$74 Cheap Flights from St. Louis (STL) to Philadelphia (PHL)

View $74 flight on Fri, Aug 8, 2025Opens in a new window

Popular airlines from St. Louis Lambert Intl. Airport (STL) to Philadelphia Intl. Airport (PHL)

Cheap Flights from St. Louis to Philadelphia (STL-PHL)

Prices were available within the past 7 days and start at $74 for one-way flights and $113 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Southwest Airlines
Tue, Aug 12 - Thu, Aug 14
STL
St. Louis
PHL
Philadelphia
$113 Roundtrip, found 2 days ago
$113
Roundtrip
found 2 days ago
Select Southwest Airlines flight, departing Tue, Aug 12 from St. Louis to Philadelphia, returning Thu, Aug 14, priced at $113 found 2 days ago
Spirit Airlines
Thu, Aug 21 - Mon, Aug 25
STL
St. Louis
PHL
Philadelphia
$115 Roundtrip, found 4 days ago
$115
Roundtrip
found 4 days ago
Select Spirit Airlines flight, departing Thu, Aug 21 from St. Louis to Philadelphia, returning Mon, Aug 25, priced at $115 found 4 days ago
Southwest Airlines
Tue, Aug 12 - Thu, Aug 14
STL
St. Louis
PHL
Philadelphia
$123 Roundtrip, found 2 days ago
$123
Roundtrip
found 2 days ago
Select Southwest Airlines flight, departing Tue, Aug 12 from St. Louis to Philadelphia, returning Thu, Aug 14, priced at $123 found 2 days ago
Spirit Airlines
Thu, Sep 4 - Tue, Sep 9
STL
St. Louis
PHL
Philadelphia
$131 Roundtrip, found 3 days ago
$131
Roundtrip
found 3 days ago
Select Spirit Airlines flight, departing Thu, Sep 4 from St. Louis to Philadelphia, returning Tue, Sep 9, priced at $131 found 3 days ago
Southwest Airlines
Tue, Sep 9 - Sat, Sep 13
STL
St. Louis
PHL
Philadelphia
$132 Roundtrip, found 2 days ago
$132
Roundtrip
found 2 days ago
Select Southwest Airlines flight, departing Tue, Sep 9 from St. Louis to Philadelphia, returning Sat, Sep 13, priced at $132 found 2 days ago
Spirit Airlines
Sat, Aug 2 - Thu, Aug 14
STL
St. Louis
PHL
Philadelphia
$138 Roundtrip, found 3 days ago
$138
Roundtrip
found 3 days ago
Select Spirit Airlines flight, departing Sat, Aug 2 from St. Louis to Philadelphia, returning Thu, Aug 14, priced at $138 found 3 days ago
Southwest Airlines
Sat, Oct 18 - Tue, Oct 21
STL
St. Louis
PHL
Philadelphia
$146 Roundtrip, found 4 days ago
$146
Roundtrip
found 4 days ago
Select Southwest Airlines flight, departing Sat, Oct 18 from St. Louis to Philadelphia, returning Tue, Oct 21, priced at $146 found 4 days ago
American Airlines
Tue, Aug 12 - Thu, Aug 14
STL
St. Louis
PHL
Philadelphia
$147 Roundtrip, found 2 days ago
$147
Roundtrip
found 2 days ago
Select American Airlines flight, departing Tue, Aug 12 from St. Louis to Philadelphia, returning Thu, Aug 14, priced at $147 found 2 days ago
Delta
Tue, Aug 12 - Thu, Aug 14
STL
St. Louis
PHL
Philadelphia
$217 Roundtrip, found 2 days ago
$217
Roundtrip
found 2 days ago
Select Delta flight, departing Tue, Aug 12 from St. Louis to Philadelphia, returning Thu, Aug 14, priced at $217 found 2 days ago
United
Sat, Sep 20 - Thu, Sep 25
STL
St. Louis
PHL
Philadelphia
$237 Roundtrip, found 5 hours ago
$237
Roundtrip
found 5 hours ago
Select United flight, departing Sat, Sep 20 from St. Louis to Philadelphia, returning Thu, Sep 25, priced at $237 found 5 hours ago

Find the cheapest month to fly from St. Louis (STL) to Philadelphia (PHL)

October is typically the cheapest month to fly

From $78 - $417 per traveler.

