$81+ 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 8/5. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — DEN
Jul 16 — Jul 231
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 June 16, 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 June 16, 2026.
This deal was found by Cheapflights users on 6/12. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/88:10 pm
STL
- DEN
Nonstop2h 39m
Frontier
Mon 10/124:12 pm
DEN
- STL
Nonstop2h 03m
Frontier
Deal found 6/12![Frontier logo]()
$142
This Kiwi.com deal was found by Cheapflights users on 6/11. 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.
Mon 8/178:08 pm
STL
- DEN
Nonstop2h 36m
Frontier
Tue 8/189:25 pm
DEN
- STL
1 stop16h 23m
Frontier
Deal found 6/11![Frontier logo]()
$145
This Kiwi.com deal was found by Cheapflights users on 6/11. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/268:08 pm
STL
- DEN
Nonstop2h 36m
Frontier
Wed 9/24:12 pm
DEN
- STL
Nonstop2h 11m
Frontier
Deal found 6/11![Frontier logo]()
$151
This Frontier deal was found by Cheapflights users on 6/11. 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.
Tue 7/218:08 pm
STL
- DEN
Nonstop2h 36m
Frontier
Sat 7/254:10 pm
DEN
- STL
Nonstop2h 13m
Frontier
Deal found 6/11![Frontier logo]()
$153
This Cheapflightsfares deal was found by Cheapflights users on 6/11. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/108:08 pm
STL
- DEN
Nonstop2h 36m
Frontier
Thu 8/134:10 pm
DEN
- STL
Nonstop2h 13m
Frontier
Deal found 6/11![Frontier logo]()
$154
This Cheapflightsfares deal was found by Cheapflights users on 6/14. 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.
Sun 8/95:23 pm
PIA
- DEN
Nonstop2h 25m
Allegiant Air
Thu 8/134:27 pm
DEN
- PIA
Nonstop2h 10m
Allegiant Air
Deal found 6/14![Allegiant Air logo]()
$155
This Frontier deal was found by Cheapflights users on 6/14. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/288:08 pm
STL
- DEN
Nonstop2h 36m
Frontier
Mon 8/314:12 pm
DEN
- STL
Nonstop2h 11m
Frontier
Deal found 6/14![Frontier logo]()
$158
This Cheapflightsfares deal was found by Cheapflights users on 6/15. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/148:08 pm
STL
- DEN
Nonstop2h 36m
Frontier
Fri 8/284:12 pm
DEN
- STL
Nonstop2h 11m
Frontier
Deal found 6/15![Frontier logo]()
$160
This Cheapflightsfares deal was found by Cheapflights users on 6/12. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/128:08 pm
STL
- DEN
Nonstop2h 36m
Frontier
Thu 8/134:10 pm
DEN
- STL
Nonstop2h 13m
Frontier
Deal found 6/12![Frontier logo]()
$161
This Cheapflightsfares deal was found by Cheapflights users on 6/14. 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 8/108:08 pm
STL
- DEN
Nonstop2h 36m
Frontier
Wed 8/124:10 pm
DEN
- STL
Nonstop2h 13m
Frontier
Deal found 6/14![Frontier logo]()
$162
This Cheapflightsfares deal was found by Cheapflights users on 6/15. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/148:08 pm
STL
- DEN
Nonstop2h 36m
Frontier
Sat 7/184:10 pm
DEN
- STL
Nonstop2h 13m
Frontier
Deal found 6/15![Frontier logo]()
$163
This Frontier deal was found by Cheapflights users on 6/12. 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.
Tue 7/218:08 pm
STL
- DEN
Nonstop2h 36m
Frontier
Tue 7/284:10 pm
DEN
- STL
Nonstop2h 13m
Frontier
Deal found 6/12![Frontier logo]()
$164
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 June 16, 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 June 16, 2026.
