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Cheap flights from Philadelphia to St. Louis from $55

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from Philadelphia to St. Louis departing on 11/13. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.
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0 bags

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Cheap round-trip flights

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Frontier Logo
10:00 pm - 9:45 amPHL-STL
12h 45m1 stop
Frontier Logo
4:27 pm - 12:40 amSTL-PHL
7h 13m1 stop
$300Frontier
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Sun, Dec 21 - Wed, Dec 31
Frontier Logo
10:00 pm - 9:45 amPHL-STL
12h 45m1 stop
Frontier Logo
10:40 am - 12:26 amSTL-PHL
12h 46m2 stops
$302Frontier
Find Deal
Sun, Dec 21 - Mon, Dec 29
American Airlines Logo
6:00 am - 2:09 pmPHL-STL
9h 09m1 stop
American Airlines Logo
5:30 am - 8:47 amSTL-PHL
2h 17mnonstop
$303American Airlines
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Wed, Dec 24 - Tue, Dec 30
Delta Logo
6:00 am - 9:24 amPHL-STL
4h 24m1 stop
Delta Logo
7:00 am - 12:42 pmSTL-PHL
4h 42m1 stop
$327Delta
Find Deal
Thu, Dec 25 - Thu, Jan 1
American Airlines Logo
10:50 am - 12:31 pmPHL-STL
2h 41mnonstop
American Airlines Logo
5:30 am - 8:47 amSTL-PHL
2h 17mnonstop
$329American Airlines
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Wed, Dec 24 - Tue, Dec 30
Delta Logo
5:40 am - 11:04 amPHL-STL
6h 24m1 stop
Delta Logo
6:35 am - 11:38 amSTL-PHL
4h 03m1 stop
$340Delta
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Sat, Jan 17 - Sat, Jan 24
Spirit Airlines Logo
8:54 pm - 8:57 amPHL-STL
13h 03m1 stop
Spirit Airlines Logo
11:08 am - 2:05 pmSTL-PHL
25h 57m3 stops
$343Spirit Airlines
Find Deal
Fri, Nov 21 - Sun, Nov 23
Spirit Airlines Logo
6:15 am - 8:57 amPHL-STL
27h 42m2 stops
Spirit Airlines Logo
11:08 am - 2:05 pmSTL-PHL
25h 57m3 stops
$349Spirit Airlines
Find Deal
Fri, Nov 21 - Sun, Nov 23
Southwest Logo
8:05 am - 9:35 amPHL-STL
2h 30mnonstop
Southwest Logo
8:25 am - 11:30 amSTL-PHL
2h 05mnonstop
$352Southwest
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Wed, Dec 10 - Sat, Dec 13
Southwest Logo
1:50 pm - 3:20 pmPHL-STL
2h 30mnonstop
Southwest Logo
5:45 pm - 8:50 pmSTL-PHL
2h 05mnonstop
$353Southwest
Find Deal
Tue, Dec 2 - Sat, Dec 6

Southwest flights from Philadelphia to St. Louis

Our best Southwest deals on Philadelphia to St. Louis flight tickets
Southwest
Dec 10
PHL8:05 amPhiladelphia
2h 30m
STL9:35 amLambert-St Louis
Dec 13
STL8:25 amLambert-St Louis
2h 05m
PHL11:30 amPhiladelphia
$352
Find similar
Southwest
Dec 2
PHL1:50 pmPhiladelphia
2h 30m
STL3:20 pmLambert-St Louis
Dec 6
STL5:45 pmLambert-St Louis
2h 05m
PHL8:50 pmPhiladelphia
$353
Find similar
Southwest
Nov 19
PHL8:05 amPhiladelphia
2h 30m
STL9:35 amLambert-St Louis
Nov 25
STL2:15 pmLambert-St Louis
3h 35m
1 stop
PHL6:50 pmPhiladelphia
$363
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Spirit Airlines flights from Philadelphia to St. Louis

Our best Spirit Airlines deals on Philadelphia to St. Louis flight tickets
Spirit Airlines
Nov 21
PHL8:54 pmPhiladelphia
13h 03m
1 stop
STL8:57 amLambert-St Louis
Nov 23
STL11:08 amLambert-St Louis
25h 57m
3 stops
PHL2:05 pmPhiladelphia
$343
Find similar
Spirit Airlines
Nov 21
PHL6:15 amPhiladelphia
27h 42m
2 stops
STL8:57 amLambert-St Louis
Nov 23
STL11:08 amLambert-St Louis
25h 57m
3 stops
PHL2:05 pmPhiladelphia
$349
Find similar
Spirit Airlines
Nov 12
PHL1:57 pmPhiladelphia
29h 00m
3 stops
STL5:57 pmLambert-St Louis
Nov 16
STL6:21 pmLambert-St Louis
14h 09m
1 stop
PHL9:30 amPhiladelphia
$379
Find similar

momondo Fare Finder

 
Customize your flight search to find flights from Philadelphia to St. Louis 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, momondo users made 832,500 searches. Data last updated October 30, 2025.
Use the filters below to find and compare flights from Philadelphia to St. Louis that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Sun 12/21

