STL - PHL

$50 Find Cheap Flights from St. Louis to Philadelphia - Compare and Save

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from St. Louis to Philadelphia departing on 9/22. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy, 0 bags

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Everything you should know

Cheapest round-trip
$106
Typical prices: $229-$453
Frontier
Mon 8/31Tue 9/8
STL - PHL • 1 stop
Cheapest non-stop
$277
Typical prices: $309-$463
American Airlines
Tue 9/22Mon 9/28
STL - PHL • Non-stop
Advice from real travelers
AI-powered summary based on content written by travel experts. AI can make mistakes.
Qatar Airways economy adds a free checked bag; British Airways includes a carry-on.
American Main Cabin Extra adds early boarding; Southwest offers Cash + Points.
Expert advice
Expert advice
Expert advice
Expert advice
Nonstop flights
You can fly direct with American Airlines and Southwest. Average duration is 2h 15m
Direct flights
Direct flights
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Direct flights
Direct flights
+1
Top layover airports
Cheapest • Avg $221 (round-trip)
Shortest trip • 4h 19m (one-way)
Insights
Insights
Insights
Insights
When to book
in advance
Our data shows that travelers who book at least 4 weeks in advance save around 27% compared to booking last minute.
Insights
Insights
Insights
Insights
When to travel
Cheapest • 22% price drop
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
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We hope you love your trip to Philadelphia!
Flight Deals
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Flight Deals

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

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from St. Louis to Philadelphia that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from St. Louis to Philadelphia

Mon, Aug 31 - Tue, Sep 8
Frontier Logo
6:17 pm - 7:15 am
STL
-
PHL
11h 58m
1 stop
Frontier Logo
4:45 pm - 9:40 am
PHL
-
STL
17h 55m
1 stop
$106Frontier
Mon, Aug 17 - Sat, Aug 22
Frontier Logo
4:57 pm - 7:15 am
STL
-
PHL
13h 18m
1 stop
Frontier Logo
4:45 pm - 5:22 pm
PHL
-
STL
25h 37m
1 stop
$112Frontier
Mon, Oct 5 - Fri, Oct 9
Frontier Logo
10:35 am - 7:36 am
STL
-
PHL
20h 01m
1 stop
Frontier Logo
5:38 pm - 9:40 am
PHL
-
STL
17h 02m
1 stop
$113Frontier
Mon, Aug 24 - Fri, Aug 28
Frontier Logo
6:17 pm - 7:15 am
STL
-
PHL
11h 58m
1 stop
Frontier Logo
6:30 am - 5:22 pm
PHL
-
STL
11h 52m
1 stop
$117Frontier
Mon, Aug 31 - Thu, Sep 10
Frontier Logo
6:17 pm - 7:15 am
STL
-
PHL
11h 58m
1 stop
Frontier Logo
5:28 pm - 9:40 am
PHL
-
STL
17h 12m
1 stop
$118Frontier
Thu, Oct 8 - Tue, Oct 13
Frontier Logo
10:35 am - 11:21 pm
STL
-
PHL
11h 46m
1 stop
Frontier Logo
9:10 am - 9:40 am
PHL
-
STL
25h 30m
1 stop
$121Frontier
Thu, Aug 20 - Mon, Aug 24
Frontier Logo
6:17 pm - 7:15 am
STL
-
PHL
11h 58m
1 stop
Frontier Logo
6:30 am - 5:22 pm
PHL
-
STL
11h 52m
1 stop
$122Frontier
Sun, Aug 23 - Thu, Aug 27
Frontier Logo
6:17 pm - 7:15 am
STL
-
PHL
11h 58m
1 stop
Frontier Logo
6:30 am - 5:22 pm
PHL
-
STL
11h 52m
1 stop
$123Frontier
Fri, Sep 4 - Sat, Sep 5
Frontier Logo
6:17 pm - 7:15 am
STL
-
PHL
11h 58m
1 stop
Frontier Logo
4:45 pm - 5:22 pm
PHL
-
STL
25h 37m
1 stop
$125Frontier
Fri, Sep 4 - Wed, Sep 9
Frontier Logo
6:17 pm - 7:15 am
STL
-
PHL
11h 58m
1 stop
Frontier Logo
5:28 pm - 9:40 am
PHL
-
STL
17h 12m
1 stop
$126Frontier
Booking Insights

KAYAK's insights & trends for St. Louis to Philadelphia flights

Get data-powered insights and trends into flights from St. Louis to Philadelphia to help you find the cheapest flights, the best time to fly and much more.

