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$73+ Cheap flights from St. Louis to Philadelphia (STL - PHL)

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 9/22. Fares are subject to change and may not be available on all flights or dates of travel.
STL — PHL
Aug 23 — Aug 301
Sat 8/23
Sat 8/30
1 adult, Economy
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Cheapflights Tip: The best prices from Lambert-St Louis to Philadelphia are usually found in August or September, booked 68 days in advance, depart on a Thursday or Friday and return on a Wednesday

Cheap flight deals from St. Louis to Philadelphia

Discover tips and strategies to find the most affordable flight options for your journey from St. Louis (STL) to Philadelphia (PHL). 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 August 18, 2025.

Round-trip from

$144
(Priceline)

One-way from

$73
(Priceline)

Popular in

March

Cheapest in

August

Average price

$275

Good round-trip deal

$417 or less

Good one-way deal

$235 or less
From Lambert-St Louis to Philadelphia
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One-way flight from Lambert-St Louis to Philadelphia
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Highest demand for flights based on searches. 6% potential increase in price ($29 potential increase over avg. RT price).
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Cheapest flight prices on average. 1% potential price decrease ($5 potential savings vs. average RT price).
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Average for round-trip flights in August 2025
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Price to beat on a round-trip flight from Lambert-St Louis to Philadelphia.
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Price to beat on a one-way flight from Lambert-St Louis to Philadelphia.
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Find flight deals from St. Louis to Philadelphia

Cheapest flights from St. Louis to Philadelphia
Explore the most affordable flight options available from St. Louis to Philadelphia. Find the lowest fares from popular airlines and budget airlines, with prices last updated on August 18, 2025.

This Priceline deal was found by Cheapflights users on 8/17. 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.
Fri 9/51:57 pmSTL - PHL
1 stop6h 14mFrontier
Sun 9/75:15 amPHL - STL
1 stop8h 52mFrontier
Deal found 8/17$144
This Frontier deal was found by Cheapflights users on 8/16. 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.
Fri 9/51:57 pmSTL - PHL
1 stop6h 14mFrontier
Thu 9/115:15 amPHL - STL
1 stop10h 49mFrontier
Deal found 8/16$153
This FlightHub deal was found by Cheapflights users on 8/17. 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.
Thu 9/114:00 pmSTL - PHL
1 stop25h 34mFrontier
Sun 9/146:30 pmPHL - STL
1 stop19h 32mFrontier
Deal found 8/17$160
This Frontier deal was found by Cheapflights users on 8/16. 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.
Wed 9/37:54 pmSTL - PHL
1 stop8h 00mFrontier
Sun 9/75:15 amPHL - STL
1 stop10h 49mFrontier
Deal found 8/16$163
This FlightHub deal was found by Cheapflights users on 8/17. 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.
Thu 10/2311:32 amSTL - PHL
1 stop12h 22mFrontier
Sun 10/268:15 amPHL - STL
1 stop26h 17mFrontier
Deal found 8/17$166
This CheapOair deal was found by Cheapflights users on 8/16. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/410:49 amSTL - PHL
1 stop28h 43mFrontier
Wed 9/102:45 pmPHL - STL
1 stop25h 19mFrontier
Deal found 8/16$169
This FlightHub deal was found by Cheapflights users on 8/16. 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.
Wed 9/37:54 pmSTL - PHL
1 stop8h 00mFrontier
Sat 9/66:37 pmPHL - STL
1 stop21h 27mFrontier
Deal found 8/16$170
This FlightHub deal was found by Cheapflights users on 8/17. 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.
Fri 10/176:05 pmSTL - PHL
1 stop6h 02mFrontier
Mon 11/36:19 amPHL - STL
1 stop27h 48mFrontier
Deal found 8/17$171
This Kiwi.com deal was found by Cheapflights users on 8/16. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 9/74:00 pmSTL - PHL
1 stop17h 56mFrontier
Thu 9/115:15 amPHL - STL
1 stop10h 49mFrontier
Deal found 8/16$178
This Kiwi.com deal was found by Cheapflights users on 8/16. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/44:00 pmSTL - PHL
1 stop7h 57mFrontier
Thu 9/115:15 amPHL - STL
1 stop10h 49mFrontier
Deal found 8/16$180
This Priceline deal was found by Cheapflights users on 8/16. 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.
Fri 10/106:05 pmSTL - PHL
1 stop6h 02mFrontier
Sun 10/1211:45 amPHL - STL
1 stop6h 25mFrontier
Deal found 8/16$181
This FlightHub deal was found by Cheapflights users on 8/17. 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.
Sun 9/144:00 pmSTL - PHL
1 stop17h 56mFrontier
Sun 9/216:30 pmPHL - STL
1 stop19h 32mFrontier
Deal found 8/17$182

Cheapflights Fare Finder

 
Customize your flight search to find flights from St. Louis to Philadelphia 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 18, 2025.
Use the filters below to find and compare flights from St. Louis to Philadelphia that are best for you.

