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$85+ Cheap flights from Philadelphia (PHL) 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 4/8. Fares are subject to change and may not be available on all flights or dates of travel.
PHL — DEN
Mar 31 — Apr 71
Mon 3/31
Mon 4/7
1 adult, Economy
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Cheapflights Tip: The best prices from Philadelphia to Boulder are usually found in September or May, booked 56 days in advance, depart on a Tuesday or Wednesday and return on a Wednesday

Cheap flight deals from Philadelphia to Boulder

Keep the following information in mind while searching for Philadelphia to Boulder flight deals. Data was last updated March 26, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$170
(Frontier)

One-way from

$85
(Mytrip)

Popular in

December

Cheapest in

September

Average price

$336
Provider with most accurate pricing for Philadelphia-Denver Intl flight deals.
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Provider most trusted by Cheapflights users for Philadelphia-Denver Intl flights.
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From Philadelphia to Boulder
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One-way flight from Philadelphia to Boulder
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Highest demand for flights based on searches. 8% potential increase in price ($27 potential increase over avg. RT price).
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Cheapest flight prices on average. 2% potential price decrease ($8 potential savings vs. average RT price).
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Average for round-trip flights in March 2025
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Find flight deals from Philadelphia to Boulder

Cheapest flights from Philadelphia to Boulder
Explore the most affordable flight options available from Philadelphia to Boulder. Find the lowest fares from popular airlines and budget airlines, with prices last updated on March 26, 2025.

This Frontier deal was found by Cheapflights users on 3/24. 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 4/76:40 amPHL - DEN
Nonstop4h 21mFrontier
Sat 4/1211:59 pmDEN - PHL
Nonstop3h 32mFrontier
Deal found 3/24$170
This American Airlines deal was found by Cheapflights users on 3/25. 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 5/27:55 pmPHL - DEN
Nonstop4h 11mAmerican Airlines
Tue 5/61:42 pmDEN - PHL
Nonstop3h 47mAmerican Airlines
Deal found 3/25$171
This Southwest deal was found by Cheapflights users on 3/24. 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 5/16:55 pmPHL - DEN
1 stop6h 10mSouthwest
Wed 5/75:30 pmDEN - PHL
Nonstop3h 35mSouthwest
Deal found 3/24$196
This Flightnetwork deal was found by Cheapflights users on 3/25. 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 Flightnetwork is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/2412:40 pmPHL - DEN
Nonstop4h 20mMultiple Airlines
Thu 5/16:30 pmDEN - PHL
1 stop14h 29mMultiple Airlines
Deal found 3/25$199
This United Airlines deal was found by Cheapflights users on 3/24. 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 5/2810:10 amPHL - DEN
Nonstop4h 07mUnited Airlines
Sat 5/3111:45 pmDEN - PHL
Nonstop3h 37mUnited Airlines
Deal found 3/24$207
This JetBlue deal was found by Cheapflights users on 3/24. 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 JetBlue is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/36:00 amPHL - DEN
1 stop9h 06mJetBlue
Sun 5/410:39 pmDEN - PHL
1 stop9h 01mJetBlue
Deal found 3/24$209
This Delta deal was found by Cheapflights users on 3/24. 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 5/27:25 pmPHL - DEN
1 stop6h 15mDelta
Mon 5/512:55 amDEN - PHL
1 stop5h 56mDelta
Deal found 3/24$257
This Gotogate deal was found by Cheapflights users on 3/24. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/712:05 pmPHL - DEN
1 stop8h 10mSun Country Air
Thu 8/147:15 pmDEN - PHL
1 stop13h 55mSun Country Air
Deal found 3/24$330

Cheapflights Fare Finder

Customize your flight search to find flights from Philadelphia 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 March 26, 2025.
Use the filters below to find and compare flights from Philadelphia to Boulder that are best for you.