10:00 pm-9:45 am

1 stop12h 45m

Lambert-St Louis

Wed 12/31

4:27 pm-12:40 am

1 stop7h 13m

$300

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Sun 12/21

10:00 pm-9:45 am

1 stop12h 45m

Lambert-St Louis

Mon 12/29

10:40 am-12:26 am

2 stops12h 46m

$302

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Wed 12/24

6:00 am-2:09 pm

1 stop9h 09m

Lambert-St Louis

Tue 12/30

5:30 am-8:47 am

Nonstop2h 17m

$303

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Thu 12/25

6:00 am-9:24 am

1 stop4h 24m

Lambert-St Louis

Thu 1/1

7:00 am-12:42 pm

1 stop4h 42m

$327

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Wed 12/24

10:50 am-12:31 pm

Nonstop2h 41m

Lambert-St Louis

Tue 12/30

5:30 am-8:47 am

Nonstop2h 17m

$329

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Sat 1/17

5:40 am-11:04 am

1 stop6h 24m

Lambert-St Louis

Sat 1/24

6:35 am-11:38 am

1 stop4h 03m

$340

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Fri 11/21

8:54 pm-8:57 am

1 stop13h 03m

Lambert-St Louis

Sun 11/23

11:08 am-2:05 pm

3 stops25h 57m

$343

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Fri 11/21

6:15 am-8:57 am

2 stops27h 42m

Lambert-St Louis

Sun 11/23

11:08 am-2:05 pm

3 stops25h 57m

$349

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Wed 12/10

8:05 am-9:35 am

Nonstop2h 30m

Lambert-St Louis

Sat 12/13

8:25 am-11:30 am

Nonstop2h 05m

$352

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Tue 12/2

1:50 pm-3:20 pm

Nonstop2h 30m

Lambert-St Louis

Sat 12/6

5:45 pm-8:50 pm

Nonstop2h 05m

$353

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 20 resultsSorted by cheapest first
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See travel insights to St. Louis from

How to get the cheapest flight ticket from Philadelphia to St. Louis

Look no further. We've gone through all the searches for this route on momondo so you have the important information and insights to find the cheapest flight ticket for your trip

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

In general, September is the cheapest month to fly from Philadelphia to St. Louis. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $317. The month of August is another great option to travel to St. Louis, with average flight prices from Philadelphia averaging around $320.

What is the cheapest day to depart on your flight to St. Louis?

The cheapest day to depart on your flight to St. Louis is on a Wednesday when prices can be found for as low as $389. This is often the case because there is less demand to fly during this day of the week. If your travel schedule is flexible, try to avoid departing on a Sunday because tickets tend to average around $480. These prices are subject to change though, so be sure to set up a Price Alert for flights to St. Louis.

What is the cheapest time of day to depart on your flight to St. Louis?

Flying to St. Louis from Philadelphia in the afternoon is the least expensive time of day to depart. momondo users have found prices as low as $385 when looking at flights departing in the afternoon. In the evening is when there is more demand to fly to St. Louis, so prices are often more expensive at around $427 per ticket.

What is the cheapest Philadelphia to Lambert-St Louis flight route?

Fly from Philadelphia to Lambert-St Louis for the best Philadelphia - Lambert-St Louis flight prices

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

You are more likely to see cheaper flights to St. Louis from Philadelphia when booking weeks ahead of your departure date. In general, you can expect to find flights to St. Louis for around $401 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to St. Louis from Philadelphia for as low as $338 on momondo.

What cabin class options are available on Philadelphia to Lambert-St Louis flights?

There are 2 cabin classes available to choose from on Philadelphia to Lambert-St Louis flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

How have Philadelphia to St. Louis flight prices changed over time?

As of October 2025, prices for Philadelphia to St. Louis flights are approximately 69% more expensive when compared to flights at the same time last year.

