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$50+ 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 22 — Aug 291
Sat 8/22
Sat 8/29
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 85 days in advance, depart on a Friday or Thursday and return on a Wednesday

Cheap 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 July 23, 2026.

This Kiwi.com deal was found by Cheapflights users on 7/22. 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.
Mon 8/316:17 pm
STL
-
PHL
1 stop11h 58m
Frontier
Tue 9/84:45 pm
PHL
-
STL
1 stop17h 55m
Frontier
Deal found 7/22$106
This Kiwi.com deal was found by Cheapflights users on 7/22. 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.
Mon 8/174:57 pm
STL
-
PHL
1 stop13h 18m
Frontier
Sat 8/224:45 pm
PHL
-
STL
1 stop25h 37m
Frontier
Deal found 7/22$112
This Kiwi.com deal was found by Cheapflights users on 7/22. 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.
Mon 10/510:35 am
STL
-
PHL
1 stop20h 01m
Frontier
Fri 10/95:38 pm
PHL
-
STL
1 stop17h 02m
Frontier
Deal found 7/22$113
This Kiwi.com deal was found by Cheapflights users on 7/23. 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.
Fri 10/3010:35 am
STL
-
PHL
1 stop6h 40m
Frontier
Sat 10/315:28 pm
PHL
-
STL
1 stop18h 12m
Frontier
Deal found 7/23$116
This Kiwi.com deal was found by Cheapflights users on 7/22. 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.
Mon 8/246:17 pm
STL
-
PHL
1 stop11h 58m
Frontier
Fri 8/286:30 am
PHL
-
STL
1 stop11h 52m
Frontier
Deal found 7/22$117
This Kiwi.com deal was found by Cheapflights users on 7/22. 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.
Mon 8/316:17 pm
STL
-
PHL
1 stop11h 58m
Frontier
Thu 9/105:28 pm
PHL
-
STL
1 stop17h 12m
Frontier
Deal found 7/22$118
This Kiwi.com deal was found by Cheapflights users on 7/22. 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 10/810:35 am
STL
-
PHL
1 stop11h 46m
Frontier
Tue 10/139:10 am
PHL
-
STL
1 stop25h 30m
Frontier
Deal found 7/22$121
This Kiwi.com deal was found by Cheapflights users on 7/22. 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 8/206:17 pm
STL
-
PHL
1 stop11h 58m
Frontier
Mon 8/246:30 am
PHL
-
STL
1 stop11h 52m
Frontier
Deal found 7/22$122
This Kiwi.com deal was found by Cheapflights users on 7/22. 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 8/236:17 pm
STL
-
PHL
1 stop11h 58m
Frontier
Thu 8/276:30 am
PHL
-
STL
1 stop11h 52m
Frontier
Deal found 7/22$123
This Kiwi.com deal was found by Cheapflights users on 7/22. 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.
Fri 9/46:17 pm
STL
-
PHL
1 stop11h 58m
Frontier
Sat 9/54:45 pm
PHL
-
STL
1 stop25h 37m
Frontier
Deal found 7/22$125
This Kiwi.com deal was found by Cheapflights users on 7/22. 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.
Fri 9/46:17 pm
STL
-
PHL
1 stop11h 58m
Frontier
Wed 9/95:28 pm
PHL
-
STL
1 stop17h 12m
Frontier
Deal found 7/22$126
This Kiwi.com deal was found by Cheapflights users on 7/22. 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.
Fri 9/46:17 pm
STL
-
PHL
1 stop11h 58m
Frontier
Thu 9/105:28 pm
PHL
-
STL
1 stop17h 12m
Frontier
Deal found 7/22$132

Find 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 July 23, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$106
(Kiwi.com)

One-way from

$50
(Trip.com)

