$93 Find Cheap Flights from Philadelphia 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 Philadelphia to Boulder departing on 3/15. 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.
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1 adult, Economy, 0 bags

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Flight Deals

Cheap Flights from Philadelphia to Boulder (PHL-DEN)

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Philadelphia 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 Philadelphia to Boulder

Mon, Apr 6 - Mon, Apr 20
Frontier Logo
8:36 pm - 11:04 pm
PHL
-
DEN
4h 28mnonstop
Frontier Logo
11:59 pm - 9:11 am
DEN
-
PHL
7h 12m
1 stop
$170Frontier
Tue, Apr 7 - Fri, Apr 17
Frontier Logo
3:33 pm - 11:09 pm
PHL
-
DEN
9h 36m
1 stop
Frontier Logo
11:59 pm - 11:02 am
DEN
-
PHL
9h 03m
1 stop
$171Frontier
Mon, Apr 6 - Mon, Apr 20
Frontier Logo
8:36 pm - 11:04 pm
PHL
-
DEN
4h 28mnonstop
Frontier Logo
11:59 pm - 9:11 am
DEN
-
PHL
7h 12m
1 stop
$172Frontier
Thu, Mar 26 - Wed, Apr 1
Frontier Logo
6:10 am - 9:45 pm
PHL
-
DEN
17h 35m
1 stop
Frontier Logo
11:56 pm - 5:31 am
DEN
-
PHL
3h 35mnonstop
$173Frontier
Wed, Apr 1 - Mon, Apr 6
Frontier Logo
8:25 pm - 10:53 pm
PHL
-
DEN
4h 28mnonstop
Frontier Logo
11:56 pm - 5:31 am
DEN
-
PHL
3h 35mnonstop
$174Frontier
Fri, May 15 - Mon, May 18
Frontier Logo
8:25 pm - 10:53 pm
PHL
-
DEN
4h 28mnonstop
Frontier Logo
11:59 pm - 5:34 am
DEN
-
PHL
3h 35mnonstop
$175Frontier
Wed, Mar 11 - Fri, Mar 20
Frontier Logo
12:04 pm - 8:55 pm
PHL
-
DEN
10h 51m
1 stop
Frontier Logo
11:59 pm - 5:31 am
DEN
-
PHL
3h 32mnonstop
$176Frontier
Wed, Mar 25 - Mon, Mar 30
Frontier Logo
3:05 pm - 11:13 pm
PHL
-
DEN
10h 08m
1 stop
Frontier Logo
11:59 pm - 10:59 am
DEN
-
PHL
9h 00m
1 stop
$177Frontier
Sat, Mar 14 - Wed, Mar 18
Frontier Logo
6:00 am - 9:45 pm
PHL
-
DEN
17h 45m
1 stop
Frontier Logo
11:49 pm - 1:15 am
DEN
-
PHL
23h 26m
1 stop
$178Frontier
Mon, Apr 6 - Sat, Apr 11
Frontier Logo
7:41 pm - 9:40 am
PHL
-
DEN
15h 59m
1 stop
Frontier Logo
10:20 am - 8:51 pm
DEN
-
PHL
8h 31m
1 stop
$179Frontier
Useful Info

Good to know

Low seasonJanuary
Cheapest flight$93
Best time to beat the crowds with an average 1% drop in price.
Most popular time to fly and prices are also 13% lower on average.
Flight from Philadelphia to Denver

When to book flights from Philadelphia to Boulder

Are your dates flexible? Find out the best times to travel from Philadelphia 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 Philadelphia to Boulder

  • Which airports will I be using when flying from Philadelphia to Boulder?

    When flying out of Philadelphia you’ll be using Philadelphia. 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 Philadelphia to Boulder take?

    Direct flights cover the 1,553 miles separating Philadelphia and Boulder in about 4h 10m.

  • How many flights are there between Philadelphia and Boulder?

    16 direct flights run between Philadelphia and Boulder on a daily basis. On average, there are about 112 departures each week.

  • What’s the cheapest day of the week to fly between Philadelphia and Boulder?

    Consider leaving on a Sunday and avoid Saturdays if you are looking for the best rates. For your return to Philadelphia, you’ll find the best rates on Sundays and the most expensive ones on Fridays.

  • How does KAYAK find such low prices on flights from Philadelphia 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 Philadelphia to Boulder.

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

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to Boulder from Philadelphia 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 Philadelphia 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 Philadelphia with another airline.

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

    In the last 72 hours, the cheapest one-way ticket between Philadelphia and Boulder found on KAYAK was with Frontier for $64. Allegiant Air offered a round-trip connection from $106 and Frontier from $113.

Top tips for finding cheap flights from Philadelphia to Boulder

  • There is no airport in Boulder. Instead, you’ll be flying into Denver Airport when flying between Philadelphia and Boulder.
  • The cheapest flight from Philadelphia to Boulder was found 32 days before departure, on average.
  • Book at least 1 week before departure in order to get a below-average price.
  • High season is considered to be November, December and January. The cheapest month to fly is July.

Reviews of the top 5 airlines serving Philadelphia to Boulder

 
Need help choosing which airline to fly with from Philadelphia 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 4300 reviews
7.5Entertainment
8.0Comfort
8.6Crew
8.1Boarding
7.0Food
Airline reviews

I have not flown Southwest in awhile and had a very pleasant experience. From ticketing to boarding to the flight. The flight left on time and landed ahead of schedule. It won't be so long next time!!

10.0 ExcellentTy&Steph, Feb 2026
CLT - STL
Read more Southwest reviews

I have not flown Southwest in awhile and had a very pleasant experience. From ticketing to boarding to the flight. The flight left on time and landed ahead of schedule. It won't be so long next time!!

