$49 Find Cheap Flights from Phoenix to Boulder

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Phoenix to Boulder departing on 2/14. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy, 0 bags

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Everything you should know

Cheapest round-trip
$63
Overall average: $105
Frontier
Wed 2/11Wed 2/18
PHX - DEN • Non-stop
Cheapest one-way
$49
Typical prices: $61-$180
Frontier
Sat 2/14
PHX - DEN • Non-stop
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Flight Deals
Useful Info
Flight Deals

Cheap Flights from Phoenix to Boulder (PHX-DEN)

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Phoenix to Boulder that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from Phoenix to Boulder

Wed, Feb 11 - Wed, Feb 18
Frontier Logo
9:52 am - 11:50 am
PHX
-
DEN
1h 58mnonstop
Frontier Logo
3:09 pm - 5:19 pm
DEN
-
PHX
2h 10mnonstop
$63Frontier
Sat, Feb 21 - Mon, Feb 23
Frontier Logo
10:51 pm - 12:42 am
PHX
-
DEN
1h 51mnonstop
Frontier Logo
7:20 pm - 9:29 pm
DEN
-
PHX
2h 09mnonstop
$64Frontier
Fri, Feb 27 - Sun, Mar 1
Frontier Logo
1:41 pm - 3:35 pm
PHX
-
DEN
1h 54mnonstop
Frontier Logo
6:00 am - 8:12 am
DEN
-
PHX
2h 12mnonstop
$65Frontier
Thu, Feb 26 - Mon, Mar 2
Frontier Logo
7:36 pm - 9:30 pm
PHX
-
DEN
1h 54mnonstop
Frontier Logo
4:16 pm - 6:26 pm
DEN
-
PHX
2h 10mnonstop
$66Frontier
Fri, Feb 13 - Wed, Feb 18
Frontier Logo
8:52 am - 10:49 am
PHX
-
DEN
1h 57mnonstop
Frontier Logo
6:30 am - 8:42 am
DEN
-
PHX
2h 12mnonstop
$67Frontier
Tue, Feb 10 - Tue, Feb 17
Frontier Logo
6:00 am - 7:54 am
PHX
-
DEN
1h 54mnonstop
Frontier Logo
9:50 pm - 11:59 pm
DEN
-
PHX
2h 09mnonstop
$68Frontier
Wed, Feb 18 - Thu, Feb 19
Frontier Logo
6:51 pm - 8:46 pm
PHX
-
DEN
1h 55mnonstop
Frontier Logo
6:00 am - 8:12 am
DEN
-
PHX
2h 12mnonstop
$69Frontier
Sat, Apr 11 - Wed, Apr 15
Frontier Logo
12:50 pm - 3:45 pm
PHX
-
DEN
1h 55mnonstop
Frontier Logo
10:40 pm - 11:47 pm
DEN
-
PHX
2h 07mnonstop
$70Frontier
Sat, Feb 14 - Mon, Feb 16
Frontier Logo
7:06 pm - 9:00 pm
PHX
-
DEN
1h 54mnonstop
Frontier Logo
10:30 pm - 12:41 am
DEN
-
PHX
2h 11mnonstop
$71Frontier
Sat, Feb 14 - Sun, Feb 15
Frontier Logo
7:06 pm - 9:00 pm
PHX
-
DEN
1h 54mnonstop
Frontier Logo
10:30 pm - 12:41 am
DEN
-
PHX
2h 11mnonstop
$72Frontier
Useful Info

Good to know

Low seasonApril
Cheapest flight$49
Best time to beat the crowds but there is an average 4% increase in price.
Most popular time to fly with an average 10% increase in price.
Flight from Phoenix Sky Harbor Airport to Denver

When to book flights from Phoenix to Boulder

Are your dates flexible? Find out the best times to travel from Phoenix to Boulder based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price

FAQs for booking flights from Phoenix to Boulder

  • Which airports will I be using when flying from Phoenix Sky Harbor Intl Airport to Boulder?

    When flying out of Phoenix Sky Harbor Intl Airport you’ll be using Phoenix Sky Harbor Intl. Boulder does not have its own airport so you’ll be flying into nearby Denver Intl airport, which is 33.4 mi away.

  • How long does a flight from Phoenix Sky Harbor Intl Airport to Boulder take?

    Direct flights cover the 601 miles separating Phoenix Sky Harbor Intl Airport and Boulder in about 1h 45m.

  • How many flights are there between Phoenix Sky Harbor Intl Airport and Boulder?

    73 direct flights run between Phoenix Sky Harbor Intl Airport and Boulder on a daily basis. On average, there are about 512 departures each week.

  • What’s the cheapest day of the week to fly between Phoenix Sky Harbor Intl Airport and Boulder?

    Consider leaving on a Friday and avoid Saturdays if you are looking for the best rates. For your return to Phoenix Sky Harbor Intl Airport, you’ll find the best rates on Mondays and the most expensive ones on Thursdays.

