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$59+ Cheap flights from Sky Harbor Intl (PHX) to Boulder, CO

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 10/17. Fares are subject to change and may not be available on all flights or dates of travel.
PHX — DEN
Aug 19 — Aug 261
Tue 8/19
Tue 8/26
1 adult, Economy
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Cheapflights Tip: The best prices from Phoenix Sky Harbor Intl to Boulder are usually found in February or January, booked 62 days in advance, depart on a Thursday or Friday and return on a Saturday

Cheap flight deals from Sky Harbor Intl to Boulder

Keep the following information in mind while searching for Sky Harbor Intl to Boulder flight deals. Data was last updated August 14, 2025.

Round-trip from

$100
(Frontier)

One-way from

$59
(Cheapflightsfares)

Popular in

June

Cheapest in

February

Average price

$156
From Phoenix Sky Harbor Intl to Boulder
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One-way flight from Phoenix Sky Harbor Intl to Boulder
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Highest demand for flights based on searches. 16% potential increase in price ($31 potential increase over avg. RT price).
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Cheapest flight prices on average. 1% potential price decrease ($4 potential savings vs. average RT price).
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Average for round-trip flights in August 2025
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Find flight deals from Sky Harbor Intl to Boulder

Cheapest flights from Sky Harbor Intl to Boulder
Explore the most affordable flight options available from Sky Harbor Intl to Boulder. Find the lowest fares from popular airlines and budget airlines, with prices last updated on August 14, 2025.

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.
Mon 9/17:09 amPHX - DEN
Nonstop1h 57mFrontier
Tue 9/98:55 pmDEN - PHX
Nonstop1h 58mFrontier
Deal found 8/12$100
This Cheapflightsfares 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/27:14 amPHX - DEN
Nonstop1h 57mFrontier
Tue 9/910:40 amDEN - PHX
Nonstop2h 02mFrontier
Deal found 8/12$103
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.
Thu 9/46:32 amPHX - DEN
Nonstop1h 58mFrontier
Sat 9/610:40 amDEN - PHX
Nonstop2h 02mFrontier
Deal found 8/12$104
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.
Sun 8/319:19 pmPHX - DEN
Nonstop2h 04mFrontier
Sat 9/610:40 amDEN - PHX
Nonstop2h 02mFrontier
Deal found 8/12$105
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.
Thu 10/912:02 pmPHX - DEN
Nonstop2h 01mFrontier
Sun 10/126:55 amDEN - PHX
Nonstop2h 04mFrontier
Deal found 8/14$106
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.
Wed 9/1712:39 pmPHX - DEN
Nonstop1h 57mFrontier
Sat 9/2010:30 amDEN - PHX
Nonstop2h 02mFrontier
Deal found 8/14$107
This Cheapflightsfares 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/208:00 amPHX - DEN
Nonstop2h 00mFrontier
Mon 9/2210:59 pmDEN - PHX
Nonstop1h 58mFrontier
Deal found 8/12$108
This Frontier 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 11/41:16 pmPHX - DEN
Nonstop2h 03mFrontier
Sat 11/87:55 pmDEN - PHX
Nonstop2h 00mFrontier
Deal found 8/13$109
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.
Wed 10/157:30 pmPHX - DEN
Nonstop1h 56mFrontier
Sat 10/1810:10 amDEN - PHX
Nonstop2h 04mFrontier
Deal found 8/13$110
This Cheapflightsfares 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/238:00 amPHX - DEN
Nonstop2h 00mFrontier
Thu 10/96:55 amDEN - PHX
Nonstop2h 04mFrontier
Deal found 8/12$112
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.
Thu 9/118:20 pmPHX - DEN
Nonstop1h 56mFrontier
Thu 9/186:10 amDEN - PHX
1 stop6h 16mFrontier
Deal found 8/14$113
This Frontier 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/297:00 amPHX - DEN
Nonstop1h 59mFrontier
Tue 10/72:01 pmDEN - PHX
Nonstop2h 03mFrontier
Deal found 8/13$114

Cheapflights Fare Finder

 
Customize your flight search to find flights from Sky Harbor Intl to Boulder 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 14, 2025.
Use the filters below to find and compare flights from Phoenix Sky Harbor Intl Airport to Boulder that are best for you.