How much is a round-trip flight from St. Louis to Philadelphia?

This analysis is based on the cheapest round-trip price found on KAYAK in the last 12 months by searching for a flight from St. Louis to Philadelphia departing in August.

Flight prices are below average for this route right now.

Flights to Philadelphia from St. Louis usually cost between $221 and $443 in August.
The lowest price found in the past 5 days was $106 on Frontier (Aug 31-Sep 8).

What’s the cheapest day of the week to fly from St. Louis to Philadelphia?

The average price of all round-trip flights from St. Louis to Philadelphia clicked on KAYAK for each day over the last 12 months.

For St. Louis to Philadelphia, Friday is the cheapest day to fly on average and Saturday is the most expensive. Flying from Philadelphia back to St. Louis, the best deals are generally found on Wednesday, with Sunday being the most expensive.

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

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from St. Louis to Philadelphia, removes the top 0.1% to account for outliers, and then takes the median of all values for each month.

The cheapest month for flights from St. Louis to Philadelphia is September, where tickets cost $337 (return) on average. On the other hand, the most expensive months are November and July, where the average cost of round-trip tickets is $509 and $489 respectively.

Can I save money by flying with a layover from St. Louis to Philadelphia?

The average round-trip price for all non-stop flights, flights with one layover, and flights with two layovers for the route found by users searching on KAYAK in the last 2 weeks.

Yes, flying with a layover may cost you more time, but you can also save money on the route, with a 1 stop layover the cheapest option at $413 on average.

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

To calculate weekly average prices, KAYAK takes all prices for each week before departure over the last year for round-trip flights from St. Louis to Philadelphia, removes the top 0.1% to account for outliers, and then takes the average of all the values for each week.

To get a below average price on the flight from St. Louis to Philadelphia, you should book around 4 weeks before departure, which saves you about 27% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 15 weeks before departure.

Expert advice

Expert advice for your flight from St. Louis to Philadelphia

 
AI-powered summary based on content written by travel experts. AI can make mistakes.
KAYAK teamed up with top travel experts to share the best tips for your journey.
Our travel experts
Stefanie Waldek

Stefanie Waldek

Expert on Qatar Airways

Stefanie Waldek is a freelance space, travel, and design writer based in Saratoga Springs, NY. Her words have appeared in Space.com, Travel + Leisure, Condé Nast Traveler, Architectural Digest, and House Beautiful, among other publications. An expert in aviation and expedition cruising, Stefanie is frequently up in the air or on the sea, likely en route to Antarctica or the Arctic.

Duncan Madden

Duncan Madden

Expert on British Airways

Duncan is a freelance travel writer, copywriter and book author in constant search of travel stories and the perpetual sensation of being on holiday. He’s never happier than when on a dusty trail in search of empty waves or ducking under the piste tape in search of snowbound solitude. British born, living in Germany, but happiest heading for the horizon. His first book, Found in Translation, explores the etymologies and stories of country names around the world and is out now.

Harriet Baskas

Harriet Baskas

Expert on American Airlines and PHL

Harriet is an award-winning journalist who is happiest in an airport or an unusual museum. Her stories about airports, air travel, and the business of travel have appeared on NBC News, CNBC, USA TODAY, The Points Guy and other outlets. She is the creator of the StuckatTheAirport.com blog and the author of nine books. When not out on the road or exploring the latest airport amenities, she’s home in Seattle getting ready for the next adventure.

Blane Bachelor

Blane Bachelor

Expert on Southwest

Blane Bachelor is a journalist and editor specializing in travel and aviation who writes regularly for top global outlets. Born and raised in Florida, Blane has worked and lived in four countries, including the Netherlands, where she’s currently based with her family. Her favorite way to get to know a new destination is by running or riding a bike around town – or hearing a spooky ghost story about local history. She will always choose the window seat.