This Southwest deal was found by Cheapflights users on 6/11. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/52:15 pm
MDW
- DEN
1 stop5h 15m
Southwest
Tue 9/811:15 am
DEN
- MDW
1 stop4h 45m
Southwest
Deal found 6/11![Southwest logo]()
$194
This Delta deal was found by Cheapflights users on 6/11. 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 9/53:00 pm
ORD
- DEN
1 stop5h 51m
Delta
Mon 9/712:55 am
DEN
- ORD
1 stop6h 01m
Delta
Deal found 6/11![Delta logo]()
$204
This United Airlines deal was found by Cheapflights users on 6/15. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/89:50 pm
ORD
- DEN
Nonstop2h 58m
United Airlines
Wed 7/159:05 pm
DEN
- ORD
Nonstop2h 39m
United Airlines
Deal found 6/15![United Airlines logo]()
$205
This American Airlines deal was found by Cheapflights users on 6/11. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/85:00 am
ORD
- GJT
1 stop7h 31m
American Airlines
Wed 7/154:55 pm
GJT
- ORD
1 stop6h 55m
American Airlines
Deal found 6/11![American Airlines logo]()
$299
This Southwest deal was found by Cheapflights users on 6/15. 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.
Wed 8/58:50 pm
MDW
- DEN
Nonstop2h 35m
Southwest
Mon 8/108:25 pm
DEN
- MDW
Nonstop2h 20m
Southwest
Deal found 6/15![Southwest logo]()
$216
This Delta deal was found by Cheapflights users on 6/11. 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.
Tue 7/286:30 am
ORD
- DEN
1 stop4h 33m
Delta
Tue 8/46:05 am
DEN
- ORD
1 stop6h 03m
Delta
Deal found 6/11![Delta logo]()
$217
This Kiwi.com deal was found by Cheapflights users on 6/11. 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 7/219:57 pm
ORD
- GJT
2 stops39h 16m
Multiple Airlines
Tue 7/2812:53 pm
GJT
- ORD
1 stop15h 44m
Multiple Airlines
Deal found 6/11![Multiple Airlines logo]()
$448
This United Airlines deal was found by Cheapflights users on 6/15. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/295:10 am
STL
- DEN
Nonstop2h 22m
United Airlines
Tue 8/46:00 am
DEN
- STL
1 stop5h 11m
United Airlines
Deal found 6/15![United Airlines logo]()
$237
This Southwest deal was found by Cheapflights users on 6/12. 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.
Tue 7/215:30 am
MDW
- DEN
Nonstop2h 35m
Southwest
Tue 7/287:40 am
DEN
- MDW
1 stop3h 45m
Southwest
Deal found 6/12![Southwest logo]()
$223
This Delta deal was found by Cheapflights users on 6/11. 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.
Fri 8/2811:22 am
ORD
- DEN
1 stop7h 01m
Delta
Mon 8/3110:19 am
DEN
- ORD
1 stop4h 58m
Delta
Deal found 6/11![Delta logo]()
$227
This Southwest deal was found by Cheapflights users on 6/11. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/612:05 pm
MDW
- DEN
1 stop4h 55m
Southwest
Mon 8/105:00 am
DEN
- MDW
1 stop5h 00m
Southwest
Deal found 6/11![Southwest logo]()
$226
This Delta deal was found by Cheapflights users on 6/12. 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 8/265:20 pm
ORD
- DEN
1 stop6h 28m
Delta
Sat 8/296:00 am
DEN
- ORD
1 stop4h 37m
Delta
Deal found 6/12![Delta logo]()
$236
This United Airlines deal was found by Cheapflights users on 6/11. 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.
Sun 11/159:30 pm
ORD
- DEN
Nonstop2h 33m
United Airlines
Sun 11/224:45 pm
DEN
- ORD
Nonstop2h 45m
United Airlines
Deal found 6/11![United Airlines logo]()
$265
This Southwest deal was found by Cheapflights users on 6/13. 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.