  • How does KAYAK find such low prices on flights from Phoenix to Boulder?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from Phoenix to Boulder.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Phoenix to Boulder?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to Boulder from Phoenix is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Phoenix to Boulder?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly to Boulder with an airline and back to Phoenix with another airline.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Phoenix to Boulder?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying to Boulder from Phoenix up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

  • Which airlines provide the cheapest flights from Phoenix Sky Harbor Intl Airport to Boulder?

    In the last 72 hours, the cheapest one-way ticket between Phoenix Sky Harbor Intl Airport and Boulder found on KAYAK was with Frontier for $33. Frontier offered a round-trip connection from $60 and United Airlines from $132.

Top tips for finding cheap flights from Phoenix Sky Harbor Intl Airport to Boulder

  • There is no airport in Boulder. Instead, you’ll be flying into Denver Airport when flying between Phoenix Sky Harbor Intl Airport and Boulder.
  • The cheapest flight from Phoenix to Boulder was found 73 days before departure, on average.
  • Book at least 2 weeks before departure in order to get a below-average price.
  • High season is considered to be May, June and July. The cheapest month to fly is February.

Reviews of the top 4 airlines serving Phoenix to Boulder

 
Need help choosing which airline to fly with from Phoenix to Boulder? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
8.0
SouthwestOverall score based on 4267 reviews
8.1Boarding
7.0Food
8.0Comfort
7.5Entertainment
8.6Crew
Airline reviews

All good except once again bags took an hour at Midway Airport Happens all the time. Ridiculous

10.0 ExcellentAnonymous, Jan 2026
PHX - MDW
Read more Southwest reviews

All good except once again bags took an hour at Midway Airport Happens all the time. Ridiculous

Sacrament staff are always polite and helpful. Airport is easy to maneuver and boarding is straightforward.

mandatory demand customer to check their carry on because not enough people check bags.

Near 4 hour flight with only 1 service. Had to use call button to request water. Internet and power not working until into flight. Internet would stop working during flight.

The Southwest employees (all two of them) were very nice and cheerful despite the fact the line to self-check a bag (simply drop it off) was hundreds of people long. Thank God I arrived early to the airport because I stood in this line for at least an hour. Once on the flight that had been delayed by an hour, we had no Wi-Fi and thus no entertainment. Finally, I hope the investor strong arm tactics against Southwest pay off in a short-term windfall to your C-Suite because the rest of you are screwed. I have been a faithful Southwest customer for 15 years due to everything you just got rid of. I'm flying to Idaho and Washington in October, both places I used to simply book with Southwest without a second thought now with Frontier (Washington) and United (Idaho) because they offer everything the "new" Southwest does but cheaper and at better times, destinations, etc. This really makes me sad...

First time traveling on Southwest since bag fees were implemented. Usual good service. Just more expensive now.

Flights delayed by 4-6 hours. Boarding was a mess and unclear. Bags were not at arrival airport and had never even been put on the plane. No idea when I’ll get them. Don’t fly into Denver!

Southwest is typically delayed, and it gets wearisome. It is no longer a discount airline and you get way less than you pay for when it comes to comfort and Ce.

We sat on the plane on the tarmac for 4 hours.

After a 3 hour layover in Denver my flight was delayed over 5 hours! No explanation; no assistance; no offer to provide compensation; no one at Southwest was willing to offer any assistance. 8 hours in the Denver airport - ridiculous!

Check-in, boarding and the flight from Phoenix to Houston was quick and easy. The flight from Houston to Shreveport was delayed 5 hours. It was frustrating but I think United handled it the best they could.

The flight was delayed by two de-icings. The seatbelt did not work correctly. It did not stay tight.

Hotter than Hades in August. Why, why do crews think that in the winter when we are already dressed for cold weather we need a cabin that is 82 degrees. Even the vents were blowing hot air.

Flight was delayed. De-icing took a while. When we landed had to wait for another plane to vacate our gate. Just an overall bad experience.

Not good - outbound flight was delayed and missed my connection even though I got to the gate after running through the airport - the agent would not let me on because the door was closed (flight had not left). There was no notification from United - overall experience was very disappointing. Additionally, I was downgraded from first class to coach on the alternative flight

United have really come back. Airport and boarding process is clear and good, app and information also very good

After boarding the plane in Chicago, the passengers were told that there was a technical problem with the plane. Passengers remained on the plane as they tried to fix the problem. After what was probably an hour passengers were told that there was a need to change planes as the problem was not solved. Passengers disembarked and boarded another plane. After taxing to the runway and waiting for takeoff, passengers were told that owing to the thunderstorm the flight was unable to take off but would try and reroute. After some time passengers were told there wasn't enough fuel for the new route and the plane had to return to the gate for additional fuel. after another log delay the flight got underway. On the plane there was food, drinks, ice or entertainment. We were a glass of water, which appeared rationed. Flight arrived about 5 hours late. The pilot was fantastic and communicated with the passengers throughout the ordeal.