Fly from

Philadelphia

Fly to

Boulder

Route

Depart

Return

Price

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Mon 4/7

6:40 am-9:01 am

Nonstop4h 21m

Denver Intl

Tue 4/15

11:50 pm-5:20 am

Nonstop3h 30m

$170

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Fri 5/2

7:55 pm-10:06 pm

Nonstop4h 11m

Denver Intl

Tue 5/6

1:42 pm-7:29 pm

Nonstop3h 47m

$171

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Thu 5/1

5:00 am-7:10 am

Nonstop4h 10m

Denver Intl

Tue 5/6

1:15 pm-10:10 pm

1 stop6h 55m

$196

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Wed 5/28

10:10 am-12:17 pm

Nonstop4h 07m

Denver Intl

Sat 5/31

11:45 pm-5:22 am

Nonstop3h 37m

$207

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Sat 5/3

6:00 am-1:06 pm

1 stop9h 06m

Denver Intl

Sun 5/4

10:39 pm-9:40 am

1 stop9h 01m

$209

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Mon 4/28

6:00 am-9:32 am

1 stop5h 32m

Denver Intl

Mon 5/5

3:35 pm-12:49 am

1 stop7h 14m

$257

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Sat 8/16

6:15 am-8:28 am

Nonstop4h 13m

Denver Intl

Thu 8/21

7:15 pm-11:15 am

1 stop14h 00m

$266

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Tue 4/8

6:40 am-9:01 am

Nonstop4h 21m

$85

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Sat 5/17

7:40 pm-9:53 pm

Nonstop4h 13m

$106

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Tue 7/22

3:39 pm-5:58 pm

Nonstop4h 19m

$113

Flights are sorted by cheapest round-trip flights first.

Deals found on 3/25

Showing 1-10 of 16 results
1
2

Best time to book a flight from Philadelphia to Boulder

Have a flexible travel schedule? Discover the best time to fly to Boulder from Philadelphia 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 Philadelphia to Boulder

How far ahead should I book a flight from Philadelphia to Boulder?

Use this chart to determine the optimal time to book a round-trip flight from Philadelphia to Boulder. Price data was last updated on March 21, 2025.

Booking 56 days in advance of your planned departure date is, on average, the best time to get cheap flights from Philadelphia to Boulder. The general trend is that the closer you book to the departure date, the more expensive your flight will be.

What is the cheapest month to book a flight from Philadelphia to Boulder?

Currently, October is the cheapest month in which you can book a flight from Philadelphia to Boulder (average of $197). Flying from Philadelphia 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 PHL to BD9?

Find hourly flight availability from Philadelphia 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 March 26, 2025.

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

What is the cheapest day to fly from Philadelphia to Boulder?

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

Travelers seeking maximum savings on their Philadelphia to Boulder flight should consider departing on Saturday evenings when fares are most often at their lowest. Saturday afternoons flights should be avoided if possible as fares are typically the most expensive at this time.

Weekly flight availability from Philadelphia to Boulder

Explore weekly flight availability from Philadelphia 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 March 26, 2025.

The most flights from PHL to BD9 are scheduled on a Monday (16 on average). You will have fewer flight options on Sunday, which is when the least amount of flights are scheduled (1 on average).

Rainfall in Boulder by month

Plan your trip to Boulder by taking into account the average rainfall totals by month.

In terms of precipitation, rainfall in Boulder ranges from 0.5 - 2.3 inches per month. May is typically the wettest month, when rainfall can reach 2.3 in. January is typically the driest time to visit Boulder when rainfall is around 0.5 in.

Temperature in Boulder by month

Plan your trip to Boulder by taking into account the average temperature totals by month.

If weather is an important factor for your trip to Boulder, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 73.4 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 30.2 F).

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 March 26, 2025.
Read reviews from past customers who have flown Southwest, Alaska Airlines and Delta from Philadelphia to Boulder. You can also see how each airline compares in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.1
Very good
4,273 reviews

Comfort

8.1

Food

7.1

Overall

8.1

Entertainment

7.6

Crew

8.6

Boarding

8.2

Reviews

1 / 20
8.0
Excellent

Ila,Mar 2025

HOU - DAL

Our original flight was delayed. We were able to change our flight and got home at close to the same time. Looking forward to when you have assigned seating.
Southwest
8.1
Very good
4,273 reviews
Southwest
8.1
Very good
4,273 reviews

Comfort

8.1

Food

7.1

Overall

8.1

Entertainment

7.6

Crew

8.6

Boarding

8.2

Reviews

1 / 20
8.0
Excellent

Ila,Mar 2025

HOU - DAL

Our original flight was delayed. We were able to change our flight and got home at close to the same time. Looking forward to when you have assigned seating.
Alaska Airlines
8.0
Very good
9,789 reviews
Southwest
8.1
Very good
4,273 reviews