Wed 8/268:55 am
MDW
- DEN
1 stop5h 00m
Southwest
Mon 8/318:25 pm
DEN
- MDW
Nonstop2h 20m
Southwest
Deal found 6/13![Southwest logo]()
$233
This American Airlines deal was found by Cheapflights users on 6/13. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/215:00 am
ORD
- GJT
1 stop7h 37m
American Airlines
Mon 8/244:42 pm
GJT
- ORD
1 stop6h 36m
American Airlines
Deal found 6/13![American Airlines logo]()
$314
This United Airlines deal was found by Cheapflights users on 6/13. 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.
Mon 7/65:00 am
ORD
- DEN
Nonstop2h 42m
United Airlines
Tue 7/77:10 pm
DEN
- ORD
Nonstop2h 39m
United Airlines
Deal found 6/13![United Airlines logo]()
$265
This Delta deal was found by Cheapflights users on 6/15. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/86:24 pm
ORD
- DEN
1 stop6h 11m
Delta
Mon 9/1411:00 am
DEN
- ORD
1 stop8h 22m
Delta
Deal found 6/15![Delta logo]()
$246
This Southwest deal was found by Cheapflights users on 6/13. 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.
Thu 8/278:45 pm
MDW
- DEN
Nonstop2h 35m
Southwest
Tue 9/14:30 pm
DEN
- MDW
Nonstop2h 20m
Southwest
Deal found 6/13![Southwest logo]()
$235
This Delta deal was found by Cheapflights users on 6/11. 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.
Thu 10/225:20 pm
ORD
- DEN
1 stop6h 39m
Delta
Sun 10/256:45 am
DEN
- ORD
1 stop4h 52m
Delta
Deal found 6/11![Delta logo]()
$248
This Southwest deal was found by Cheapflights users on 6/14. 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.
Mon 8/318:45 pm
MDW
- DEN
Nonstop2h 35m
Southwest
Sun 9/67:50 am
DEN
- MDW
Nonstop2h 25m
Southwest
Deal found 6/14![Southwest logo]()
$246
This United Airlines deal was found by Cheapflights users on 6/14. 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 8/222:42 pm
ORD
- COS
1 stop6h 12m
United Airlines
Sat 8/2911:55 am
COS
- ORD
Nonstop2h 43m
United Airlines
Deal found 6/14![United Airlines logo]()
$305
This Delta deal was found by Cheapflights users on 6/14. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/225:54 pm
ORD
- DEN
1 stop6h 33m
Delta
Sun 7/2612:59 am
DEN
- ORD
1 stop6h 00m
Delta
Deal found 6/14![Delta logo]()
$255
This Southwest deal was found by Cheapflights users on 6/13. 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 8/285:00 pm
MDW
- DEN
1 stop3h 50m
Southwest
Mon 8/318:25 am
DEN
- MDW
Nonstop2h 25m
Southwest
Deal found 6/13![Southwest logo]()
$252
This United Airlines deal was found by Cheapflights users on 6/15. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/288:46 am
ORD
- COS
Nonstop2h 47m
United Airlines
Tue 9/111:55 am
COS
- ORD
Nonstop2h 43m
United Airlines
Deal found 6/15![United Airlines logo]()
$311
This Delta deal was found by Cheapflights users on 6/13. 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.
Mon 7/205:54 pm
ORD
- DEN
1 stop6h 33m
Delta
Sun 8/2312:59 am
DEN
- ORD
1 stop5h 57m
Delta
Deal found 6/13![Delta logo]()
$266
This Southwest deal was found by Cheapflights users on 6/11. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 7/115:25 am
MDW
- DEN
Nonstop2h 35m
Southwest
Tue 7/217:00 pm
DEN
- MDW
Nonstop2h 30m
Southwest
Deal found 6/11![Southwest logo]()
$255
This Delta deal was found by Cheapflights users on 6/15. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/135:20 pm
ORD
- DEN
1 stop6h 28m
Delta
Fri 8/146:05 am
DEN
- ORD
1 stop6h 03m
Delta
Deal found 6/15![Delta logo]()
$266
This United Airlines deal was found by Cheapflights users on 6/11. 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.