The entertainment available didn’t work for anyone on the flight. Long 6 hr flight with no entertainment option and the staff didn’t know until an hour into the flight when we made sure they knew about it. They had no way to fix it.

Late FA meant slow boarding. WiFi did not work. I’m a medium plus sized passenger. The seatbelt was for the first time ever barely fitting. And we delayed on the tarmac 40 min

My husband and I had boarded the flight from Denver to Chicago, and one of the last passengers to get on the plane opened the overhead bin above my husband's seat and threw his bag out of the bin to make space for his own. He said, "Mine is bigger!" The flight attendant supported the new passenger. They didn't care that my husband has two artificial knees and must have the foot room in front of his seat to be able to fit his legs in -- and to be able to stand, much less walk, at the end of the flight. I have never seen this happen before, and it was a disaster.

one crew said "he" didn't serve double alcohol drinks for travelers in exit rows. crew on prior flight did. Is this a AA rule, and the prior crew was being nice? Also, I think we deserve more than a 25% refund for losing first class seats when rescheduling a flight due to weather

Amazing I love American. I’ll never fly anyone else if I can help it.

Experience was good. We were delayed in leaving by 15 mins because the flight was waiting on a family that was late in getting to the gate. Food and drink options were as expected. I highly recommend checking in ahead of time using the airline’s app so that it’s quicker to get your luggage tags as soon as you arrive at the terminal. No more waiting in long lines!

The captain brought my 6 year old son into the cockpit and allowed him to ask questions, sit in the captain’s chair and talk about all the gears and levers. Made the trip very special for him.

Better service. No food options, but we did get drinks and a cookie.

it was fine, decent flight... dont get food besides cookies or pretzels so not sure why you ask about food. same for entertainment..

Liked that it was on time. Staff professional and friendly.

More choices on snacks. Built-in video screen to enjoy entertainment choices.

Loved the crew . Absolutely no complaints. Except for luggage lost

this plane was really old, had exit row seats and tray was in arm of seat so super uncomfortable to use. another seat they could t even use the tray it was broke. seat i. front of me had duct tape on it cause seat was ripped open... this plane should either be updated or retired.

Good for a budget airline! It was easy to get on, staff was really nice. Can’t say anything about the food or entertainment because it wasn’t available, which is fine.

It was costly and difficult to check in. $85 to take a small suitcase with me, carry on or checked and $75 on the return trip, Plus $25 if I didn't check my self in check in $25, because I couldn't do it on the kiosk. Small very uncomfortable seats, waited on the runway for near an hour each way. It was my worst flight to date.

Due to weather, my flight was delayed, further delayed, then canceled. I eventually got through to a support person who helped me find a different route out of MSP, but to get to DIA, they didn't want to, but eventually did help with the connection ticket purchase. But even this replacement flight was delayed time and time again, and I would have missed my connecting flights and I didn't want to get stuck in a layover city, so after 12 hours at the airport with two young boys who were very tired, we just cancelled our plans and spent the week at home, instead of Nana's.

Horrible. I would never fly Frontier again. The booking process is tricky at best, but fraudulent in my opinion. Frontier customer service did nothing to rectify my purchase -- I ended up paying more than double what I could have gotten from other airlines and nearly triple what I thought I was buying from Frontier. Their booking practices are unfair to the consumer.

I knew going into this that Frontier, being a low cost carrier, would be pretty bare bones and charge for most extras but this was made up for by the fact that the airplane was a reasonably new Airbus, every employee was great and best of all, Everett Washington is an amazing airport - thanks Frontier for flying there!!!

I think Frontier was very good at communication. Their app worked very well. Loading was great and the flight was nice and easy.

Seats were new and comfortable. Staff was fine. Missed my connection due to weather -which wasn’t their fault- but got no help at all. Gate staff sent me to customer service, which was and stayed unstaffed. Sign with QR code directed me to call or chat. Chat was useless. Call was returned after an hour. No itinerary offered by Frontier could get me home in less than 30 hours. Rebooked with another airline and got a partial refund that came to about 10 percent of what I paid to get home.

The experience was good. No frills but I got there safe and sound and on time.

As every law enforcement agency I could imagine surrounded the plane and we didn’t disembark for 2 hours and then had to stick around for another hour to go get our personal belongings after leaving them behind and being bused away from the plane, it was scary and inconvenient. We were given no information as to why this was happening. Lack of communication with passengers was disappointing.

Frontier Airlines was AWFUL. I was an hour early for my flight and the lady refused to check me in. I had to purchase a whole new ticket with a different airline.

Everything you need to know for your flight from Phoenix to Boulder

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