Fly from

St. Louis

Fly to

Philadelphia

Route

Depart

Return

Price

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Fri 9/5

1:57 pm-9:11 pm

1 stop6h 14m

Philadelphia

Sun 9/7

5:15 am-1:07 pm

1 stop8h 52m

$144

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Thu 9/18

4:00 pm-12:57 am

1 stop7h 57m

Philadelphia

Mon 9/22

5:15 am-1:02 pm

1 stop8h 47m

$144

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Thu 9/4

4:00 pm-12:57 am

1 stop7h 57m

Philadelphia

Mon 9/8

5:15 am-1:02 pm

1 stop8h 47m

$153

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Fri 9/5

1:57 pm-12:52 am

1 stop9h 55m

Philadelphia

Mon 9/8

5:15 am-3:04 pm

1 stop10h 49m

$153

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Mon 9/22

1:57 pm-12:52 am

1 stop9h 55m

Philadelphia

Thu 9/25

5:15 am-3:04 pm

1 stop10h 49m

$153

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Sun 9/7

4:00 pm-12:57 am

1 stop7h 57m

Philadelphia

Mon 9/8

5:15 am-1:02 pm

1 stop8h 47m

$153

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Thu 10/2

4:00 pm-12:57 am

1 stop7h 57m

Philadelphia

Mon 10/6

8:30 am-8:37 pm

1 stop13h 07m

$153

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Fri 9/5

1:57 pm-9:11 pm

1 stop6h 14m

Philadelphia

Thu 9/11

5:15 am-3:04 pm

1 stop10h 49m

$153

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Mon 10/20

6:05 pm-1:07 am

1 stop6h 02m

$73

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Thu 10/30

11:07 am-6:44 pm

1 stop6h 37m

$73

Flights are sorted by cheapest round-trip flights first.

Deals found on 8/16

Showing 1-10 of 15 results
1
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The best insider tips for St. Louis to Philadelphia flights

Snippets provided in this section are AI-generated based on a summarization of Cheapflights-commissioned articles. The articles are presented as-is, for general informational purposes only, and may not be up-to-date. The opinions contained in the articles are original to the author and reflect their authentic experience, which may vary significantly from the experience of others.
Cheapflights partnered with top experts to bring you the best recommendations for your St. Louis to Philadelphia trip
Airports
STL

Expect security screening at STL to take 5-10 minutes during off-peak times. Check real-time wait times online before heading to the airport.

Read more about STLby Taryn White
PHL

For a quick trip to Center City, take the SEPTA Airport Line. It's efficient and operates between 5:00 a.m. and midnight.

Read more about PHLby Mark Chesnut
Our travel experts
Mark Chesnut

Mark Chesnut

Expert on PHL

Mark Chesnut

Mark Chesnut

Mark Chesnut is a travel writer and public speaker with more than 30 years of experience. The 2019 winner of the NLGJA Excellence in Travel Writing Award, Mark is the author of the book “Prepare for Departure” and has covered air travel for multiple top consumer and trade media outlets.

Read more
Taryn White

Taryn White

Expert on STL

Taryn White

Taryn White

Taryn White is a freelance travel writer, digital creator, and travel advisor who has visited nearly 100 countries and all 50 states. She’s familiar with many airports and enjoys beach hopping, boutique hotels, spa experiences, and exploring local culture. Her work has appeared in Travel + Leisure, Condé Nast Traveler, National Geographic, Smithsonian Magazine, AFAR, and more.

Read more

Best time to book a flight from St. Louis to Philadelphia

Have a flexible travel schedule? Discover the best time to fly to Philadelphia from St. Louis 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 St. Louis to Philadelphia

How far ahead should I book a flight from St. Louis to Philadelphia?

Use this chart to determine the optimal time to book a round-trip flight from St. Louis to Philadelphia. Price data was last updated on August 8, 2025.

The price you pay for your flight from St. Louis to Philadelphia may vary depending on when you book. For the best chance of a lower fare, look to book 68 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.

What is the cheapest month to book a flight from St. Louis to Philadelphia?

Currently, August is the cheapest month in which you can book a flight from St. Louis to Philadelphia (average of $236). Flying from St. Louis to Philadelphia in March is currently the most expensive (average of $295). 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 STL to PHL?

Find hourly flight availability from St. Louis to Philadelphia. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated August 18, 2025.

It’s typically best to fly out from St. Louis to Philadelphia in the evening. Doing so could potentially save you 65% on the flight price compared to flying at noon, which is usually more expensive.

What is the cheapest day to fly from St. Louis to Philadelphia?

Use this chart to determine the cheapest time to fly round-trip from St. Louis to Philadelphia. Price data was last updated on August 10, 2025.