Wed 7/89:06 am
ORD
- COS
Nonstop3h 03m
United Airlines
Thu 7/95:44 am
COS
- ORD
Nonstop3h 01m
United Airlines
Deal found 6/11![United Airlines logo]()
$329
This Southwest deal was found by Cheapflights users on 6/15. 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.
Sun 8/237:55 am
MDW
- DEN
Nonstop2h 45m
Southwest
Wed 8/264:30 pm
DEN
- MDW
Nonstop2h 20m
Southwest
Deal found 6/15![Southwest logo]()
$255
This United Airlines deal was found by Cheapflights users on 6/11. 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.
Wed 8/124:40 pm
STL
- DEN
Nonstop2h 30m
United Airlines
Mon 8/175:35 pm
DEN
- STL
Nonstop2h 11m
United Airlines
Deal found 6/11![United Airlines logo]()
$332
Last-minute flights from Illinois to ColoradoDiscover last-minute flight deals from Illinois to Colorado. Data last updated June 16, 2026 and is based on user searches.
Discover last-minute flight deals from Illinois to Colorado. Data last updated June 16, 2026 and is based on user searches.
This Frontier deal was found by Cheapflights users on 6/13. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/239:48 pm
ORD
- DEN
Nonstop3h 06m
Frontier
Sat 7/45:05 pm
DEN
- ORD
Nonstop2h 38m
Frontier
Deal found 6/13![Frontier logo]()
$220
This Cheapflightsfares deal was found by Cheapflights users on 6/11. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 6/249:48 pm
ORD
- DEN
Nonstop3h 06m
Frontier
Sat 7/45:05 pm
DEN
- ORD
Nonstop2h 38m
Frontier
Deal found 6/11![Frontier logo]()
$201
This Cheapflightsfares deal was found by Cheapflights users on 6/16. 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 6/249:48 pm
ORD
- DEN
Nonstop3h 06m
Frontier
Fri 7/35:05 pm
DEN
- ORD
Nonstop2h 38m
Frontier
Deal found 6/16![Frontier logo]()
$221
This Cheapflightsfares deal was found by Cheapflights users on 6/11. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 6/262:56 pm
STL
- DEN
1 stop19h 34m
Frontier
Wed 7/14:12 pm
DEN
- STL
Nonstop2h 11m
Frontier
Deal found 6/11![Frontier logo]()
$219
This Southwest deal was found by Cheapflights users on 6/15. 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.
Tue 7/75:30 am
MDW
- DEN
Nonstop2h 35m
Southwest
Tue 7/1412:20 pm
DEN
- MDW
1 stop3h 45m
Southwest
Deal found 6/15![Southwest logo]()
$211
This Southwest deal was found by Cheapflights users on 6/15. 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.
Tue 7/75:30 am
MDW
- DEN
Nonstop2h 35m
Southwest
Wed 7/812:05 pm
DEN
- MDW
1 stop5h 10m
Southwest
Deal found 6/15![Southwest logo]()
$215
This Cheapflightsfares deal was found by Cheapflights users on 6/11. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 7/1911:07 am
PIA
- DEN
Nonstop2h 23m
Allegiant Air
Thu 7/304:24 pm
DEN
- PIA
Nonstop2h 10m
Allegiant Air
Deal found 6/11![Allegiant Air logo]()
$210
This Southwest deal was found by Cheapflights users on 6/12. 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.
Tue 7/216:00 pm
MDW
- DEN
Nonstop2h 45m
Southwest
Tue 7/286:15 am
DEN
- MDW
Nonstop2h 25m
Southwest
Deal found 6/12![Southwest logo]()
$217
This Southwest deal was found by Cheapflights users on 6/11. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/289:05 pm
MDW
- DEN
Nonstop2h 50m
Southwest
Tue 8/411:15 am
DEN
- MDW
1 stop4h 45m
Southwest
Deal found 6/11![Southwest logo]()
$194
This Expedia deal was found by Cheapflights users on 6/12. 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/2812:11 pm
MDW
- DEN
1 stop10h 54m
Frontier
Tue 8/410:09 am
DEN
- MDW
1 stop5h 42m
Frontier
Deal found 6/12![Frontier logo]()
$220
This Southwest deal was found by Cheapflights users on 6/12. 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.
