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$91+ 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 2/26. Fares are subject to change and may not be available on all flights or dates of travel.
PHL — DEN
Jan 26 — Feb 21
Sun 1/26
Sun 2/2
1 adult, Economy
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The best prices from Philadelphia to Boulder are usually found in April 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

Discover tips and strategies to find the most affordable flight options for your journey from Philadelphia (PHL) to Boulder (BD9). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated January 21, 2025.

Round-trip from

$168
(Cheapflightsfares)

One-way from

$92
(Trip.com)

Popular in

December

Cheapest in

April

Average price

$314
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. 11% potential increase in price ($38 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 January 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 January 21, 2025.

This Cheapflightsfares deal was found by Cheapflights users on 1/20. 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.
Fri 2/216:45 amPHL - DEN
1 stop17h 04mFrontier
Sun 2/236:00 amDEN - PHL
Nonstop3h 39mFrontier
Deal found 1/20$168
This FlightHub deal was found by Cheapflights users on 1/21. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 2/151:27 pmPHL - DEN
1 stop8h 05mMultiple Airlines
Thu 2/206:50 pmDEN - PHL
1 stop13h 26mMultiple Airlines
Deal found 1/21$185
This American Airlines deal was found by Cheapflights users on 1/20. 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.
Wed 3/57:10 pmPHL - DEN
Nonstop4h 40mAmerican Airlines
Mon 3/1012:20 amDEN - PHL
Nonstop3h 22mAmerican Airlines
Deal found 1/20$188
This Southwest deal was found by Cheapflights users on 1/19. 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.
Sat 2/224:55 pmPHL - DEN
Nonstop4h 25mSouthwest
Tue 2/255:45 pmDEN - PHL
Nonstop3h 30mSouthwest
Deal found 1/19$233
This Delta deal was found by Cheapflights users on 1/19. 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.
Wed 3/196:59 pmPHL - DEN
1 stop6h 05mDelta
Tue 3/2512:55 amDEN - PHL
1 stop6h 26mDelta
Deal found 1/19$257
This JetBlue deal was found by Cheapflights users on 1/21. 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.
Fri 3/286:00 amPHL - DEN
1 stop8h 09mJetBlue
Mon 3/3110:35 pmDEN - PHL
1 stop7h 04mJetBlue
Deal found 1/21$263
This Sun Country Air deal was found by Cheapflights users on 1/21. 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 Sun Country Air is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 7/412:05 pmPHL - DEN
1 stop8h 10mSun Country Air
Thu 7/1010:20 amDEN - PHL
1 stop22h 50mSun Country Air
Deal found 1/21$290
This United Airlines deal was found by Cheapflights users on 1/21. 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.
Tue 2/45:10 pmPHL - DEN
1 stop6h 48mUnited Airlines
Sat 2/85:50 pmDEN - PHL
Nonstop3h 34mUnited Airlines
Deal found 1/21$315

Find flights from Philadelphia to Boulder within your budget

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 January 21, 2025.

Fly from

Any airport

Fly to

Any airport

Route

Depart

Return

Price

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Fri 2/21

6:45 am-9:49 pm

1 stop17h 04m

Denver Intl

Sun 2/23

6:00 am-11:39 am

Nonstop3h 39m

$168

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Sat 2/15

1:27 pm-7:32 pm

1 stop8h 05m

Denver Intl

Thu 2/20

6:50 pm-10:16 am

1 stop13h 26m

$185

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Wed 3/5

7:10 pm-9:50 pm

Nonstop4h 40m

Denver Intl

Mon 3/10

12:20 am-5:42 am

Nonstop3h 22m

$188

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Sat 2/22

4:55 pm-7:20 pm

Nonstop4h 25m

Denver Intl

Wed 2/26

5:45 pm-11:15 pm

Nonstop3h 30m

$233

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Wed 3/19

6:59 pm-11:04 pm

1 stop6h 05m

Denver Intl

Tue 3/25

12:55 am-9:21 am

1 stop6h 26m

$257

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Fri 3/28

6:00 am-12:09 pm

1 stop8h 09m

Denver Intl

Mon 3/31

10:35 pm-7:39 am

1 stop7h 04m

$263

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Fri 7/4

12:05 pm-6:15 pm

1 stop8h 10m

Denver Intl

Thu 7/10

10:20 am-11:10 am

1 stop22h 50m

$290

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Tue 2/4

3:40 pm-6:02 pm

Nonstop4h 22m

Denver Intl

Sat 2/8

5:50 pm-11:24 pm

Nonstop3h 34m

$305

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Wed 2/26

8:26 am-8:06 pm

2 stops13h 40m

$91

PhiladelphiaDenver

PHL - DEN

PHLDEN

Philadelphia

Tue 2/11

9:45 am-12:10 pm

Nonstop4h 25m

$96

Flights are sorted by cheapest round-trip flights first.

