Nonstop2h 00m
$187
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Sat 8/22
5:05 pm-6:45 pm
Nonstop2h 40m
Denver Intl
Sat 8/29
7:15 am-10:35 am
Nonstop2h 20m
$205
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Sat 8/29
6:50 am-8:20 am
Nonstop2h 30m
Denver Intl
Mon 8/31
6:30 pm-10:00 pm
Nonstop2h 30m
$205
St. LouisDenver
STL - DEN
STLDEN
Lambert-St Louis
Thu 8/27
3:45 pm-8:00 pm
1 stop5h 15m
Denver Intl
Mon 8/31
11:10 am-6:05 pm
1 stop5h 55m
$207
ChicagoDenver
ORD - DEN
ORDDEN
Chicago O'Hare Intl
Sat 8/15
6:00 am-7:39 am
Nonstop2h 39m
Denver Intl
Thu 8/20
5:47 pm-9:29 pm
Nonstop2h 42m
$213
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Sat 8/15
6:00 pm-7:40 pm
Nonstop2h 40m
Denver Intl
Wed 8/19
7:25 pm-10:50 pm
Nonstop2h 25m
$213
ChicagoDenver
ORD - DEN
ORDDEN
Chicago O'Hare Intl
Thu 9/3
5:00 am-6:39 am
Nonstop2h 39m
Denver Intl
Sun 9/6
6:18 pm-10:00 pm
Nonstop2h 42m
$214
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Wed 8/19
1:55 pm-7:50 pm
2 stops6h 55m
Denver Intl
Thu 8/27
3:15 pm-7:45 pm
1 stop3h 30m
$221
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Tue 10/27
1:05 pm-4:55 pm
1 stop4h 50m
Denver Intl
Tue 11/3
2:20 pm-7:35 pm
1 stop4h 15m
$224
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
PIA-DEN
ORD-DEN
ORD-COS
ORD-GJT
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
PIA-DEN
ORD-DEN
ORD-COS
What is the cheapest month to book a flight from Illinois to Colorado?
Currently, October is the cheapest month in which you can book a flight from Illinois to Colorado (average of $231). Flying from Illinois to Colorado in June is currently the most expensive (average of $343). 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 July 29, 2026.
It’s optimal to fly from Illinois to Colorado at noon. By choosing this option you can save up to 14% on the cost of your flight, compared to a flight in the evening.
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 July 29, 2026.
The most flights from USIL to USCO are scheduled on a Tuesday (66 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (25 on average).
How much does it cost to fly round-trip from Illinois to Colorado?
Airfare is below average for this route at the moment.
Illinois to Colorado flights typically cost between $181 and $323 in August.The cheapest round-trip price found within the last 5 days was $157 on Frontier (Aug 21-Aug 24).
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 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 July 20, 2025.
Travelers seeking maximum savings on their Illinois to Colorado flight should consider departing on Wednesday afternoons when fares are most often at their lowest. Sunday at noon flights should be avoided if possible as fares are typically the most expensive at this time.
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 July 29, 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.
Comfort
8.0
Food
7.0
Entertainment
7.5
Crew
8.6
Boarding
8.1
Overall
8.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Comfort
8.0
Food
7.0
Entertainment
7.5
Crew
8.6
Boarding
8.1
Overall
8.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Comfort
8.0
Food
7.0
Entertainment
7.5
Crew
8.6
Boarding
8.1
Overall
8.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Comfort
8.0
Food
7.0
Entertainment
7.5
Crew
8.6
Boarding
8.1
Overall
8.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Comfort
8.0
Food
7.0
Entertainment
7.5
Crew
8.6
Boarding
8.1
Overall
8.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Comfort
8.0
Food
7.0
Entertainment
7.5
Crew
8.6
Boarding
8.1
Overall
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 July 29, 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 7 airlines flying from Illinois to Colorado
Discover the top 7 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 July 29, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$68 | Average$176 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$74 | Average$265 | FlexibilityNo cancel fee | On-time88% | |
| Cheapest$105 | Average$341 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$145 | Average$223 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$151 | Average$352 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$156 | Average$403 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$168 | Average$401 | FlexibilityNo cancel fee | On-time69% |