Wed 7/297:00 am
MDW
- DEN
Nonstop2h 35m
Southwest
Tue 8/411:15 am
DEN
- MDW
1 stop4h 45m
Southwest
Deal found 6/12![Southwest logo]()
$188
This Southwest deal was found by Cheapflights users on 6/14. 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.
Wed 7/295:30 am
MDW
- DEN
Nonstop2h 35m
Southwest
Wed 8/56:30 am
DEN
- MDW
Nonstop2h 20m
Southwest
Deal found 6/14![Southwest logo]()
$205
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 June 16, 2026.
Search for one-way flight options from Illinois to Colorado. Find affordable one-way fares based on user searches. Data last updated June 16, 2026.
This Frontier deal was found by Cheapflights users on 6/11. 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 8/58:08 pm
STL
- DEN
Nonstop2h 36m
Frontier
Deal found 6/11![Frontier logo]()
$81
This Kiwi.com deal was found by Cheapflights users on 6/11. 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 8/113:41 pm
STL
- DEN
1 stop8h 14m
Frontier
Deal found 6/11![Frontier logo]()
$83
This Cheapflightsfares deal was found by Cheapflights users on 6/14. 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.
Sun 8/95:23 pm
PIA
- DEN
Nonstop2h 25m
Allegiant Air
Deal found 6/14![Allegiant Air logo]()
$87
This Frontier deal was found by Cheapflights users on 6/11. 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.
Mon 7/68:08 pm
STL
- DEN
Nonstop2h 36m
Frontier
Deal found 6/11![Frontier logo]()
$89
This Frontier deal was found by Cheapflights users on 6/11. 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 7/118:08 pm
STL
- DEN
Nonstop2h 36m
Frontier
Deal found 6/11![Frontier logo]()
$90
This Kiwi.com deal was found by Cheapflights users on 6/13. 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.
Tue 9/83:33 pm
STL
- DEN
1 stop9h 20m
Frontier
Deal found 6/13![Frontier logo]()
$92
This Frontier deal was found by Cheapflights users on 6/11. 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.
Mon 10/268:10 pm
STL
- DEN
Nonstop2h 39m
Frontier
Deal found 6/11![Frontier logo]()
$97
This Kiwi.com deal was found by Cheapflights users on 6/13. 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.
Sat 7/119:57 pm
ORD
- DEN
Nonstop3h 00m
Frontier
Deal found 6/13![Frontier logo]()
$100
This Kiwi.com deal was found by Cheapflights users on 6/12. 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 9/232:46 pm
ORD
- DEN
1 stop10h 07m
Frontier
Deal found 6/12![Frontier logo]()
$101
This Southwest deal was found by Cheapflights users on 6/12. 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.
Tue 8/118:50 pm
MDW
- DEN
Nonstop2h 35m
Southwest
Deal found 6/12![Southwest logo]()
$103
This American Airlines deal was found by Cheapflights users on 6/16. 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.