The Southwest experience has definitely taken a dive from its early days. You can no longer deferentiate from other airlines. Air travel is too expensive. Southwest is no longer budget friendly. They have lost me as a loyal customer.

Flight was hours late, unable to sit next to spouse, I have had so much better experiences. Substantially better, only saving grace was that it was a short flight.

An entire day of delays. Cost lots of money. Meals and a hotel.

The WiFi and crew on the plane were good, however, the boarding experience was awful. I paid for the Choice Preferred and was boarded in group 5 so all overhead storage was full. They found room for our luggage, but further back making getting off the plane a nightmare. Also, we were in row 6 and the seats were extremely uncomfortable. Both my daughter and I had no leg room and couldn’t wait to get off the plane.

The charges were ridiculous for an hour flight and the turbulence was very scary.

Still need to work out the kinks on the new assigned seating boarding process. Otherwise, a very good flight.

WiFi did not work. Boarding with the new seating assignments took too long. The temperature in the terminal was obnoxious. +/- 80°

The seats are now more narrow. I paid for front row the seats in the front are even more narrow than before.

Only downside was the legroom and seat width, which is always a problem unless I spend more for a premium seat.

2+hrs delay without any reason provided and a cramped flight

We waited an hour on the runway to get a gate in Orlando

Flight was delayed by 3-hours and their fix was… complimentary pretzels.

Flight was delayed due to crew being not on time

Flight crew issues delayed my flight by 2 1/2 hours. Causing me to miss my connection.

The staff on board and gate was nice - a welcome change from the usual. We also arrived early, which was a great benefit, given that it takes 30 minutes plus to get bags at SRQ.

The staff was frielndly. The plane was terrible, it was too small and should be decommissioned. There were no back seat screens at all. The only beverages we had a choice from was coffee, tea or water. The only bathroom in the back was behind the flight attendant's jump seat and wasn't working. And I literally felt like I was sitting on top of the guy next to me. It was terribly hot in the plane and we had to sit on the tarmac in Chicago for 1/2 hour due to congestion in Mpls. Wouldn't they have know that before they even boarded us so that we could have sat in comfort in the terminal?

Never got on it. Was re-routed through Detroit and am still in airports 12 hours later waiting for my connecting plane to arrive.

Delta has too many delays now days. It is 1:06 am now. I was supposed to land in Norfolk at 10:30 pm. I got re-booked through Detroit and I’m still in Detroit. I hope to be landed in Norfolk by 3am. I’ve been in airports for 12 hours as of right now. There is a weather delay now but most delays lately have been maintenance.

Very Very late. Subsequent flights left an hour before ours

Women boarding passengers at the gate was absolutely rude and disrespectful of passengers. The flight attendant was absolutely delightful! Smiling and connected with the passengers. So happy. The seats are cramped and uncomfortable but I guess that’s just the way it is Communication regarding flight was excellent

As great a red-eye flight as red-eye flights can be.

Both of my flights arrived early and check in process was smooth

Everything was on time Will use united again for sure

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

My husband and I recently had an unfortunate experience with Lufthansa. At the Philadelphia International airport, the ground staff refused to board us because we didn’t have a current visa stamped on our passports for Frankfurt. We completely understand that this was our mistake. we should have double-checked the visa requirements before our trip. However, the issue that upset us most was how the situation was handled by the staff. They told us they would mark it as “boarding denied due to visa issue”, but instead they recorded it as “no show”. Because of that incorrect entry, our return flight was automatically cancelled as well, which caused additional stress and expense. Mistakes can happen, but we expected more transparency and accuracy from a reputed airline like Lufthansa. It would have made a big difference if the staff had been more careful and considerate in documenting the situation correctly.

Beverage service was not good. Also just one service in 5 hr 30 min flight. No ask fir water ir anything beside one time beverage service.

They are always late and seats was also not having working charger

This flight captain and crew were amazing, started ahead of time of departure and reached 30 mins before arrival time. Amazing!

Long delays, lack of information about the status of the flight. The flight was delayed 4 times.

Everything about the flight was lovely. My only suggestion would be to offer a few more options of tv series from Apple TV or HBO.

Delays to take off and to leave the plane after landing added a lot of time to this flight.

The Phildalphia to Allentown portion was a BUS, not a plane. All was as expected.

Excellent - explanations were clear staff was nice and flight was comfortable

Flight was delayed not sure why no explanation given and no apologies either. Otherwise the flight was fine

Did not get the seat I selected and paid for.

First of all we hade waited 3 hours in the airplane waiting to leave. Second the return schedule was changed and it messed up my entire vaction. I won't buy never again another flight and recommend to nobody traveling with them.

I am writing to express my disappointment with my recent Frontier Airlines flight. I was charged $99 at the gate because my bag was said to be too large, yet once onboard there was no available overhead bin space, and I was required to place the bag under the seat in front of me anyway. This made the charge feel unnecessary and unfair. Additionally, before the flight even took off, I was asked to move from the seat I paid for into a middle seat so another passenger and her cat could have my seat to themselves. I was not offered compensation or an explanation for being moved from a paid seat. Between the unexpected bag fee and being forced to give up my seat, this experience fell well below acceptable customer service standards. I would appreciate a review of this situation and appropriate compensation.

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.

Terrible. Flight cancelled with no reasoning and no flights to rebook. Employees were useless and did nothing to help. Did not even know where to retrieve luggage from the cancelled flight. Flyers beware.

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!!!

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.

sluggish boarding and arrival procedures, fake nice flight attendants, and lots of delays.

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.

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

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