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Cheap flights from St. Louis to Philadelphia from $83

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from St. Louis to Philadelphia departing on 10/10. 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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Find the cheapest flights from St. Louis to Philadelphia

Cheap round-trip flights

Frontier Logo
4:00 pm - 12:59 amSTL-PHL
7h 59m1 stop
Frontier Logo
5:20 am - 10:37 amPHL-STL
6h 17m1 stop
$143Frontier
Find Deal
Mon, Oct 6 - Thu, Oct 9
Frontier Logo
1:57 pm - 12:52 amSTL-PHL
9h 55m1 stop
Frontier Logo
5:15 am - 3:04 pmPHL-STL
10h 49m1 stop
$153Frontier
Find Deal
Mon, Sep 29 - Thu, Oct 2
Frontier Logo
6:22 pm - 4:26 pmSTL-PHL
21h 04m1 stop
Frontier Logo
7:10 am - 5:27 pmPHL-STL
11h 17m1 stop
$162Frontier
Find Deal
Thu, Oct 30 - Thu, Nov 6
Frontier Logo
11:07 am - 12:19 amSTL-PHL
12h 12m1 stop
Frontier Logo
6:57 pm - 9:40 amPHL-STL
15h 43m1 stop
$163Frontier
Find Deal
Thu, Nov 6 - Sun, Nov 9
Frontier Logo
7:45 pm - 4:49 amSTL-PHL
8h 04m1 stop
Frontier Logo
5:35 pm - 11:01 pmPHL-STL
6h 26m1 stop
$166Frontier
Find Deal
Sun, Nov 16 - Wed, Nov 19
Frontier Logo
7:55 pm - 12:57 amSTL-PHL
28h 02m1 stop
Frontier Logo
5:15 am - 3:04 pmPHL-STL
10h 49m1 stop
$178Frontier
Find Deal
Wed, Oct 1 - Sun, Oct 5
Frontier Logo
8:40 pm - 4:49 amSTL-PHL
7h 09m1 stop
Frontier Logo
8:00 am - 12:09 pmPHL-STL
29h 09m1 stop
$180Frontier
Find Deal
Fri, Oct 31 - Sat, Nov 1
Frontier Logo
4:00 pm - 12:57 amSTL-PHL
7h 57m1 stop
Frontier Logo
3:07 pm - 8:37 pmPHL-STL
6h 30m1 stop
$182Frontier
Find Deal
Mon, Sep 29 - Fri, Oct 3
Multiple Airlines Logo
12:20 pm - 9:13 pmSTL-PHL
7h 53m1 stop
Multiple Airlines Logo
1:19 pm - 9:07 amPHL-STL
44h 48m2 stops
$238Multiple Airlines
Find Deal
Thu, Nov 13 - Mon, Nov 17
American Airlines Logo
6:00 am - 9:06 amSTL-PHL
2h 06mnonstop
American Airlines Logo
10:27 am - 4:11 pmPHL-STL
6h 44m1 stop
$269American Airlines
Find Deal
Thu, Nov 13 - Thu, Nov 13

Frontier flights from St. Louis to Philadelphia

Our best Frontier deals on St. Louis to Philadelphia flight tickets
Frontier
Oct 6
STL4:00 pmLambert-St Louis
7h 59m
1 stop
PHL12:59 amPhiladelphia
Oct 9
PHL5:20 amPhiladelphia
6h 17m
1 stop
STL10:37 amLambert-St Louis
$143
Find similar
Frontier
Sep 29
STL1:57 pmLambert-St Louis
9h 55m
1 stop
PHL12:52 amPhiladelphia
Oct 2
PHL5:15 amPhiladelphia
10h 49m
1 stop
STL3:04 pmLambert-St Louis
$153
Find similar
Frontier
Sep 25
STL4:00 pmLambert-St Louis
7h 57m
1 stop
PHL12:57 amPhiladelphia
Sep 28
PHL5:15 amPhiladelphia
10h 49m
1 stop
STL3:04 pmLambert-St Louis
$161
Find similar