Yulia Denisyuk

Yulia Denisyuk

Expert on STL

Yulia is a freelance journalist who’s dispatched from 90+ countries. Her work focuses on cultures, adventure trips and air travel, appearing in NatGeo, NYT, CNTraveler, and more. For past assignments, she’s stayed with nomads in Mongolia and learned the art of Imigongo in Rwanda. She’s based in Chicago; in winter she often questions that decision.

Good to know

Low season

February

Cheapest flight

$50
Best time to beat the crowds with an average 1% drop in price.
Most popular time to fly with an average 14% increase in price.
Flight from St. Louis to Philadelphia

When to book flights from St. Louis to Philadelphia

Are your dates flexible? Find out the best times to travel from St. Louis to Philadelphia based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price
KAYAK looks at all historical flight data for each date to provide a predicted price for one-way trips or round-trips with a duration up to 40 days. While we try to provide actual minimum prices for each date, some prices are predictions and actual prices may differ.

FAQs for booking flights from St. Louis to Philadelphia

  • Does PHL have any pet relief areas?

    If you’re traveling with a pet through Philadelphia International Airport, please ensure that they remain in a safe carrier unless you’re using the pet relief areas. The pet relief areas at PHL are located at multiple points around the airport, including inside the terminals, in the departure areas, and the arrivals areas. For arriving passengers, the most conveniently-located relief areas can be found adjacent to Terminals A-East, Terminal B past baggage claim, and Terminal E along the Commercial Vehicle Roadway.

  • Which is the quickest way from St Louis to STL?

    There are multiple ways through which you can get to STL from the city center. The most popular method and also the most pocket-friendly would be using the metro, which can be boarded from the Civic Center. However, that isn’t the quickest. If you want to get to the airport within a shorter period, taking a taxi or driving via the I-64 W and I-170 N would be more ideal. This will take you about 15 minutes, while the metro will be 40 minutes on a good day.

  • Which airlines have a lounge at STL?

    At the moment, the only airline with a lounge at STL is American Airlines. They have an American Airlines Admirals Club located in Terminal 1 between Concourses B and C near Gate 1. Here you can find complimentary snacks and beverages, comfortable seats, TVs, and Wi-Fi. It is worth mentioning that the airport has other lounges: The USO Lounge and Wingtips Lounge, located in Concourse E on Terminal 2 near Gate E22.

  • How do I get to downtown Philadelphia from PHL?

    You can get to downtown Philly from PHL using multiple means, such as taxis, rental cars, airport shuttle, and public transit. For convenience, taxis and rental cars are a better choice since they are easily available at the airport and will take you to any destination in Philly. However, they are significantly more expensive compared to public transport.

  • What is the cheapest flight from St. Louis to Philadelphia?

    In the last 5 days, the lowest price for a flight from St. Louis to Philadelphia was $50 for a one-way ticket and $106 for a round-trip.

  • Do I need a passport to fly between St. Louis and Philadelphia?

    No

  • Which airports will I be using when flying from St. Louis to Philadelphia?

    When flying out of St. Louis you will be using Lambert-St Louis. You will be landing at Philadelphia, also known as Philadelphia.

  • Which airlines offer Wi-Fi service onboard planes from St. Louis to Philadelphia?

    American Airlines, JetBlue, Lufthansa, and Alaska Airlines offer inflight Wi-Fi service on the St. Louis to Philadelphia flight route.

  • Which aircraft models fly most regularly from St. Louis to Philadelphia?

    The Airbus A319 is the aircraft model that flies most regularly on the St. Louis to Philadelphia flight route.

  • Which airline alliances offer flights from St. Louis to Philadelphia?

    oneworld is the only airline alliance operating flights between St. Louis and Philadelphia.

  • On which days can I fly direct from St. Louis to Philadelphia?

    There are nonstop flights from St. Louis to Philadelphia on a daily basis.