Fly from

Sky Harbor Intl

Fly to

Boulder

Route

Depart

Return

Price

PhoenixDenver

PHX - DEN

PHXDEN

Phoenix Sky Harbor Intl

Fri 9/26

6:18 pm-9:12 pm

Nonstop1h 54m

Denver Intl

Sat 10/4

10:30 am-11:32 am

Nonstop2h 02m

$100

PhoenixDenver

PHX - DEN

PHXDEN

Phoenix Sky Harbor Intl

Thu 9/4

6:18 pm-9:12 pm

Nonstop1h 54m

Denver Intl

Sat 9/13

10:40 am-11:42 am

Nonstop2h 02m

$103

PhoenixDenver

PHX - DEN

PHXDEN

Phoenix Sky Harbor Intl

Sat 9/27

8:00 am-11:00 am

Nonstop2h 00m

Denver Intl

Sat 10/4

8:55 pm-9:53 pm

Nonstop1h 58m

$103

PhoenixDenver

PHX - DEN

PHXDEN

Phoenix Sky Harbor Intl

Thu 9/18

8:20 pm-11:16 pm

Nonstop1h 56m

Denver Intl

Wed 9/24

8:55 pm-9:53 pm

Nonstop1h 58m

$103

PhoenixDenver

PHX - DEN

PHXDEN

Phoenix Sky Harbor Intl

Thu 9/4

6:32 am-9:30 am

Nonstop1h 58m

Denver Intl

Sat 9/6

10:40 am-11:42 am

Nonstop2h 02m

$104

PhoenixDenver

PHX - DEN

PHXDEN

Phoenix Sky Harbor Intl

Sat 10/11

4:14 pm-7:10 pm

Nonstop1h 56m

Denver Intl

Mon 10/13

7:23 pm-8:23 pm

Nonstop2h 00m

$104

PhoenixDenver

PHX - DEN

PHXDEN

Phoenix Sky Harbor Intl

Fri 10/24

9:59 pm-12:56 am

Nonstop1h 57m

Denver Intl

Tue 10/28

8:55 pm-9:55 pm

Nonstop2h 00m

$106

PhoenixDenver

PHX - DEN

PHXDEN

Phoenix Sky Harbor Intl

Thu 10/9

12:02 pm-3:03 pm

Nonstop2h 01m

Denver Intl

Sun 10/12

6:55 am-7:59 am

Nonstop2h 04m

$106

PhoenixDenver

PHX - DEN

PHXDEN

Phoenix Sky Harbor Intl

Sat 9/6

12:39 pm-3:36 pm

Nonstop1h 57m

Denver Intl

Tue 9/9

8:55 pm-9:53 pm

Nonstop1h 58m

$107

PhoenixDenver

PHX - DEN

PHXDEN

Phoenix Sky Harbor Intl

Sat 9/27

8:00 am-11:00 am

Nonstop2h 00m

Denver Intl

Thu 10/2

10:29 pm-11:27 pm

Nonstop1h 58m

$107

Flights are sorted by cheapest round-trip flights first.

Deals found on 8/13

Showing 1-10 of 20 results
1
2

Best time to book a flight from Sky Harbor Intl to Boulder

Have a flexible travel schedule? Discover the best time to fly to Boulder from Sky Harbor Intl with our price prediction graph.
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 Phoenix Sky Harbor Intl Airport to Boulder

How far ahead should I book a flight from Phoenix Sky Harbor Intl Airport to Boulder?

Use this chart to determine the optimal time to book a round-trip flight from Sky Harbor Intl to Boulder. Price data was last updated on August 8, 2025.

To ensure you get the cheapest price possible for a flight from Phoenix Sky Harbor Intl Airport to Boulder, you should look to book at least 62 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 month to book a flight from Phoenix Sky Harbor Intl Airport to Boulder?

Currently, October is the cheapest month in which you can book a flight from Phoenix Sky Harbor Intl Airport to Boulder (average of $197). Flying from Phoenix Sky Harbor Intl Airport to Boulder in March is currently the most expensive (average of $278). 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 PHX to BD9?

Find hourly flight availability from Sky Harbor Intl to Boulder. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated August 14, 2025.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Phoenix Sky Harbor Intl Airport to Boulder as you normally would.