Graph displaying average flight prices per month

Alternative airports near Philadelphia

Prices were available within the past 7 days. Prices and availability are subject to change.

Select flight to New Castle ILG. Average driving time to city center is 44 minutes. Flights from $454
ILG
New Castle
Average driving time to city center44 min
Flights from $454
Flights from St. Louis (STL) to Philadelphia (PHL)
Origin airport
Lambert-St. Louis Intl.
Destination airport
Philadelphia Intl.
Airlines serving
American Airlines, Delta, Frontier Airlines, Southwest Airlines, Spirit Airlines, United
Roundtrip price
$113
Distance
811 mi
Average flight time
3 hours 13 mins

St. Louis to Philadelphia Flights

The cheapest times to fly from St. Louis to Philadelphia

On average, Thursday can be the cheapest time to fly, according to data from the Airlines Reporting Corporation (ARC), one of the world's biggest databases for global airline sales. The data reveals that you could save up to 16% by flying on a Thursday—the cheapest day to travel on average—instead of a Sunday—the most expensive. Some of the most affordable flights from St. Louis to Philadelphia are during the month of August. You can find some of the cheapest flights from St. Louis to Philadelphia with Expedia's search tool and vast selection of airlines.

 

The best time to book a flight from St. Louis to Philadelphia

Sunday is one of the best days to book for cheap flights from St. Louis to Philadelphia: Tickets reserved on a Sunday cost between 6% and 13% less than those reserved on a Friday, according to ARC data. The data also suggests booking early can also lead to cheaper airfares. You could save 24% by buying your tickets for domestic flights at least a month in advance and 10% by booking international flights 2 months in advance.

 

How to find cheap round-trip tickets from St. Louis to Philadelphia

Being flexible with your dates and using Expedia's Price Drop Protection and Price Tracking features are some of the best ways of finding a cheap ticket from St. Louis to Philadelphia in 2025. You can also book with separate airlines for your outbound and return journeys, from $74 one-way. Expedia also offers Price Drop Protection, so if the cost of your airfare goes down after booking, you'll receive a credit for the difference*. This is available for a small fee, and is free to One Key Gold and Platinum tier members.

 

Expedia's Price Tracking feature means you can stay on top of airfares without manually checking every day. It sends you automated price alerts for cheap St. Louis to Philadelphia flights and uses historical data to indicate when the best time to book is. Download Expedia's free app to activate this handy tool in a few easy taps.

 

You could also save big by booking one of Expedia's vacation packages. Bundling together your St. Louis to Philadelphia airfare with your accommodations and car rental is often cheaper than booking everything separately. There’s also One Key, Expedia's generous rewards program. Join for free and you could earn One Key cash on most bookings to save on future adventures.

 

*Terms apply.

 

Disclaimer: ARC The statistics are based on average round-trip ticket prices between January and August 2023. The percentages you see are averages.

 