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

Weekly flight availability from St. Louis to Philadelphia

Explore weekly flight availability from St. Louis to Philadelphia. 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 18, 2025.

The most flights from STL to PHL are scheduled on a Sunday (12 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (5 on average).

Reviews of airlines servicing Philadelphia

Get insights into the airlines that provide service to Philadelphia. 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 Philadelphia. Reviews last updated August 18, 2025.
Read reviews from past customers who have flown Southwest, Delta, and American Airlines from St. Louis to Philadelphia. Users can see the overall rating for each airline as well as how each is rated in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.0
Very good
4,246 reviews

Food

7.0

Comfort

8.0

Entertainment

7.5

Overall

8.0

Boarding

8.1

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Southwest
8.0
Very good
4,246 reviews
Southwest
8.0
Very good
4,246 reviews

Food

7.0

Comfort

8.0

Entertainment

7.5

Overall

8.0

Boarding

8.1

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Delta
8.0
Very good
7,981 reviews
Southwest
8.0
Very good
4,246 reviews

Food

7.0

Comfort

8.0

Entertainment

7.5

Overall

8.0

Boarding

8.1

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
American Airlines
7.2
Good
10,000 reviews
Southwest
8.0
Very good
4,246 reviews

Food

7.0

Comfort

8.0

Entertainment

7.5

Overall

8.0

Boarding

8.1

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Spirit Airlines
6.3
Okay
8,038 reviews
Southwest
8.0
Very good
4,246 reviews

Food

7.0

Comfort

8.0

Entertainment

7.5

Overall

8.0

Boarding

8.1

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Frontier
5.8
Fair
3,212 reviews
Southwest
8.0
Very good
4,246 reviews

Food

7.0

Comfort

8.0

Entertainment

7.5

Overall

8.0

Boarding

8.1

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.

Related info for your journey

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

  • What airports do I use to fly from St. Louis to Philadelphia?

    Booking a flight from Lambert-St Louis (STL) to Philadelphia (PHL) is your only option if you wish to fly from St. Louis to Philadelphia. On a typical day, there are 9 flights from Lambert-St Louis to Philadelphia, all of which are around 2h 05m for a nonstop flight. You can also purchase a plane ticket from 5 airlines when you book a flight from Lambert-St Louis to Philadelphia.

  • How popular is this St. Louis to Philadelphia flight route?

    Within the past month, 14 users have taken a look at flights from Lambert-St Louis to Philadelphia.

  • What are the cheapest airlines flying from St. Louis to Philadelphia round-trip?

    Cheapflights users have booked flights from St. Louis to Philadelphia round-trip from $106. Other airlines that can offer you cheap pricing are Frontier, from $128, and Delta, from $208. These flights start at 72% lower than the current average price 3 months from now.

  • What are the most reliable airlines from St. Louis to Philadelphia?

    No one likes to see their flight delayed. When booking a flight from St. Louis to Philadelphia consider choosing Southwest (79%), Qatar Airways (70%) or Aer Lingus (64%) as they are the most reliable in getting you off to your destination on time.

  • What are the cheapest flights from St. Louis to Philadelphia?

    While on average a flight from St. Louis to Philadelphia is generally $1,428, our data shows the cheapest flight currently is $118. When looking at the most popular route, (Lambert-St Louis - Philadelphia), you can expect to pay $170 for that flight.

  • Can I find deals for flights from St. Louis to Philadelphia that include hotel bookings?

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

  • How can I find direct flights from St. Louis to Philadelphia?

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

  • Can I find deals for business class flights from St. Louis to Philadelphia?

    Yes. Cheapflights offers flight deals from St. Louis to Philadelphia 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 St. Louis to Philadelphia?

    Currently, August is the cheapest month in which you can book a flight from St. Louis to Philadelphia (average of $236). Flying from St. Louis to Philadelphia in March is currently the most expensive (average of $295). 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

Traveling to a place near Philadelphia?

Book flights to Philadelphia if you plan to visit one of these locations
Vineland
Wildwood
King of Prussia
Pottstown
Cherry Hill
Ocean City
Reading
Millville
Ephrata
Camden
Dewey Beach
Dover
Elkton
Essington
Willow Grove
Newark
Chester
Exton
Glen Mills
Springfield

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Alternative routes for St. Louis to Philadelphia

See prices for flight routes from nearby airports that may be better suited for you.
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Top 5 airlines flying from St. Louis to Philadelphia

Discover the top 5 airlines that operate flights from St. Louis to Philadelphia. 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 18, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$68Average$214FlexibilityNo cancel feeOn-time62%
Spirit AirlinesCheapest$82Average$189FlexibilityNo cancel feeOn-time65%
DeltaCheapest$208Average$417FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$221Average$408FlexibilityNo cancel feeOn-time71%
SouthwestCheapest$281Average$410FlexibilityNo cancel feeOn-time63%

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