  • Which is the best airline for flights from St. Louis to Philadelphia, Southwest or American Airlines?

    The two airlines most popular with KAYAK users for flights from St. Louis to Philadelphia are Southwest and American Airlines. With an average price for the route of $465 and an overall rating of 8.0, Southwest is the most popular choice. American Airlines is also a great choice for the route, with an average price of $448 and an overall rating of 7.1.

  • How does KAYAK find such low prices on flights from St. Louis to Philadelphia?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from St. Louis to Philadelphia.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from St. Louis to Philadelphia?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to Philadelphia from St. Louis is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from St. Louis to Philadelphia?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly to Philadelphia with an airline and back to St. Louis with another airline. Booking your flights between St. Louis and PHL can sometimes prove cheaper using this method.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from St. Louis to Philadelphia?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying to Philadelphia from St. Louis up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

KAYAK’s top tips for finding a cheap flight from St. Louis to Philadelphia

  • Looking for a cheap flight? 25% of our users found flights on this route for $278 or less one-way and $359 or less round-trip.
  • If you want to leave your car at St. Louis Lambert International Airport (STL), please ensure that you compare the rates charged by airport parking to those charged by offsite parking companies. In most cases, the offsite parking lots charge lower rates compared to airport parking, and you even get a free shuttle to the terminals.
  • Traveling moms will be happy to know that PHL has multiple nursing suites where you can privately breastfeed your child. The Mamava Suites are located in four different areas; in Terminals A West and Terminal F, as well as the B/C and D/E Connectors. These nursing suites are available for free to all travelers.
  • To save on flight costs, consider booking your flight tickets in advance and be flexible with your travel dates. For example, avoid traveling on holidays and weekends since the ticket demand is usually higher on such days, so airlines will charge higher prices for these tickets.
  • Consider booking direct flights instead of connecting flights to make your trip more sustainable. This is because direct flights are shorter and therefore end up burning less fuel leading to lower carbon emissions compared to connecting flights.
  • If you need specific in-flight services such as Wi-Fi, please confirm their availability during the booking. This is because different flights tend to offer varying services even when serviced by the same airline.

Prefer to fly direct from St. Louis to Philadelphia?

 
Direct data is based off flight results for the next 60 days. Find direct flights from all airlines flying direct from Lambert-St Louis to Philadelphia.
Find which airlines fly direct from Lambert-St Louis Airport to Philadelphia Airport, which days they fly and book direct flights.

Direct departures

Lambert-St Louis to Philadelphia

Monday

American Airlines,Southwest

American Airlines,Southwest

Tuesday

American Airlines,Southwest

American Airlines,Southwest

Wednesday

American Airlines,Southwest

American Airlines,Southwest

Thursday

American Airlines,Southwest

American Airlines,Southwest

Friday

American Airlines,Southwest

American Airlines,Southwest

Saturday

American Airlines,Southwest

American Airlines,Southwest

Sunday

American Airlines,Southwest

American Airlines,Southwest

See more direct flights

Direct returns

Philadelphia to Lambert-St Louis

Monday

American Airlines,Southwest

American Airlines,Southwest

Tuesday

American Airlines,Southwest

American Airlines,Southwest

Wednesday

American Airlines,Southwest

American Airlines,Southwest

Thursday

American Airlines,Southwest

American Airlines,Southwest

Friday

American Airlines,Southwest

American Airlines,Southwest

Saturday

American Airlines,Southwest

American Airlines,Southwest

Sunday

American Airlines,Southwest

American Airlines,Southwest

See more direct flights

Reviews of the top 3 airlines serving from St. Louis to Philadelphia

 
See real verified KAYAK customer reviews for airlines flying from St. Louis to Philadelphia. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from St. Louis to Philadelphia? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
8.0
SouthwestOverall score based on 4229 reviews
8.6Crew
8.0Comfort
7.0Food
8.1Boarding
7.5Entertainment
Airline reviews

Snacks are always pretzels. Why can't you also offer peanuts ?

6.0 GoodAnonymous, Mar 2026
STL - HOU
Read more Southwest reviews

Snacks are always pretzels. Why can't you also offer peanuts ?

