STL - PHL

$90 Find Cheap Flights from St. Louis to Philadelphia

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 4/13. 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

KAYAK searches hundreds of travel sites at once for deals on flights to Philadelphia

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from St. Louis to Philadelphia, as well as popular online travel agencies
These are the airlines KAYAK users have selected most often from within our search results in flight searches from St. Louis to Philadelphia, as well as popular online travel agencies
Travelers love KAYAK
41,299,237 searches in the past 7 days on KAYAK

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Everything you should know

Cheapest round-trip
$180
Overall average: $407
Frontier
Wed 4/8Sat 4/11
STL - PHL • 1 stop
Cheapest non-stop
$277
Typical prices: $372-$485
Southwest
Wed 5/20Wed 5/27
STL - PHL • Non-stop
Advice from real travelers
AI-powered summary based on content written by travel experts. AI can make mistakes.
Main Cabin Extra on American offers early boarding.
Use SEPTA trains for a quick trip from PHL to downtown.
Expert advice
Expert advice
Expert advice
Expert advice
Top airlines
Cheapest • from $180 (round-trip)
Best reviews • 8.0 score
Airline reviews
Airline reviews
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Airline reviews
Airline reviews
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Nonstop flights
You can fly direct with American Airlines and Southwest. Average duration is 2h 13m
Direct flights
Direct flights
+1
+1
Direct flights
Direct flights
+1
Top layover airports
Cheapest • Avg $249 (round-trip)
Shortest trip • 4h 22m (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 28% compared to booking last minute.
Insights
Insights
Insights
Insights
When to travel
Cheapest • 32% price drop
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
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KAYAK searches 100s of sites at once to find you the best travel deals.
We hope you love your trip to Philadelphia!
Flight Deals
Booking Insights
Expert advice
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

Wed, Apr 8 - Sat, Apr 11
Frontier Logo
8:16 pm - 5:31 am
STL
-
PHL
8h 15m
1 stop
Frontier Logo
12:33 pm - 11:25 pm
PHL
-
STL
11h 52m
1 stop
$180Frontier
Wed, Apr 8 - Wed, Apr 15
Frontier Logo
8:16 pm - 5:31 am
STL
-
PHL
8h 15m
1 stop
Frontier Logo
8:41 pm - 7:21 pm
PHL
-
STL
23h 40m
1 stop
$191Frontier
Fri, May 1 - Fri, May 8
Frontier Logo
8:23 pm - 8:10 am
STL
-
PHL
10h 47m
1 stop
Frontier Logo
8:35 pm - 7:23 pm
PHL
-
STL
23h 48m
1 stop
$193Frontier
Thu, Apr 30 - Sat, May 2
Frontier Logo
11:21 am - 7:19 pm
STL
-
PHL
6h 58m
1 stop
Frontier Logo
4:42 pm - 11:19 pm
PHL
-
STL
7h 37m
1 stop
$201Frontier
Thu, Apr 23 - Mon, Apr 27
Frontier Logo
11:25 am - 5:49 pm
STL
-
PHL
5h 24m
1 stop
Frontier Logo
10:38 pm - 11:19 pm
PHL
-
STL
25h 41m
1 stop
$207Frontier
Wed, Apr 8 - Wed, Apr 15
Frontier Logo
8:16 pm - 5:31 am
STL
-
PHL
8h 15m
1 stop
Frontier Logo
8:41 pm - 7:21 pm
PHL
-
STL
23h 40m
1 stop
$212Frontier
Tue, Mar 31 - Sun, Apr 5
Frontier Logo
11:27 am - 10:08 pm
STL
-
PHL
9h 41m
1 stop
Frontier Logo
8:25 pm - 9:48 am
PHL
-
STL
14h 23m
1 stop
$215Frontier
Mon, May 18 - Thu, May 28
Frontier Logo
4:19 pm - 8:59 am
STL
-
PHL
15h 40m
1 stop
Frontier Logo
8:35 pm - 7:23 pm
PHL
-
STL
23h 48m
1 stop
$225Frontier
Wed, Apr 15 - Sun, Apr 19
Multiple Airlines Logo
8:23 pm - 10:53 am
STL
-
PHL
13h 30m
1 stop
Multiple Airlines Logo
7:00 am - 6:50 am
PHL
-
STL
24h 50m
1 stop
$228Multiple Airlines
Thu, May 21 - Mon, May 25
Frontier Logo
8:08 pm - 5:37 am
STL
-
PHL
8h 29m
1 stop
Frontier Logo
5:21 am - 12:21 am
PHL
-
STL
20h 00m
1 stop
$230Frontier
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.

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, Thursday 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 August, where tickets cost $277 (return) on average. On the other hand, the most expensive months are November and March, where the average cost of round-trip tickets is $493 and $463 respectively.

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 28% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 5 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 seasonFebruary
Cheapest flight$90
Best time to beat the crowds but there is an average 2% increase in price.
Most popular time to fly and prices are also 1% lower on average.
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 3 days, the lowest price for a flight from St. Louis to Philadelphia was $90 for a one-way ticket and $180 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?

    All the following airlines offer inflight Wi-Fi service on the St. Louis to Philadelphia flight route: American Airlines, JetBlue, Lufthansa, Air Canada, Alaska Airlines, and Delta.

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

    The Boeing 737 MAX 8 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 $436 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 $424 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 $346 or less one-way and $445 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 4 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 4321 reviews
8.1Boarding
8.0Comfort
7.5Entertainment
7.0Food
8.6Crew
Airline reviews

We had a 5 hour delay on the tarmac in Baltimore

2.0 MediocreDavid, Mar 2026
ALB - BWI
Read more Southwest reviews

We had a 5 hour delay on the tarmac in Baltimore

Long layover between flights to Long Island from BWI - need better coordination between flights

I elected to pay for the upgrades and found very little difference

The new seating arrangement is so over priced for what you get.

