Flights from Chicago to Boulder

Cheapest flights from Chicago

These prices were available within the past 7 days. Prices quoted are per person, round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Wed, Jun 25 - Tue, Jul 1

ORD

O'Hare Intl.

DEN

Denver Intl.

$159 Roundtrip, found 1 day ago

$159

Roundtrip

found 1 day ago

Select Frontier Airlines flight, departing Wed, Jun 25 from O'Hare Intl. to Denver Intl., returning Tue, Jul 1, priced at $159 found 1 day ago

Wed, Jun 25 - Mon, Jun 30

ORD

O'Hare Intl.

DEN

Denver Intl.

$165 Roundtrip, found 1 day ago

$165

Roundtrip

found 1 day ago

Select Frontier Airlines flight, departing Wed, Jun 25 from O'Hare Intl. to Denver Intl., returning Mon, Jun 30, priced at $165 found 1 day ago

Sat, Jun 28 - Tue, Jul 1

ORD

O'Hare Intl.

DEN

Denver Intl.

$166 Roundtrip, found 1 day ago

$166

Roundtrip

found 1 day ago

Select Frontier Airlines flight, departing Sat, Jun 28 from O'Hare Intl. to Denver Intl., returning Tue, Jul 1, priced at $166 found 1 day ago

Fri, Jun 20 - Mon, Jun 23

ORD

O'Hare Intl.

DEN

Denver Intl.

$168 Roundtrip, found 5 days ago

$168

Roundtrip

found 5 days ago

Select Frontier Airlines flight, departing Fri, Jun 20 from O'Hare Intl. to Denver Intl., returning Mon, Jun 23, priced at $168 found 5 days ago

Wed, Jun 25 - Wed, Jun 25

ORD

O'Hare Intl.

DEN

Denver Intl.

$170 Roundtrip, found 1 day ago

$170

Roundtrip

found 1 day ago

Select Frontier Airlines flight, departing Wed, Jun 25 from O'Hare Intl. to Denver Intl., returning Wed, Jun 25, priced at $170 found 1 day ago

Sat, Jun 28 - Mon, Jun 30

ORD

O'Hare Intl.

DEN

Denver Intl.

$171 Roundtrip, found 1 day ago

$171

Roundtrip

found 1 day ago

Select Frontier Airlines flight, departing Sat, Jun 28 from O'Hare Intl. to Denver Intl., returning Mon, Jun 30, priced at $171 found 1 day ago

Wed, Jun 25 - Thu, Jun 26

ORD

O'Hare Intl.

DEN

Denver Intl.

$176 Roundtrip, found 1 day ago

$176

Roundtrip

found 1 day ago

Select Frontier Airlines flight, departing Wed, Jun 25 from O'Hare Intl. to Denver Intl., returning Thu, Jun 26, priced at $176 found 1 day ago

Sat, Jun 21 - Tue, Jun 24

ORD

O'Hare Intl.

DEN

Denver Intl.

$178 Roundtrip, found 5 days ago

$178

Roundtrip

found 5 days ago

Select Frontier Airlines flight, departing Sat, Jun 21 from O'Hare Intl. to Denver Intl., returning Tue, Jun 24, priced at $178 found 5 days ago

Sat, Jun 28 - Sat, Jun 28

ORD

O'Hare Intl.

DEN

Denver Intl.

$182 Roundtrip, found 1 day ago

$182

Roundtrip

found 1 day ago

Select Frontier Airlines flight, departing Sat, Jun 28 from O'Hare Intl. to Denver Intl., returning Sat, Jun 28, priced at $182 found 1 day ago

Sun, Jun 29 - Wed, Jul 2

ORD

O'Hare Intl.

DEN

Denver Intl.

$184 Roundtrip, found 1 day ago

$184

Roundtrip

found 1 day ago

Select Frontier Airlines flight, departing Sun, Jun 29 from O'Hare Intl. to Denver Intl., returning Wed, Jul 2, priced at $184 found 1 day ago

Tue, Jul 1 - Tue, Jul 1

ORD

O'Hare Intl.

