$94 Cheap Flights from Philadelphia (PHL) to St. Louis (STL)

View $94 flight on Sat, Apr 26, 2025Opens in a new window

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Find available prices by choosing your travel dates.

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

Prices were available within the past 7 days and start at $94 for one-way flights and $188 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Frontier Airlines
Tue, May 6 - Wed, May 7
TTN
Trenton
STL
St. Louis
$188 Roundtrip, found 13 hours ago
$188
Roundtrip
found 13 hours ago
Select Frontier Airlines flight, departing Tue, May 6 from Trenton to St. Louis, returning Wed, May 7, priced at $188 found 13 hours ago
Frontier Airlines
Sat, May 10 - Sat, May 17
PHL
Philadelphia
STL
St. Louis
$188 Roundtrip, found 2 hours ago
$188
Roundtrip
found 2 hours ago
Select Frontier Airlines flight, departing Sat, May 10 from Philadelphia to St. Louis, returning Sat, May 17, priced at $188 found 2 hours ago
Frontier Airlines
Mon, May 5 - Wed, May 7
TTN
Trenton
STL
St. Louis
$198 Roundtrip, found 13 hours ago
$198
Roundtrip
found 13 hours ago
Select Frontier Airlines flight, departing Mon, May 5 from Trenton to St. Louis, returning Wed, May 7, priced at $198 found 13 hours ago
Frontier Airlines
Tue, May 13 - Thu, May 15
PHL
Philadelphia
STL
St. Louis
$205 Roundtrip, found 13 hours ago
$205
Roundtrip
found 13 hours ago
Select Frontier Airlines flight, departing Tue, May 13 from Philadelphia to St. Louis, returning Thu, May 15, priced at $205 found 13 hours ago
Frontier Airlines
Tue, Jun 3 - Sat, Jun 7
PHL
Philadelphia
STL
St. Louis
$208 Roundtrip, found 1 hour ago
$208
Roundtrip
found 1 hour ago
Select Frontier Airlines flight, departing Tue, Jun 3 from Philadelphia to St. Louis, returning Sat, Jun 7, priced at $208 found 1 hour ago
Spirit Airlines
Tue, May 6 - Thu, May 15
PHL
Philadelphia
STL
St. Louis
$212 Roundtrip, found 1 day ago
$212
Roundtrip
found 1 day ago
Select Spirit Airlines flight, departing Tue, May 6 from Philadelphia to St. Louis, returning Thu, May 15, priced at $212 found 1 day ago
Frontier Airlines
Mon, Jun 2 - Sat, Jun 7
PHL
Philadelphia
STL
St. Louis
$214 Roundtrip, found 4 days ago
$214
Roundtrip
found 4 days ago
Select Frontier Airlines flight, departing Mon, Jun 2 from Philadelphia to St. Louis, returning Sat, Jun 7, priced at $214 found 4 days ago
American Airlines
Wed, Jun 4 - Tue, Jun 10
PHL
Philadelphia
STL
St. Louis
$301 Roundtrip, found 3 hours ago
$301
Roundtrip
found 3 hours ago
Select American Airlines flight, departing Wed, Jun 4 from Philadelphia to St. Louis, returning Tue, Jun 10, priced at $301 found 3 hours ago
Southwest Airlines
Wed, Jun 4 - Tue, Jun 10
PHL
Philadelphia
STL
St. Louis
$301 Roundtrip, found 3 hours ago
$301
Roundtrip
found 3 hours ago
Select Southwest Airlines flight, departing Wed, Jun 4 from Philadelphia to St. Louis, returning Tue, Jun 10, priced at $301 found 3 hours ago
United
Wed, Jun 4 - Tue, Jun 10
PHL
Philadelphia
STL
St. Louis
$321 Roundtrip, found 3 hours ago
$321
Roundtrip
found 3 hours ago
Select United flight, departing Wed, Jun 4 from Philadelphia to St. Louis, returning Tue, Jun 10, priced at $321 found 3 hours ago
Flights from Trenton (TTN) to St. Louis (STL)
Origin airport
Mercer
Destination airport
Lambert-St. Louis Intl.
Airlines serving
Alaska Airlines, American Airlines, Delta, Frontier Airlines, Southwest Airlines, Spirit Airlines, United
Roundtrip price
$188
Distance
834 mi

Philadelphia to St. Louis Flights

The cheapest times to fly from Philadelphia to St. Louis

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 Philadelphia to St. Louis are during the month of May. You can find some of the cheapest flights from Philadelphia to St. Louis with Expedia's search tool and vast selection of airlines.

