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Cheap flights from Philadelphia to St. Louis from $81

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 10/18. 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 Philadelphia to St. Louis

Cheap round-trip flights

Frontier Logo
5:15 am - 3:04 pmPHL-STL
10h 49m1 stop
Frontier Logo
6:05 pm - 1:07 amSTL-PHL
6h 02m1 stop
$221Frontier
Find Deal
Sun, Oct 5 - Sun, Oct 12
Frontier Logo
7:25 am - 8:37 pmPHL-STL
14h 12m2 stops
Frontier Logo
10:39 am - 7:35 amSTL-PHL
19h 56m2 stops
$222Frontier
Find Deal
Fri, Oct 3 - Sun, Oct 5
Multiple Airlines Logo
9:50 pm - 9:40 amPHL-STL
12h 50m1 stop
Multiple Airlines Logo
10:57 am - 11:52 amSTL-PHL
23h 55m1 stop
$224Multiple Airlines
Find Deal
Sat, Sep 27 - Thu, Oct 9
Multiple Airlines Logo
12:00 pm - 9:40 amPHL-STL
22h 40m1 stop
Multiple Airlines Logo
10:57 am - 11:52 amSTL-PHL
23h 55m1 stop
$225Multiple Airlines
Find Deal
Wed, Oct 1 - Thu, Oct 9
Frontier Logo
3:07 pm - 8:37 pmPHL-STL
6h 30m1 stop
Frontier Logo
10:39 am - 7:35 amSTL-PHL
19h 56m2 stops
$226Frontier
Find Deal
Fri, Oct 3 - Sun, Oct 5
Frontier Logo
5:12 pm - 9:07 amPHL-STL
16h 55m2 stops
Frontier Logo
10:18 am - 1:48 amSTL-PHL
14h 30m1 stop
$228Frontier
Find Deal
Fri, Oct 24 - Mon, Oct 27
Frontier Logo
7:25 am - 8:37 pmPHL-STL
14h 12m2 stops
Frontier Logo
7:55 pm - 4:25 pmSTL-PHL
19h 30m2 stops
$230Frontier
Find Deal
Fri, Oct 3 - Mon, Oct 6
Spirit Airlines Logo
12:00 pm - 9:40 amPHL-STL
22h 40m1 stop
Spirit Airlines Logo
10:57 am - 11:59 pmSTL-PHL
12h 02m1 stop
$263Spirit Airlines
Find Deal
Wed, Oct 1 - Sun, Oct 5
Spirit Airlines Logo
9:50 pm - 9:40 amPHL-STL
12h 50m1 stop
Spirit Airlines Logo
10:57 am - 11:59 pmSTL-PHL
12h 02m1 stop
$265Spirit Airlines
Find Deal
Sat, Sep 27 - Thu, Oct 9
Spirit Airlines Logo
2:07 pm - 9:40 amPHL-STL
20h 33m2 stops
Spirit Airlines Logo
10:57 am - 11:59 pmSTL-PHL
12h 02m1 stop
$277Spirit Airlines
Find Deal
Wed, Oct 1 - Thu, Oct 9

Frontier flights from Philadelphia to St. Louis

Our best Frontier deals on Philadelphia to St. Louis flight tickets
Frontier
Oct 5
PHL5:15 amPhiladelphia
10h 49m
1 stop
STL3:04 pmLambert-St Louis
Oct 12
STL6:05 pmLambert-St Louis
6h 02m
1 stop
PHL1:07 amPhiladelphia
$221
Find similar
Frontier
Oct 3
PHL7:25 amPhiladelphia
14h 12m
2 stops
STL8:37 pmLambert-St Louis
Oct 5
STL10:39 amLambert-St Louis
19h 56m
2 stops
PHL7:35 amPhiladelphia
$222
Find similar
Frontier
Oct 3
PHL3:07 pmPhiladelphia
6h 30m
1 stop
STL8:37 pmLambert-St Louis
Oct 5
STL10:39 amLambert-St Louis
19h 56m
2 stops
PHL7:35 amPhiladelphia
$226
Find similar