DEN

Denver Intl.

$184 Roundtrip, found 1 day ago

$184

Roundtrip

found 1 day ago

Select Frontier Airlines flight, departing Tue, Jul 1 from O'Hare Intl. to Denver Intl., returning Tue, Jul 1, priced at $184 found 1 day ago

Tue, Jul 1 - Wed, Jul 2

ORD

O'Hare Intl.

DEN

Denver Intl.

$189 Roundtrip, found 1 day ago

$189

Roundtrip

found 1 day ago

Select Frontier Airlines flight, departing Tue, Jul 1 from O'Hare Intl. to Denver Intl., returning Wed, Jul 2, priced at $189 found 1 day ago

Fri, Jun 27 - Mon, Jun 30

ORD

O'Hare Intl.

DEN

Denver Intl.

$189 Roundtrip, found 1 day ago

$189

Roundtrip

found 1 day ago

Select Frontier Airlines flight, departing Fri, Jun 27 from O'Hare Intl. to Denver Intl., returning Mon, Jun 30, priced at $189 found 1 day ago

Wed, Jun 25 - Sun, Jun 29

ORD

O'Hare Intl.

DEN

Denver Intl.

$194 Roundtrip, found 1 day ago

$194

Roundtrip

found 1 day ago

Select Frontier Airlines flight, departing Wed, Jun 25 from O'Hare Intl. to Denver Intl., returning Sun, Jun 29, priced at $194 found 1 day ago

Fri, Aug 15 - Fri, Aug 22

MDW

Midway Intl.

DEN

Denver Intl.

$200 Roundtrip, found 6 days ago

$200

Roundtrip

found 6 days ago

Select Frontier Airlines flight, departing Fri, Aug 15 from Midway Intl. to Denver Intl., returning Fri, Aug 22, priced at $200 found 6 days ago

Sat, Jun 28 - Sun, Jun 29

ORD

O'Hare Intl.

DEN

Denver Intl.

$201 Roundtrip, found 1 day ago

$201

Roundtrip

found 1 day ago

Select United flight, departing Sat, Jun 28 from O'Hare Intl. to Denver Intl., returning Sun, Jun 29, priced at $201 found 1 day ago

Sat, Jun 28 - Sun, Jun 29

ORD

O'Hare Intl.

DEN

Denver Intl.

$201 Roundtrip, found 1 day ago

$201

Roundtrip

found 1 day ago

Select American Airlines flight, departing Sat, Jun 28 from O'Hare Intl. to Denver Intl., returning Sun, Jun 29, priced at $201 found 1 day ago

Tue, Jul 1 - Sat, Jul 5

ORD

O'Hare Intl.

DEN

Denver Intl.

$217 Roundtrip, found 1 day ago

$217

Roundtrip

found 1 day ago

Select Delta flight, departing Tue, Jul 1 from O'Hare Intl. to Denver Intl., returning Sat, Jul 5, priced at $217 found 1 day ago

Sat, Jun 28 - Sun, Jun 29

ORD

O'Hare Intl.

DEN

Denver Intl.

$293 Roundtrip, found 1 day ago

$293

Roundtrip

found 1 day ago

Select Sun Country Airlines flight, departing Sat, Jun 28 from O'Hare Intl. to Denver Intl., returning Sun, Jun 29, priced at $293 found 1 day ago

Sat, Jun 28 - Sun, Jun 29

ORD

O'Hare Intl.

DEN

Denver Intl.

$335 Roundtrip, found 1 day ago

$335

Roundtrip

found 1 day ago

Select KEY LIME AIR DBA DENVER AIR CONNECTION flight, departing Sat, Jun 28 from O'Hare Intl. to Denver Intl., returning Sun, Jun 29, priced at $335 found 1 day ago