Only downside was the legroom and seat width, which is always a problem unless I spend more for a premium seat.

Very good. Sad to learn Southwest is going start to charge for bags

Exceptional crew! Friendly and professional. Pleasant attitude and treated everyone with respect.

The flight was promptly on schedule and Southwest delivered everything they promised. No excuses for any shortfalls just 100% ownership of their responsibilities and business. The boarding and seating policy is a complete shambles. What started out as a great idea when Southwest first hit the market has been turned into a disaster due to the lack of integrity in many of the people who fly Southwest and take advantage of Southwest generosity at the expense of their fellow passengers.

Crew was excellent - Plane was fine. Media was good, could use more kid shows; Not a fan of the brownie brittle -- snack could be slightly better.

The crew was very nice and respectful and everything went well.

Left on time and arrived early. Brand new plane and no parts missing. Comfortable seats. The actual Captain spoke prior to the flight and reassured everyone about safety. Crew was so nice and fun. Perfect flight!

Everything went smoothly and the plane wasn’t full. It was delayed though. The delay was increased due to a crew change which was frustrating.

Love Southwest! Always a good trip with a happy crew who goes out of their way to be kind and fun.

the first flight smelled like urine Ac didn’t work pathetic experience

We were delayed due to a mechanical issue, but the gate staff and then later captain were giving thorough and frequent updates. Ended up being delayed about an hour, but we did get out, so it was overall a good flight!

My luggage never made it, I booked business class only to find out I’m sitting in the back. Very disappointed with the reservation

I found the seats ergonomically uncomfortable forcing the body to seat slightly hunched. For a short flight I worked on adjustments but for a longer flight, it would be difficult.

I cancelled this flight 2 days before departure but I followed your texts and emails and IF you were correct this flight turned into a nightmare.

The seats. The seat in front of me was awful and when the guy sat down, it flew back and hit my head when I was putting my backpack under the seat, It didn't make for a pleasant experience,

Cancelled flight. Still waiting to get home for grand daughter’s graduation .

Left early arrived early..right amount of talking from pilots..of course had to love the biscuit and water!

As we approached Denver, we encountered quite a bit of turbulence. I know this can sometimes be the case as I frequently fly this route but not on American. My gripe: Usually a pilot or co-pilot alerts passengers to the possibility of turbulance ahead of time. This did not occur nor did he communiucate during what was a pretty rough ride.

I very rarely fly American and my experience today reenforces that is the correct decision. While the staff were all very courteous, our flight was first thing in the morning so there was no reason to be delayed, yet appropriate maintenance checks weren’t completed prior to our flight so we were delayed multiple times. Not a great showing, American Airlines.

Not clean and was told I would get a great seat and it was not great at all

No knowledgeable staff at the counter or in a flight crew. No one knew why once flight landed at Philadelphia Airport then it took them 4 hours from runway to gate . Damn they took 4 hours to reach the gate . They messed up whole night for myself and for my kids.

Horrible communication about delay of flight and what options were available

Online check-in was not user-friendly. Too many fees, not cost effective.

FRONTIER SUCKS! The agent downstairs tricked me into booking, just to get to the gate. At the gate, they told me they couldn't help. I then called Customer Service. They and the gate attendants kept blaming each other. Neither side was willing to help the customer.

My experience with frontier staff at the Denver airport was absolutely horrible. The manager on duty was even worst if was the worst experience I have ever had, I have never been treated so poorly as a customer in my life! The staff was extremely rude, eye rolls and attitude and then refusal to help me at all. I wish I could never fly frontier again that’s how horrible it was!

Good for the price. My only complaint is that the pilot should keep the air flowing while passengers are waiting to getting out of airplane.

I arrived 1 hour prior to boarding, and they said I was too late for a domestic flight. First time I heard that :-(

Crew members are very rude and not cooperate with passengers.

Well, I didn’t have food! So NA wasn’t an option. I’ll be back!

Everything you need to know for your flight from St. Louis to Philadelphia

Information on your arrival and departure airports