Spirit Airlines flights from Philadelphia to St. Louis

Our best Spirit Airlines deals on Philadelphia to St. Louis flight tickets
Spirit Airlines
Oct 1
PHL12:00 pmPhiladelphia
22h 40m
1 stop
STL9:40 amLambert-St Louis
Oct 5
STL10:57 amLambert-St Louis
12h 02m
1 stop
PHL11:59 pmPhiladelphia
$263
Find similar
Spirit Airlines
Sep 27
PHL9:50 pmPhiladelphia
12h 50m
1 stop
STL9:40 amLambert-St Louis
Oct 9
STL10:57 amLambert-St Louis
12h 02m
1 stop
PHL11:59 pmPhiladelphia
$265
Find similar
Spirit Airlines
Oct 1
PHL2:07 pmPhiladelphia
20h 33m
2 stops
STL9:40 amLambert-St Louis
Oct 9
STL10:57 amLambert-St Louis
12h 02m
1 stop
PHL11:59 pmPhiladelphia
$277
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 September 17, 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 10/5

5:15 am-3:04 pm

1 stop10h 49m

Lambert-St Louis

Sun 10/12

6:05 pm-1:07 am

1 stop6h 02m

$221

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Fri 10/3

7:25 am-8:37 pm

2 stops14h 12m

Lambert-St Louis

Sun 10/5

10:39 am-7:35 am

2 stops19h 56m

$222

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Sat 9/27

9:50 pm-9:40 am

1 stop12h 50m

Lambert-St Louis

Thu 10/9

10:57 am-11:52 am

1 stop23h 55m

$224

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Wed 10/1

12:00 pm-9:40 am

1 stop22h 40m

Lambert-St Louis

Thu 10/9

10:57 am-11:52 am

1 stop23h 55m

$225

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Fri 10/3

3:07 pm-8:37 pm

1 stop6h 30m

Lambert-St Louis

Sun 10/5

10:39 am-7:35 am

2 stops19h 56m

$226

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Fri 10/24

5:12 pm-9:07 am

2 stops16h 55m

Lambert-St Louis

Mon 10/27

10:18 am-1:48 am

1 stop14h 30m

$228

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Fri 10/3

7:25 am-8:37 pm

2 stops14h 12m

Lambert-St Louis

Mon 10/6

7:55 pm-4:25 pm

2 stops19h 30m

$230

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Wed 10/1

12:00 pm-9:40 am

1 stop22h 40m

Lambert-St Louis

Sun 10/5

10:57 am-11:59 pm

1 stop12h 02m

$263

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Sat 9/27

9:50 pm-9:40 am

1 stop12h 50m

Lambert-St Louis

Thu 10/9

10:57 am-11:59 pm

1 stop12h 02m

$265

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Wed 10/1

2:07 pm-9:40 am

2 stops20h 33m

Lambert-St Louis

Thu 10/9

10:57 am-11:59 pm

1 stop12h 02m

$277

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, August 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 $320. The month of September is another great option to travel to St. Louis, with average flight prices from Philadelphia averaging around $355.

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 $391. 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 $473. 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 $386 when looking at flights departing in the afternoon. At noon is when there is more demand to fly to St. Louis, so prices are often more expensive at around $432 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 $400 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 $343 on momondo.

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

There are 3 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 September 2025, prices for Philadelphia to St. Louis flights are approximately 25% 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

$219

Fastest flight time

2h 20m

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 $219. The best round-trip flight deal from Philadelphia to St. Louis found on momondo in the last 72 hours is $282.
The fastest flight from Philadelphia to St. Louis takes 2h 20m
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 5h 56m 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
8,023 reviews
Search Spirit Airlines flights
FrontierPriceFrom $119Free CancellationRating
5.8
3,173 reviews
Search Frontier flights
American AirlinesPriceFrom $243Free CancellationRating
7.2
10,000 reviews
Search American Airlines flights
DeltaPriceFrom $259Free CancellationRating
7.9
7,961 reviews
Search Delta flights
SouthwestPriceFrom $266Free CancellationRating
8.0
4,242 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 $266. Generally, Southwest has 10 flights on this route every week with an average price of $418. Southwest is rated 8.0/10 by our users.

  • American Airlines Flights From Philadelphia to St. Louis

    $243 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 $416, however, with flight time and availability significantly affecting the price. American Airlines (7.2/10 from 10,000 user reviews) flies into St. Louis from Philadelphia 14 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
Florissant
Maryland Heights
O'Fallon
Fenton
Collinsville
Wentzville
Alton
St. Peters
Farmington
Festus
Glencoe
Clayton
Edwardsville
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

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