Popular in

November

Cheapest in

August

Average price

$489

Good round-trip deal

$366 or less

Good one-way deal

$268 or less
Provider with most accurate pricing for Lambert-St Louis-Philadelphia flight deals.
Search Deals
Provider most trusted by Cheapflights users for Lambert-St Louis-Philadelphia flights.
Search Deals
From Lambert-St Louis to Philadelphia
Search Deals
One-way flight from Lambert-St Louis to Philadelphia
Search Deals
Highest demand for flights based on searches. 6% potential increase in price ($30 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 1% potential price decrease ($8 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in July 2026
Search Deals
Price to beat on a round-trip flight from Lambert-St Louis to Philadelphia.
Search Deals
Price to beat on a one-way flight from Lambert-St Louis to Philadelphia.
Search Deals

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 July 23, 2026.
Use the filters below to find and compare flights from St. Louis to Philadelphia that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Thu 8/20

6:05 am-12:25 pm

1 stop5h 20m

Philadelphia

Thu 8/27

6:20 am-7:35 am

Nonstop2h 15m

$287
Quickest round-trip

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Sat 9/5

10:15 am-1:25 pm

Nonstop2h 10m

Philadelphia

Mon 9/7

6:20 am-7:35 am

Nonstop2h 15m

$301

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Mon 8/24

10:05 am-5:55 pm

2 stops6h 50m

Philadelphia

Tue 8/25

3:05 pm-10:10 pm

2 stops8h 05m

$307

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Thu 10/15

1:05 pm-9:50 pm

2 stops7h 45m

Philadelphia

Mon 10/19

6:55 am-4:10 pm

2 stops10h 15m

$331

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Fri 10/9

7:50 pm-11:10 pm

Nonstop2h 20m

Philadelphia

Mon 10/12

6:25 am-7:45 am

Nonstop2h 20m

$370

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Mon 10/5

10:40 am-1:55 pm

Nonstop2h 15m

Philadelphia

Fri 10/9

6:25 am-7:45 am

Nonstop2h 20m

$375

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Fri 10/2

11:40 am-6:30 pm

1 stop5h 50m

Philadelphia

Mon 10/5

6:25 am-7:45 am

Nonstop2h 20m

$385

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Sun 10/4

5:45 am-1:10 pm

2 stops6h 25m

Philadelphia

Wed 10/7

7:45 am-3:00 pm

2 stops8h 15m

$413

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Fri 12/4

7:40 am-4:35 pm

2 stops7h 55m

Philadelphia

Mon 12/7

1:25 pm-5:10 pm

1 stop4h 45m

$419

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Sun 9/27

6:00 am-1:15 pm

1 stop6h 15m

Philadelphia

Wed 9/30

5:20 am-9:00 am

1 stop4h 40m

$422

Flights are sorted by cheapest round-trip flights first.

Deals found on 7/18

Showing 1-10 of 24 resultsSorted by cheapest first
1
2
3

Compare providers for flights from St. Louis to Philadelphia

Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.
Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from St. Louis to Philadelphia in July.
ProviderPrice AccuracyTrust Score*
ExpediaPrice Accuracy1 starTrust Score*3 stars
FlightHubPrice Accuracy3 starsTrust Score*3 stars
eDreamsPrice Accuracy2 starsTrust Score*3 stars
JustAirTicketPrice Accuracy-Trust Score*1 star
CheapflightsfaresPrice Accuracy2 starsTrust Score*1 star

*The Trust Score is based on feedback from users after their booking experience. It measures overall satisfaction, helping us identify issues like hidden fees, problems during the ticketing process, and the quality of customer service. This score is our best indicator of the provider's quality and reliability.

  • Most accurate provider: When it comes to deals on St. Louis-Philadelphia flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on St. Louis-Philadelphia flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from St. Louis-Philadelphia flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on St. Louis-Philadelphia flights, Cheapflights users trust FlightHub the most. FlightHub has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for St. Louis-Philadelphia flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.

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?

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 90 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 $322). Flying from St. Louis to Philadelphia in November is currently the most expensive (average of $509). 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 July 23, 2026.