When to book flights from Philadelphia to St. Louis

Are you open to changing your travel dates? Check out the ideal times to fly from Philadelphia to St. Louis according to our flight data. Find out which month and days have the cheapest flights.
Estimated round-trip price

Cheap Philadelphia to St. Louis (PHL to STL) flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from Philadelphia to St. Louis

Best Price Found

$175

Fastest flight time

2h 28m

Direct flights

Every day

Airports in St. Louis

1 airport
The best one-way flight to St. Louis from Philadelphia in the past 72 hours is $175. The best round-trip flight deal from Philadelphia to St. Louis found on momondo in the last 72 hours is $373.
The fastest flight from Philadelphia to St. Louis takes 2h 28m
Direct flights go from Philadelphia to St. Louis every day.
There is 1 airport near St. Louis: Lambert-St Louis (STL)
Search flight deals

  • How far is Philadelphia to Lambert-St Louis by plane?

    There are 808.1 mi between Philadelphia and Lambert-St Louis. Typically, this will take 2h 30m by plane in normal conditions.

  • When did momondo last update prices for flights from Philadelphia Airport to Lambert-St Louis Airport?

    Prices for flights from Philadelphia Airport to Lambert-St Louis Airport were last updated today.

  • How many operators does momondo search for flights from Philadelphia Airport to Lambert-St Louis Airport?

  • How old do you have to be to fly from Philadelphia Airport to Lambert-St Louis Airport?

    The minimum age for a child to fly alone is five, but airlines offering an unaccompanied minor (UNMR) service may have their age restrictions, such as regulations concerning flight duration, timing, and layovers. It is recommended that you verify with the airline you are booking with for travel from Philadelphia Airport to Lambert-St Louis Airport.

  • What documentation or ID do you need to fly to Lambert-St Louis Airport?

    The travel and health documents required for your trip to Lambert-St Louis Airport can vary based on your itinerary and personal situation. As a rule, consider having multiple documents such as a national ID card or driver’s license, and a passport valid for six-months after you plan to arrive at Lambert-St Louis Airport. We always recommend checking with your airline or a trusted third party such as IATA to get advice.

  • What is the most popular plane model from Philadelphia to St. Louis?

  • What is the most popular airline from Philadelphia to St. Louis?

Best airlines flying from Philadelphia to St. Louis

Compare and see reviews for airlines that fly from Philadelphia to St. Louis with momondo
Airline
Rating
Free Cancellation
Price
Spirit AirlinesPriceFrom $95Free CancellationRating
6.3
8,116 reviews
Search Spirit Airlines flights
FrontierPriceFrom $130Free CancellationRating
5.8
3,122 reviews
Search Frontier flights
American AirlinesPriceFrom $242Free CancellationRating
7.2
11,035 reviews
Search American Airlines flights
DeltaPriceFrom $259Free CancellationRating
7.9
7,998 reviews
Search Delta flights
SouthwestPriceFrom $263Free CancellationRating
8.0
4,243 reviews
Search Southwest flights

  • Southwest Flights From Philadelphia to St. Louis

    The lowest priced Southwest flight from Philadelphia to St. Louis from the last 72 hours was $263. Generally, Southwest has 2 flights on this route every week with an average price of $421. Southwest is rated 8.0/10 by our users.

  • American Airlines Flights From Philadelphia to St. Louis

    $242 is the best American Airlines flight deal from Philadelphia to St. Louis found on momondo over the last 72 hours. The average American Airlines ticket price found was closer to $417, however, with flight time and availability significantly affecting the price. American Airlines (7.2/10 from 11,035 user reviews) flies into St. Louis from Philadelphia 3 times in an average week so prices can vary.

Traveling to a place near St. Louis?

Book flights to St. Louis if you plan to visit one of these locations
St. Charles
Chesterfield
Hermann
Fairview Heights
Maryland Heights
Florissant
O'Fallon
Wentzville
Fenton
Collinsville
St. Peters
Alton
Farmington
Festus
Glencoe
Edwardsville
Clayton
Eureka
Litchfield
Shrewsbury

Why use momondo?

Why should I use momondo to find a flight deal from Philadelphia to St. Louis?

We help find the flight that best suits your needs, momondo compares prices from hundreds of airlines and travel agents and helps you filter them to find the best flight from Philadelphia to St. Louis for you.

Can I find flights from Philadelphia to St. Louis with flexible booking policies on momondo?

Yes. All flights to St. Louis from Philadelphia on momondo can be compared and filtered by various policies on offer, including flexible booking.

How can momondo help me find flights from Philadelphia to St. Louis?

momondo provides multiple filters to help you find the best flight to St. Louis from Philadelphia. Filter by price, airline, airports, cabin, aircraft, payment method, number of stops and more.

I’m not ready to book a flight from Philadelphia to St. Louis right now. Can momondo alert me if prices change?

If you are simply researching potential flights to St. Louis, momondo offers a useful price alert feature which will track prices for flights to St. Louis from Philadelphia and alert you when they change.

An easier way to manage your St. Louis trip

We make it super easy to schedule, organize and travel with friends or family. Trips is free — and available to use no matter where you book.
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