Frequently asked questions

How much does a flight from Lambert-St. Louis Intl. Airport (STL) to Philadelphia Intl. Airport (PHL) cost?
Cheap round-trip fares from Lambert-St. Louis Intl. Airport (STL) to Philadelphia Intl. Airport (PHL) start at $113. This information is based on the cheapest price found on Expedia for this return journey departing within the next three months. This airfare is for a American Airlines flight leaving STL on August 6 2025 and touching down at PHL. The price was last updated on July 10 2025 and has not changed since.
What is the cheapest month to fly from STL to PHL?
The cheapest flights from STL to PHL are usually during off-peak season, when demand is lower. To save money, avoid flying during public holidays, school breaks and major local events.
Which airlines fly direct from Lambert-St. Louis Intl. Airport (STL) to Philadelphia Intl. Airport (PHL)?
When heading out of Lambert-St. Louis Intl. Airport (STL), you can take a nonstop flight to Philadelphia Intl. Airport (PHL) with American Airlines.
What is the cheapest airline that flies from STL to PHL?
Book a flight from STL to PHL with American Airlines. This airline currently has the cheapest one-way ticket for this route, starting at $57. This fare is based on the lowest price found on Expedia departing within the next three months. The flight takes off from STL on September 4 2025. Prices were last updated on July 10 2025 and have not changed since.
How many flights per day from Lambert-St. Louis Intl. Airport (STL) to Philadelphia Intl. Airport (PHL)?
With, on average, 2 nonstop flights departing from Lambert-St. Louis Intl. Airport (STL) to Philadelphia Intl. Airport (PHL) each day, you'll be taking off on vacation soon enough.
What are the most popular departure times for flights from Lambert-St. Louis Intl. Airport (STL) to Philadelphia Intl. Airport (PHL)?
More travelers fly between STL and PHL at 6 AM than at any other point in the day. Rather skip the crowds? Try choosing a quieter departure window and it's possible you'll save on your fare as well.
What day of the week has the most flights from STL to PHL?
If you jet off on a Friday, you'll get the largest range of choices for flights from Lambert-St. Louis Intl. Airport (STL) to Philadelphia Intl. Airport (PHL).
What is the earliest flight from Lambert-St. Louis Intl. Airport (STL) to Philadelphia Intl. Airport (PHL)?
Lambert-St. Louis Intl. Airport (STL)'s first flight to Philadelphia Intl. Airport (PHL) departs at approximately 6:00AM UTC-6. With a travel time of 2h 10m, you'll arrive at around 9:10AM UTC-5.
How long does it take to fly from Lambert-St. Louis Intl. Airport (STL) to Philadelphia Intl. Airport (PHL)?
Flights from STL to PHL have an average travel time of 2 hours and 9 minutes. The total distance between these two airports is 810 mi.
What airline has the least delays from STL to PHL?
With 82% of flights usually arriving as scheduled, American Airlines has the best on-time performance for nonstop flights from Lambert-St. Louis Intl. Airport (STL) to Philadelphia Intl. Airport (PHL). To check your flight status and get notified about any changes, use the Expedia App.
What is the best time to fly from Lambert-St. Louis Intl. Airport (STL) to Philadelphia Intl. Airport (PHL)?
Opt for a flight from Lambert-St. Louis Intl. Airport (STL) to Philadelphia Intl. Airport (PHL) that takes off before 3 PM to reduce the risk of cancellations. Departures after this time have a 22% higher chance of being canceled, on average.**Most reliable time of the day and month to travel recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.
What airports do you fly into for Philadelphia from Lambert-St. Louis Intl. Airport (STL)?
If you're taking a direct flight from Lambert-St. Louis Intl. Airport (STL) to Philadelphia, Philadelphia Intl. Airport (PHL) is the only airport you can touch down at.
Is it cheaper to buy a plane ticket from Lambert-St. Louis Intl. Airport (STL) to Philadelphia Intl. Airport (PHL) last-minute?
Holding off until just before your departure to book a ticket from STL to PHL generally means paying more. Although you may find some last-minute discounts, there's no guarantee. Keep your travel plans flexible to maximize your chances of snagging a bargain.
Is it cheaper to book a STL to PHL flight and hotel package?
You'll generally save money by securing a STL to PHL flight and hotel package compared to booking separately. In fact, you could save hundreds of dollars by bundling with Expedia. And it's easy to manage it all in one place. Once you've chosen your ideal flights and accommodations, consider adding extras including tours, activities and car rentals.
Can I cancel or change the date of my flight from Lambert-St. Louis Intl. Airport (STL) to Philadelphia Intl. Airport (PHL)?
In most cases, you can modify or cancel your STL to PHL flight. However, there may be additional fees, especially if your booking was made more than 24 hours ago. Double-check your itinerary for the airline's fees and policies on flight changes, or if you'd like further details, visit our Customer Service portal.

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*Available to One Key members.