Comfort

8.1

Food

7.1

Overall

8.1

Entertainment

7.6

Crew

8.6

Boarding

8.2

Reviews

1 / 20
8.0
Excellent

Ila,Mar 2025

HOU - DAL

Our original flight was delayed. We were able to change our flight and got home at close to the same time. Looking forward to when you have assigned seating.
Delta
8.0
Very good
7,891 reviews
Southwest
8.1
Very good
4,273 reviews

Comfort

8.1

Food

7.1

Overall

8.1

Entertainment

7.6

Crew

8.6

Boarding

8.2

Reviews

1 / 20
8.0
Excellent

Ila,Mar 2025

HOU - DAL

Our original flight was delayed. We were able to change our flight and got home at close to the same time. Looking forward to when you have assigned seating.
United Airlines
7.4
Good
8,608 reviews
Southwest
8.1
Very good
4,273 reviews

Comfort

8.1

Food

7.1

Overall

8.1

Entertainment

7.6

Crew

8.6

Boarding

8.2

Reviews

1 / 20
8.0
Excellent

Ila,Mar 2025

HOU - DAL

Our original flight was delayed. We were able to change our flight and got home at close to the same time. Looking forward to when you have assigned seating.
JetBlue
7.3
Good
2,922 reviews
Southwest
8.1
Very good
4,273 reviews

Comfort

8.1

Food

7.1

Overall

8.1

Entertainment

7.6

Crew

8.6

Boarding

8.2

Reviews

1 / 20
8.0
Excellent

Ila,Mar 2025

HOU - DAL

Our original flight was delayed. We were able to change our flight and got home at close to the same time. Looking forward to when you have assigned seating.

Related info for your journey

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

  • What airport do you fly from for flights from Philadelphia to Boulder?

    If you book a flight to Boulder from Philadelphia, you will be flying from Philadelphia, which is the city’s only airport. Philadelphia (PHL) is located 7.0 mi from the center of Philadelphia. There are 10 flights from Philadelphia to Boulder per day from 7 different airlines.

  • How popular is this Philadelphia to Boulder flight route?

    This flight path from Philadelphia to Boulder was viewed by 159 users in the past month. Keep an eye out for changes in search interest prior to high and low season.

  • What are the cheapest airlines to fly from Philadelphia to Boulder one-way?

    For one-way options, check prices for Frontier. According to our data, you can fly for as low as $85. Users have also found prices from $106 and $113 on American Airlines and United Airlines, respectively.

  • What are the most reliable airlines from Philadelphia to Boulder?

    The top 3 most reliable airlines when flying from Philadelphia to Boulder are Air Canada (88%), United Airlines (88%) and Qatar Airways (85%).

  • What are the cheapest flights from Philadelphia to Boulder?

    On average you can expect to pay $706 for a flight from Philadelphia to Boulder. The cheapest flight overall is $87 while the most popular route, (Philadelphia - Denver Intl) is currently priced at $141.

  • Can I find deals for flights from Philadelphia to Boulder that include hotel bookings?

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

  • How can I find direct flights from Philadelphia to Boulder?

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

  • Can I find deals for business class flights from Philadelphia to Boulder?

    Yes. Cheapflights offers flight deals from Philadelphia 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 Philadelphia to Boulder?

    Currently, October is the cheapest month in which you can book a flight from Philadelphia to Boulder (average of $197). Flying from Philadelphia 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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Alternative routes for Philadelphia to Boulder

See prices for flight routes from nearby airports that may be better suited for you.
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Top 7 airlines flying from Philadelphia to Boulder

Discover the top 7 airlines that operate flights from Philadelphia 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 March 26, 2025.
AirlineCheapestAverageFlexibilityOn-time
Sun Country AirCheapest$82Average$275FlexibilityNo cancel feeOn-time83%
FrontierCheapest$87Average$204FlexibilityNo cancel feeOn-time62%
American AirlinesCheapest$184Average$416FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$185Average$490FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$194Average$418FlexibilityNo cancel feeOn-time63%
JetBlueCheapest$207Average$325FlexibilityNo cancel feeOn-time62%
DeltaCheapest$215Average$380FlexibilityNo cancel feeOn-timeN/A
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