Deals found on 1/20

Showing 1-10 of 16 results
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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.

Travel insights for flights from Philadelphia to Boulder

Get recent, data-driven insights about flights from Philadelphia to Boulder including ideal travel times, pricing trends, and more.

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 January 17, 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 January 21, 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 Tuesday evenings when fares are most often at their lowest. Monday mornings 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 January 21, 2025.

The most flights from PHL to BD9 are scheduled on a Monday (13 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (8 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 January 21, 2025.
Read reviews from past customers who have flown United Airlines, Frontier and American Airlines 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
4,662 reviews

Food

7.2

Entertainment

7.7

Boarding

8.2

Comfort

8.1

Crew

8.7

Overall

8.1

Reviews

1 / 10

We BARELY made the connection and when we got onboard we were treated like disobedient children who should have arrived earlier because we had to ask other passengers to move so we could sit with our kids. The flight attendants on the first flight were nice but the second one, they were snippy and fairly rude.

Southwest
8.1
Very good
4,662 reviews
Southwest
8.1
Very good
4,662 reviews

Food

7.2

Entertainment

7.7

Boarding

8.2

Comfort

8.1

Crew

8.7

Overall

8.1

Reviews

1 / 10

We BARELY made the connection and when we got onboard we were treated like disobedient children who should have arrived earlier because we had to ask other passengers to move so we could sit with our kids. The flight attendants on the first flight were nice but the second one, they were snippy and fairly rude.

Alaska Airlines
8.0
Very good
9,706 reviews
Southwest
8.1
Very good
4,662 reviews

Food

7.2

Entertainment

7.7

Boarding

8.2

Comfort

8.1

Crew

8.7

Overall

8.1

Reviews

1 / 10

We BARELY made the connection and when we got onboard we were treated like disobedient children who should have arrived earlier because we had to ask other passengers to move so we could sit with our kids. The flight attendants on the first flight were nice but the second one, they were snippy and fairly rude.

Delta
8.0
Very good
8,521 reviews
Southwest
8.1
Very good
4,662 reviews

Food

7.2

Entertainment

7.7

Boarding

8.2

Comfort

8.1

Crew

8.7

Overall

8.1

Reviews

1 / 10

We BARELY made the connection and when we got onboard we were treated like disobedient children who should have arrived earlier because we had to ask other passengers to move so we could sit with our kids. The flight attendants on the first flight were nice but the second one, they were snippy and fairly rude.

JetBlue
7.4
Good
3,201 reviews
Southwest
8.1
Very good
4,662 reviews

Food

7.2

Entertainment

7.7

Boarding

8.2

Comfort

8.1

Crew

8.7

Overall

8.1

Reviews

1 / 10

We BARELY made the connection and when we got onboard we were treated like disobedient children who should have arrived earlier because we had to ask other passengers to move so we could sit with our kids. The flight attendants on the first flight were nice but the second one, they were snippy and fairly rude.

United Airlines
7.4
Good
8,985 reviews
Southwest
8.1
Very good
4,662 reviews

Food

7.2

Entertainment

7.7

Boarding

8.2

Comfort

8.1

Crew

8.7

Overall

8.1

Reviews

1 / 10

We BARELY made the connection and when we got onboard we were treated like disobedient children who should have arrived earlier because we had to ask other passengers to move so we could sit with our kids. The flight attendants on the first flight were nice but the second one, they were snippy and fairly rude.

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 8 different airlines.

  • How popular is this Philadelphia to Boulder flight route?

    This flight path from Philadelphia to Boulder was viewed by 165 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 $92. Users have also found prices from $105 and $116 on JetBlue 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 Frontier (85%), Air Canada (85%) and Southwest (76%).

  • What are the cheapest flights from Philadelphia to Boulder?

    On average you can expect to pay $818 for a flight from Philadelphia to Boulder. The cheapest flight overall is $90 while the most popular route, (Philadelphia - Denver Intl) is currently priced at $125.

  • 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.

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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 8 airlines flying from Philadelphia to Boulder

Discover the top 8 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 January 21, 2025.
AirlineCheapestAverageFlexibilityOn-time
Sun Country AirCheapest$82Average$275FlexibilityNo cancel feeOn-time83%
FrontierCheapest$88Average$205FlexibilityNo cancel feeOn-time62%
Allegiant AirCheapest$130Average$238FlexibilityNo cancel feeOn-time88%
SouthwestCheapest$182Average$408FlexibilityNo cancel feeOn-time63%
United AirlinesCheapest$187Average$503FlexibilityNo cancel feeOn-time69%
American AirlinesCheapest$189Average$422FlexibilityNo cancel feeOn-time71%
JetBlueCheapest$207Average$325FlexibilityNo cancel feeOn-time62%
DeltaCheapest$221Average$388FlexibilityNo cancel feeOn-timeN/A
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