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

Sunday is one of the best days to book for cheap flights from Philadelphia to St. Louis: 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 Philadelphia to St. Louis

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 Philadelphia to St. Louis in 2025. You can also book with separate airlines for your outbound and return journeys, from $94 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 Philadelphia to St. Louis 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 Philadelphia to St. Louis 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 Philadelphia Intl. Airport (PHL) to Lambert-St. Louis Intl. Airport (STL) cost?
You can book cheap return flights starting from $301 from Philadelphia Intl. Airport (PHL) to Lambert-St. Louis Intl. Airport (STL). 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 Southwest Airlines flight leaving PHL on May 20 2025 and touching down at STL. The price was last updated on April 23 2025 and has not changed since.
What is the cheapest month to fly from PHL to STL?
The cheapest flights from PHL to STL 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 Philadelphia Intl. Airport (PHL) to Lambert-St. Louis Intl. Airport (STL)?
Take a direct flight with American Airlines and head straight from Philadelphia Intl. Airport (PHL) to Lambert-St. Louis Intl. Airport (STL).
What is the cheapest airline that flies from PHL to STL?
With tickets starting at $151 for a one-way journey from PHL to STL, Southwest Airlines is currently the cheapest airline operating this route. This fare is based on the lowest price found on Expedia departing within the next three months. The flight takes off from PHL on June 11 2025. Prices were last updated on April 23 2025 and have not changed since.
How many flights per day from Philadelphia Intl. Airport (PHL) to Lambert-St. Louis Intl. Airport (STL)?
With, on average, 2 direct flights departing from Philadelphia Intl. Airport (PHL) to Lambert-St. Louis Intl. Airport (STL) each day, you’ll be on your way in no time.
What are the most popular departure times for flights from Philadelphia Intl. Airport (PHL) to Lambert-St. Louis Intl. Airport (STL)?
More travelers fly between PHL and STL at 11 AM than at any other time of day. Looking to skip the crowds? Pick a flight outside the busiest times and you’re likely to save on your fare as well.
What day of the week has the most flights from PHL to STL?
Depart on a Friday if you’re searching for the largest selection of flights from Philadelphia Intl. Airport (PHL) to Lambert-St. Louis Intl. Airport (STL).
What is the earliest flight from Philadelphia Intl. Airport (PHL) to Lambert-St. Louis Intl. Airport (STL)?
The first flight of the day leaving Philadelphia Intl. Airport (PHL) is at around 7:20AM UTC-5. Board this plane and you’ll reach Lambert-St. Louis Intl. Airport (STL) at approximately 9:05AM UTC-6. The total travel time is 2h 45m.
How long does it take to fly from Philadelphia Intl. Airport (PHL) to Lambert-St. Louis Intl. Airport (STL)?
It takes about 2 hours and 41 minutes to travel the 810 mi from PHL to STL.
What airline has the least delays from PHL to STL?
Consider traveling with American Airlines if you’d like to go straight from Philadelphia Intl. Airport (PHL) to Lambert-St. Louis Intl. Airport (STL) without any delays. This carrier has the strongest track record for punctuality, with an on-time performance of 82%. Want to get notified of any changes? You can keep an eye on your flight status using the Expedia App.
What is the best time to fly from Philadelphia Intl. Airport (PHL) to Lambert-St. Louis Intl. Airport (STL)?
To arrive at Lambert-St. Louis Intl. Airport (STL) on time, select a flight that leaves from Philadelphia Intl. Airport (PHL) before 3 PM. The chance of cancellations is 22% higher, on average, for departures after this hour.**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 St. Louis from Philadelphia Intl. Airport (PHL)?
If you’re boarding a direct flight from Philadelphia Intl. Airport (PHL) to St. Louis, Lambert-St. Louis Intl. Airport (STL) is the only airport you can touch down at.
Is it cheaper to buy a plane ticket from Philadelphia Intl. Airport (PHL) to Lambert-St. Louis Intl. Airport (STL) last-minute?
Last-minute fares from PHL to STL are generally more expensive. To secure the best prices, start searching for flights early. That being said, if you can play around with your travel dates, you may score a cheap ticket right before your journey.
Is it cheaper to book a PHL to STL flight and hotel package?
Booking a PHL to STL flight and hotel package tends to be cheaper than booking separately. With Expedia, you can enjoy the convenience of organizing your trip all in one place. Choose from our extensive range of hotels and then add flights, car rentals and activities to your booking. Bundle it all together, and you could save hundreds of dollars.
Can I cancel or change the date of my flight from Philadelphia Intl. Airport (PHL) to Lambert-St. Louis Intl. Airport (STL)?
If you booked your PHL to STL flight in the last 24 hours, you may be able to modify or cancel it without any fees. Depending on the airline and the ticket type you purchased, additional charges may apply for changes beyond that time. Airline policies and contact information can be found in your itinerary or confirmation email. Or, head to our Customer Service portal for more information.

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