American Airlines flights from St. Louis to Philadelphia

Our best American Airlines deals on St. Louis to Philadelphia flight tickets
American Airlines
Nov 13
STL6:00 amLambert-St Louis
2h 06m
PHL9:06 amPhiladelphia
Nov 13
PHL10:27 amPhiladelphia
6h 44m
1 stop
STL4:11 pmLambert-St Louis
$269
Find similar
American Airlines
Sep 30
STL1:03 pmLambert-St Louis
2h 20m
PHL4:23 pmPhiladelphia
Oct 4
PHL10:34 amPhiladelphia
2h 36m
STL12:10 pmLambert-St Louis
$551
Find similar
American Airlines
Sep 30
STL9:46 amLambert-St Louis
7h 44m
1 stop
PHL6:30 pmPhiladelphia
Oct 4
PHL10:34 amPhiladelphia
2h 36m
STL12:10 pmLambert-St Louis
$561
Find similar

momondo Fare Finder

 
Customize your flight search to find flights from St. Louis to Philadelphia 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 September 16, 2025.
Use the filters below to find and compare flights from St. Louis to Philadelphia that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Mon 10/6

4:00 pm-12:59 am

1 stop7h 59m

Philadelphia

Thu 10/9

5:20 am-10:37 am

1 stop6h 17m

$143

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Mon 9/29

1:57 pm-12:52 am

1 stop9h 55m

Philadelphia

Thu 10/2

5:15 am-3:04 pm

1 stop10h 49m

$153

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Thu 10/30

6:22 pm-4:26 pm

1 stop21h 04m

Philadelphia

Thu 11/6

7:10 am-5:27 pm

1 stop11h 17m

$162

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Thu 11/6

11:07 am-12:19 am

1 stop12h 12m

Philadelphia

Sun 11/9

6:57 pm-9:40 am

1 stop15h 43m

$163

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Sun 11/16

7:45 pm-4:49 am

1 stop8h 04m

Philadelphia

Wed 11/19

5:35 pm-11:01 pm

1 stop6h 26m

$166

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Wed 10/1

7:55 pm-12:57 am

1 stop28h 02m

Philadelphia

Sun 10/5

5:15 am-3:04 pm

1 stop10h 49m

$178

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Fri 10/31

8:40 pm-4:49 am

1 stop7h 09m

Philadelphia

Sat 11/1

8:00 am-12:09 pm

1 stop29h 09m

$180

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Mon 9/29

4:00 pm-12:57 am

1 stop7h 57m

Philadelphia

Fri 10/3

3:07 pm-8:37 pm

1 stop6h 30m

$182

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Thu 11/13

12:20 pm-9:13 pm

1 stop7h 53m

Philadelphia

Mon 11/17

1:19 pm-9:07 am

2 stops44h 48m

$238

St. LouisPhiladelphia

STL - PHL

STLPHL

Lambert-St Louis

Thu 11/13

6:00 am-9:06 am

Nonstop2h 06m

Philadelphia

Thu 11/13

10:27 am-4:11 pm

1 stop6h 44m

$269

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 Philadelphia from

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

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 Philadelphia?

The cheapest month to fly to Philadelphia from St. Louis is in August. Flight prices, which tend to average around $277, are often lower during this time because this is during the off-season. The month of September is another great option to travel to Philadelphia, with average flight prices from St. Louis averaging around $353.

What is the cheapest day to depart on your flight to Philadelphia?

The cheapest day to depart from St. Louis to Philadelphia is on a Thursday. Travelers who choose to depart for Philadelphia on a Thursday will often find tickets for as low as $726. On the other hand, Sunday is the most expensive day to depart from St. Louis because it is more convenient for both business and leisure travelers. As a result, prices tend to be around $992.

What is the cheapest time of day to depart on your flight to Philadelphia?

According to our data, the cheapest time of day to fly to Philadelphia is in the evening. momondo users have found flights departing from St. Louis to Philadelphia in the evening for as low as $418. Keep in mind that these prices may fluctuate based on what airline you choose and the time of year you plan to travel. In contrast, the most expensive time of day to depart to Philadelphia is at noon when prices are around $1,169.

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

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

How far in advance should I book a flight to Philadelphia?

You are more likely to see cheaper flights to Philadelphia from St. Louis when booking weeks ahead of your departure date. In general, you can expect to find flights to Philadelphia for around $392 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Philadelphia from St. Louis for as low as $328 on momondo.

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

There are 4 cabin classes available to choose from on Lambert-St Louis to Philadelphia flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Can stopping save me money on St. Louis to Philadelphia flights?