What is the cheapest day to fly from Phoenix Sky Harbor Intl Airport to Boulder?

Use this chart to determine the cheapest time to fly round-trip from Sky Harbor Intl to Boulder. Price data was last updated on December 16, 2024.

Travelers seeking maximum savings on their Phoenix Sky Harbor Intl Airport to Boulder flight should consider departing on Wednesday evenings 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.

Weekly flight availability from Phoenix Sky Harbor Intl Airport to Boulder

Explore weekly flight availability from Sky Harbor Intl to Boulder. 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 14, 2025.

The most flights from PHX to BD9 are scheduled on a Thursday (33 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (11 on average).

Reviews of airlines servicing Boulder

Get insights into the airlines that provide service to Boulder. 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 Boulder. Reviews last updated August 14, 2025.
Read through reviews of airlines operating flights from Phoenix Sky Harbor Intl Airport to Boulder, such as Southwest, United Airlines, and American Airlines. Reviews also offer insight into each airline's entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.0
Very good
4,244 reviews

Overall

8.0

Entertainment

7.5

Comfort

8.0

Boarding

8.1

Crew

8.6

Food

7.0

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
Southwest
8.0
Very good
4,244 reviews
Southwest
8.0
Very good
4,244 reviews

Overall

8.0

Entertainment

7.5

Comfort

8.0

Boarding

8.1

Crew

8.6

Food

7.0

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
United Airlines
7.4
Good
8,916 reviews
Southwest
8.0
Very good
4,244 reviews

Overall

8.0

Entertainment

7.5

Comfort

8.0

Boarding

8.1

Crew

8.6

Food

7.0

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
American Airlines
7.2
Good
10,000 reviews
Southwest
8.0
Very good
4,244 reviews

Overall

8.0

Entertainment

7.5

Comfort

8.0

Boarding

8.1

Crew

8.6

Food

7.0

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
Frontier
5.8
Fair
3,217 reviews
Southwest
8.0
Very good
4,244 reviews

Overall

8.0

Entertainment

7.5

Comfort

8.0

Boarding

8.1

Crew

8.6

Food

7.0

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.

Related info for your journey

Find useful and relevant information for your journey from Sky Harbor Intl to Boulder. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What are the most reliable airlines from Phoenix Sky Harbor Intl Airport to Boulder?

    Consider Air Canada (72%), United Airlines (72%) or Lufthansa (70%) when booking your flight. These represent the most reliable airlines when flying from Phoenix Sky Harbor Intl Airport to Boulder.

  • What are the cheapest flights from Phoenix Sky Harbor Intl Airport to Boulder?

    Looking at all options, your cheapest flight can be booked for $72. While the most popular route (Phoenix Sky Harbor Intl - Denver Intl) can be booked for $117 on average our data indicates $804 when flying from Phoenix Sky Harbor Intl Airport to Boulder.

  • Can I find deals for flights from Sky Harbor Intl to Boulder that include hotel bookings?

    Yes. In addition to deals on Sky Harbor Intl to Boulder flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Sky Harbor Intl to Boulder?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Sky Harbor Intl to Boulder.

  • Can I find deals for business class flights from Sky Harbor Intl to Boulder?

    Yes. Cheapflights offers flight deals from Sky Harbor Intl to Boulder by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from Phoenix Sky Harbor Intl Airport to Boulder?

    Currently, October is the cheapest month in which you can book a flight from Phoenix Sky Harbor Intl Airport to Boulder (average of $197). Flying from Phoenix Sky Harbor Intl Airport to Boulder in March is currently the most expensive (average of $278). 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.

See more FAQs

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Top 5 airlines flying from Sky Harbor Intl to Boulder

Discover the top 5 airlines that operate flights from Sky Harbor Intl to Boulder. 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 14, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$57Average$136FlexibilityNo cancel feeOn-time62%
American AirlinesCheapest$137Average$221FlexibilityNo cancel feeOn-time71%
SouthwestCheapest$146Average$267FlexibilityNo cancel feeOn-time63%
United AirlinesCheapest$147Average$317FlexibilityNo cancel feeOn-time69%
DeltaCheapest$218Average$258FlexibilityNo cancel feeOn-timeN/A

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