Tue 7/1410:35 pm
ORD
- DEN
Nonstop2h 42m
American Airlines
Deal found 6/16![American Airlines logo]()
$103
This United Airlines deal was found by Cheapflights users on 6/15. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/81:38 pm
STL
- DEN
Nonstop2h 22m
United Airlines
Deal found 6/15![United Airlines 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 June 16, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $142 |
One-way from | $81 (Frontier) |
Popular in | March |
Cheapest in | October |
Average price | $278 |
Good round-trip deal | $247 or less |
Good one-way deal | $145 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 June 16, 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
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Sat 9/5
2:15 pm-6:30 pm
1 stop5h 15m
Denver Intl
Tue 9/8
11:15 am-5:00 pm
1 stop4h 45m
$194
ChicagoDenver
ORD - DEN
ORDDEN
Chicago O'Hare Intl
Sat 9/5
3:00 pm-7:51 pm
1 stop5h 51m
Denver Intl
Mon 9/7
12:55 am-7:56 am
1 stop6h 01m
$204
ChicagoDenver
ORD - DEN
ORDDEN
Chicago O'Hare Intl
Wed 7/8
9:50 pm-11:48 pm
Nonstop2h 58m
Denver Intl
Wed 7/15
9:05 pm-12:44 am
Nonstop2h 39m
$205
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Wed 8/5
8:50 pm-10:25 pm
Nonstop2h 35m
Denver Intl
Mon 8/10
8:25 pm-11:45 pm
Nonstop2h 20m
$216
ChicagoDenver
ORD - DEN
ORDDEN
Chicago O'Hare Intl
Tue 7/28
6:30 am-10:03 am
1 stop4h 33m
Denver Intl
Tue 8/4
6:05 am-1:08 pm
1 stop6h 03m
$217
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Tue 7/21
5:30 am-7:05 am
Nonstop2h 35m
Denver Intl
Tue 7/28
7:40 am-12:25 pm
1 stop3h 45m
$223
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Thu 8/6
12:05 pm-4:00 pm
1 stop4h 55m
Denver Intl
Mon 8/10
5:00 am-11:00 am
1 stop5h 00m
$226
ChicagoDenver
ORD - DEN
ORDDEN
Chicago O'Hare Intl
Fri 8/28
11:22 am-5:23 pm
1 stop7h 01m
Denver Intl
Mon 8/31
10:19 am-4:17 pm
1 stop4h 58m
$227
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Wed 8/26
8:55 am-12:55 pm
1 stop5h 00m
Denver Intl
Mon 8/31
8:25 pm-11:45 pm
Nonstop2h 20m
$233
ChicagoDenver
MDW - DEN
MDWDEN
Chicago Midway
Thu 8/27
8:45 pm-10:20 pm
Nonstop2h 35m
Denver Intl
Tue 9/1
4:30 pm-7:50 pm
Nonstop2h 20m
$235
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
MDW-DEN
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
MDW-DEN
What is the cheapest month to book a flight from Illinois to Colorado?
Currently, April is the cheapest month in which you can book a flight from Illinois to Colorado (average of $236). Flying from Illinois to Colorado in May is currently the most expensive (average of $333). 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 June 16, 2026.
It’s optimal to fly from Illinois to Colorado at noon. By choosing this option you can save up to 12% 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 June 16, 2026.
The most flights from USIL to USCO are scheduled on a Monday (64 on average). You will have fewer flight options on Wednesday, which is when the least amount of flights are scheduled (48 on average).
How much does it cost to fly round-trip from Illinois to Colorado?
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 Saturday afternoons when fares are most often at their lowest. Sunday mornings flights should be avoided if possible as fares are typically the most expensive at this time.
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 June 16, 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.
Food
7.0
Boarding
8.1
Crew
8.6
Comfort
8.0
Entertainment
7.5
Overall
7.9
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Food
7.0
Boarding
8.1
Crew
8.6
Comfort
8.0
Entertainment
7.5
Overall
7.9
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Food
7.0
Boarding
8.1
Crew
8.6
Comfort
8.0
Entertainment
7.5
Overall
7.9
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Food
7.0
Boarding
8.1
Crew
8.6
Comfort
8.0
Entertainment
7.5
Overall
7.9
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Food
7.0
Boarding
8.1
Crew
8.6
Comfort
8.0
Entertainment
7.5
Overall
7.9
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Food
7.0
Boarding
8.1
Crew
8.6
Comfort
8.0
Entertainment
7.5
Overall
7.9
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 June 16, 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 June 16, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$51 | Average$239 | FlexibilityNo cancel fee | On-time88% | |
| Cheapest$70 | Average$171 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$105 | Average$284 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$145 | Average$223 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$151 | Average$338 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$153 | Average$399 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$166 | Average$399 | FlexibilityNo cancel fee | On-time69% |