You could potentially save up to 13% on your flight if you consider stops on a St. Louis to Philadelphia flight.

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

As of September 2025, prices for St. Louis to Philadelphia flights are approximately 36% more expensive when compared to flights at the same time last year.

When to book flights from St. Louis to Philadelphia

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

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

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

Best Price Found

$211

Fastest flight time

2h 05m

Direct flights

Every day

Airports in Philadelphia

1 airport
The best one-way flight to Philadelphia from St. Louis in the past 72 hours is $211. The best round-trip flight deal from St. Louis to Philadelphia found on momondo in the last 72 hours is $428.
The fastest flight from St. Louis to Philadelphia takes 2h 05m
Direct flights go from St. Louis to Philadelphia every day.
There is 1 airport near Philadelphia: Philadelphia (PHL)
Search flight deals

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

    The distance between Lambert-St Louis and Philadelphia is about 808.1 mi. Flights usually cover this in 2h 06m, depending on flying conditions and air traffic around both airports.

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

    Prices for flights from Lambert-St Louis Airport to Philadelphia Airport are refreshed on a daily basis.

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

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

    The minimum age for a child to fly alone is five, but airlines that offer an unaccompanied minor (UNMR) service may have their own age limitations. Flight duration, scheduling, and layovers are among the considerations that may influence age limits. We recommend that you double-check with the airline you are booking with for travel from Lambert-St Louis Airport to Philadelphia Airport.

  • What documentation or ID do you need to fly to Philadelphia Airport?

    The travel and health documents you'll need for your trip to Philadelphia Airport may differ based on your itinerary and personal situation. Typically, you should have several documents on hand, such as a national ID card or driver's license and a passport that is valid for six months after your intended arrival at Philadelphia Airport. It is always advisable to seek advice from your airline or a trusted third party, such as IATA.

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

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

Best airlines flying from St. Louis to Philadelphia

Compare and see reviews for airlines that fly from St. Louis to Philadelphia with momondo
Airline
Rating
Free Cancellation
Price
Spirit AirlinesPriceFrom $106Free CancellationRating
6.3
8,019 reviews
Search Spirit Airlines flights
FrontierPriceFrom $137Free CancellationRating
5.8
3,174 reviews
Search Frontier flights
American AirlinesPriceFrom $243Free CancellationRating
7.2
10,000 reviews
Search American Airlines flights
SouthwestPriceFrom $284Free CancellationRating
8.0
4,242 reviews
Search Southwest flights

  • Southwest Flights From St. Louis to Philadelphia

    Southwest flight deals from St. Louis to Philadelphia start from $284 round-trip. Over the 10 Southwest flights for this route in a normal week, average airfare is usually $417 round-trip - but some users have found much cheaper deals with momondo.

  • American Airlines Flights From St. Louis to Philadelphia

    American Airlines (7.2/10 from 10,000 reviews) operates around 15 flights from St. Louis to Philadelphia in any given week. The average American Airlines airfare for this route is around $416, with deals from around $243 rare but found on momondo. Referenced prices are for round-trip St. Louis to Philadelphia flight searches in the last 72 hours.

Traveling to a place near Philadelphia?

Book flights to Philadelphia if you plan to visit one of these locations
Wildwood
Cape May
Rehoboth Beach
Ocean City
Wildwood Crest
King of Prussia
Dewey Beach
Reading
Newark
Cherry Hill
North Wildwood
Dover
Avalon
Lewes
Stone Harbor
Vineland
Essington
Pottstown
New Castle
West Chester

Why use momondo?

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

momondo collates all your flight options in one place and lets you filter them to find the perfect flight from St. Louis to Philadelphia. momondo saves you time and could save you money on your trip.

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

momondo does allow users to show only those flights to Philadelphia from St. Louis which offer a flexible booking policy as well as other useful filters and features.

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

momondo offers useful filters to help you find the right flight. Choose specific flight times, airports or even what payment method you prefer. We have numerous options to help you book your ideal flight from St. Louis to Philadelphia.

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

If you are not ready to book a flight from St. Louis to Philadelphia now, use our insights above to find helpful tips or alternatively set up a price alert, where momondo will track prices on flights to Philadelphia and let you know when they change.

An easier way to manage your Philadelphia 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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