The problem with the seat assignments is that there were a lot of rows in the front that were empty but my row at the back was full. Just not so pleasant.

No food or entertainment, just a quick 40 minute flight. A little bumpy due to Santa Ana winds but pilot has no control over that. Good flight and landing!

Good but I prefer choose your own seat. With the new assigned seats they should board from the back I see no advantage to this new boarding. Just like every other airline

I realize they are still working out kinks with the new boarding process, but by the time I boarded in group 5, most of the bins were full. All airlines should better enforce small bags and jackets going under the seats until everyone has boarded.

WiFi was not working and didn’t have a beverage service

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

American Airlines did everything they could with the high Spring Break crowd. I was frustrated to be changed from 1st class to a middle seat at the back of the plane. This has happened before, not sure booking 1st class and paying the extra actually works.

I didn't end up taking this flight. I got up at 4am for a flight that was supposed to board at 6am - at 5:55am you delayed the flight to 10am. The airport is under construction so I switched to a later flight as I wasn't going to sit in the airport for 4 hours. They said the delay was due to the crew needing rest from a flight coming in late the night before - if that was the case then I think you should have delayed the flight much sooner so that passengers wouldn't get up so early and get to the airport to sit and wait.

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.

Boarding is always an ordeal. Less dogs on flights. I am highly allergic to dogs and cats. Why are there so many animals these days?

I was on a small regional flight from Detroit to Philadelphia. When we landed the outside cruise needed to turn something off with the engine, which took quite a long time. Then, when they allowed us to get off the plane it was outside. They took their time, unloading all the luggage and waited till they unloaded all the luggage before they brought it over to us. It was 9 o’clock at night freezing cold out, and there was no proactive hustle to try to get people their luggage. It was really one of the worst experiences I think I’ve ever had with American until a manager came over. I don’t think they were going to even consider pulling the luggage over to the people that had been waiting outside for at least 10 minutes in the freezing cold.

Awful. Original flight was delayed 5 hours. Had to to take a connecting flight instead of direct. Had a 4 hour layover. I missed all of my morning meetings getting in 5 hours later than I was supposed to and had to change to take a later flight the next day to get them back in which cia time another $150.

I was trying to take 2 one and a half hour one way trips and I experienced almost 20 delays over the course of those two trips. Only a few of them were due to weather the rest was disorganization

The attendants were kind and helpful. A sugar-free drink would have been very welcome.

The entertainment options were at best, fair. It was exactly the same as my outbound flight. It would have been more entertaining if there were some series from Apple TV, HBO, Showtime or other carriers for me to catch up with.

The seat cushions were very worn so they were extremely uncomfortable.

Absolutely terrible, flight was cancelled and we missed our cruise. Will never fly Spirit again.

Horrendous and unprofessional staff and will never fly spirit again

Like Spirit but bad that you have to pay for water 🙃

My flight was ultimately cancelled but the lack of updates and professionalism from the crew leading up to the cancellation announcement was frustrating for all passengers.

Delay due to personnel issues on Spirit’s end. Original departure time 9:30pm. Took off at 2:15am. Lost an entire night’s sleep bc Spirit couldn’t get a crew together. Very poor.

Sadly the flight was delayed by 4 hours due to the weather snd sir traffic control staffing. Otherwise the crew was amazing and the flight was perfect.

If there are delays, it takes less than a minute for a Spirit employee to make an announcement. It’s very simple.

I’m still waiting to get on the flight. No one knows what’s happening. The passengers have gotten no updates. We have been up all night and waiting at the airport. This is no way to operate and we should be refunded for this lack of respect for their passengers.

The plane was clean and crew was nice. Can’t speak on food as I did not have any

Flight was delayed, then undelayed, then delayed again. Gate was changed to the other side of the airport. Horrible seats with no screens. Spirit os truly awful, even for a budget option.

More inflight connection. And leg space is horrible. And the paying for baggage I'd ridiculous!!!

My flight was originally from SAT to MCO connecting from MCO to ORD. We got diverted to ATL and than Frontier staff there was sooo un helpful first they said they couldn’t give us any accommodation since our flight first got delayed that cancelled and now it’s 221am and I am still in ATL since they said they need to create a new flight my final destination is ORD and I have been delayed twice and cancelled. With no real help the frontier app didn’t work no email updates over all such a horrible experience

There's no seats that lean back with little leg space i wad uncomfortable the entire flight. Your charges for extra baggage is despicable and costly!!

Remind customers of the need to have passport or new ID for boarding.

Flight was canceled. Most upsetting was message from Kayak, stating that the flight was canceled and click with Kayak for details regarding rebook, refund details. THERE'S NO INFORMATION PROVIDED BY KAYAK EXCEPT THAT FLIGHT IS CANCELED. AND NOW THIS SURVEY TO FIND OUT HOW WAS THE FLIGHT !!!!!!!

The flight never took off and we spent 7 hours at the airport

Gate not determined until I got to the airport - hard to plan the trip to the airport.

Our flight was canceled. I will never use Kayak nor Frontier for travel again. The entire experience was a headache.

Frontier.. nickel and dime add-ons. Flight late, on time, late again, last minute gate change, arrival gate required a shuttle to the terminal. They sure keep you guessing.. if you like a little chaos and airport anxiety, this is the airline for you!

This is my second time flying with Frontier. My current experience was very favorable. The staff from the gate to the plane was friendly, warm and professional. The food options lacked in my opinion. This area needs some attention in my opinion.

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

Information on your arrival and departure airports