It’s typically best to fly out from St. Louis to Philadelphia in the evening. Doing so could potentially save you 52% 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 July 18, 2026.

Travelers seeking maximum savings on their St. Louis to Philadelphia flight should consider departing on Monday 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.

How much does it cost to fly round-trip from St. Louis to Philadelphia?

Airfare is below average for this route at the moment.

St. Louis to Philadelphia flights typically cost between $301 and $488 in August.
The cheapest round-trip price found within the last 5 days was $106 on Frontier (Aug 31-Sep 8).

The best insider tips for St. Louis to Philadelphia flights

AI-powered summary based on content written by travel experts. AI can make mistakes.
Cheapflights partnered with top experts to bring you the best recommendations for your St. Louis to Philadelphia trip
Our travel experts
Mark Chesnut

Mark Chesnut

Expert on PHL

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 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

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 July 23, 2026.
Read reviews from past customers who have flown Southwest,American Airlines, andFrontier 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
4,238 reviews

Food

7.0

Overall

8.0

Boarding

8.1

Comfort

8.0

Entertainment

7.5

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Libby,Jun 2026

TUS - LAS

One delay in a 2 layover flight=a good trip. The crew was great.
Southwest
8.0
Very good
4,238 reviews
Southwest
8.0
Very good
4,238 reviews

Food

7.0

Overall

8.0

Boarding

8.1

Comfort

8.0

Entertainment

7.5

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Libby,Jun 2026

TUS - LAS

One delay in a 2 layover flight=a good trip. The crew was great.
American Airlines
7.1
Good
11,834 reviews
Southwest
8.0
Very good
4,238 reviews

Food

7.0

Overall

8.0

Boarding

8.1

Comfort

8.0

Entertainment

7.5

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Libby,Jun 2026

TUS - LAS

One delay in a 2 layover flight=a good trip. The crew was great.
Frontier
5.6
Fair
2,770 reviews
Southwest
8.0
Very good
4,238 reviews

Food

7.0

Overall

8.0

Boarding

8.1

Comfort

8.0

Entertainment

7.5

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Libby,Jun 2026

TUS - LAS

One delay in a 2 layover flight=a good trip. The crew was great.

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 7 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 3 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, 19 users have taken a look at flights from Lambert-St Louis to Philadelphia.

  • How long is the flight from St. Louis to Philadelphia?

    There are many flights that can get you from St. Louis to Philadelphia in 5h 20m. Fly via Southwest to get the fastest option. Airlines will cover a distance of 811 mi.

  • 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 $142. Other airlines that can offer you cheap pricing are American Airlines, from $275, and Southwest, from $277. These flights start at 66% lower than the current average price 3 months from now.

  • What are the cheapest airlines to fly from St. Louis to Philadelphia one-way?

    For one-way options, check prices for Frontier. According to our data, you can fly for as low as $72. Users have also found prices from $138 and $144 on American Airlines and Southwest, respectively.

  • 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 Iberia (89%), Aer Lingus (87%) or British Airways (85%) 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 $789, our data shows the cheapest flight currently is $139. When looking at the most popular route, (Lambert-St Louis - Philadelphia), you can expect to pay $269 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 $322). Flying from St. Louis to Philadelphia in November is currently the most expensive (average of $509). 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
Wildwood
King of Prussia
Reading
Camden
Ocean City
Cherry Hill
Lewes
Plymouth Meeting
Wyomissing
Wildwood Crest
Pottstown
Ephrata
Milford
Dover
Elkton
Essington
Willow Grove
New Castle
Millville
Vineland

Browse thousands of different options on Cheapflights for your next trip

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Top 3 airlines flying from St. Louis to Philadelphia

Discover the top 3 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 July 23, 2026.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$142Average$239FlexibilityNo cancel feeOn-time62%
American AirlinesCheapest$275Average$446FlexibilityNo cancel feeOn-time71%
SouthwestCheapest$277Average$463FlexibilityNo cancel feeOn-time63%

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