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Cheap flights from Pennsylvania 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 Pennsylvania to St. Louis departing on 12/4. 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

Enter your travel dates to find the best prices.
Multiple Airlines Logo
10:45 am - 11:33 pmPIT-STL
13h 48m1 stop
Multiple Airlines Logo
12:06 pm - 11:07 pmSTL-PIT
10h 01m1 stop
$175Multiple Airlines
Find Deal
Wed, Jan 21 - Sat, Jan 24
Frontier Logo
3:48 pm - 10:33 pmPHL-STL
7h 45m1 stop
Frontier Logo
3:43 pm - 12:51 amSTL-PHL
8h 08m1 stop
$195Frontier
Find Deal
Wed, Jan 7 - Sun, Jan 11
Multiple Airlines Logo
5:15 am - 1:52 pmPHL-STL
9h 37m1 stop
Multiple Airlines Logo
3:30 pm - 10:00 amSTL-PHL
17h 30m1 stop
$197Multiple Airlines
Find Deal
Sun, Dec 7 - Wed, Dec 10
Frontier Logo
2:06 pm - 10:33 pmPHL-STL
9h 27m1 stop
Frontier Logo
3:30 pm - 12:40 amSTL-PHL
8h 10m1 stop
$198Frontier
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Mon, Dec 8 - Thu, Dec 11
Delta Logo
10:54 am - 2:48 pmPIT-STL
4h 54m1 stop
Delta Logo
6:00 am - 12:43 pmSTL-PIT
5h 43m1 stop
$207Delta
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Tue, Jan 13 - Wed, Jan 14
American Airlines Logo
6:38 am - 1:14 pmPIT-STL
7h 36m1 stop
American Airlines Logo
6:00 am - 5:09 pmSTL-PIT
10h 09m1 stop
$220American Airlines
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Thu, Dec 18 - Thu, Dec 25
United Airlines Logo
10:27 am - 5:18 pmPIT-STL
7h 51m1 stop
United Airlines Logo
8:30 am - 2:04 pmSTL-PIT
4h 34m1 stop
$242United Airlines
Find Deal
Wed, Feb 4 - Thu, Feb 5
American Airlines Logo
9:41 am - 4:19 pmDCA-STL
7h 38m1 stop
American Airlines Logo
9:54 am - 12:59 pmSTL-DCA
2h 05mnonstop
$245American Airlines
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Sat, Dec 13 - Sat, Jan 17
United Airlines Logo
8:20 am - 12:29 pmIAD-STL
5h 09m1 stop
United Airlines Logo
12:44 pm - 3:55 pmSTL-IAD
2h 11mnonstop
$245United Airlines
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Wed, Jan 28 - Tue, Feb 3
Delta Logo
6:00 am - 9:24 amMDT-STL
4h 24m1 stop
Delta Logo
5:59 pm - 11:02 pmSTL-MDT
4h 03m1 stop
$249Delta
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Sun, Dec 21 - Sun, Jan 4

United Airlines flights from Pennsylvania to St. Louis

Our best United Airlines deals on Pennsylvania to St. Louis flight tickets
United Airlines
Feb 4
PIT10:27 amPittsburgh
7h 51m
1 stop
STL5:18 pmLambert-St Louis
Feb 5
STL8:30 amLambert-St Louis
4h 34m
1 stop
PIT2:04 pmPittsburgh
$242
Find similar
United Airlines
Jan 28
IAD8:20 amWashington, D.C. Dulles Intl
5h 09m
1 stop
STL12:29 pmLambert-St Louis
Feb 3
STL12:44 pmLambert-St Louis
2h 11m
IAD3:55 pmWashington, D.C. Dulles Intl
$245
Find similar
United Airlines
Feb 19
IAD8:15 amWashington, D.C. Dulles Intl
5h 10m
1 stop
STL12:25 pmLambert-St Louis
Feb 21
STL6:30 amLambert-St Louis
4h 19m
1 stop
IAD11:49 amWashington, D.C. Dulles Intl
$257
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Spirit Airlines flights from Pennsylvania to St. Louis

Our best Spirit Airlines deals on Pennsylvania to St. Louis flight tickets
Spirit Airlines
Dec 11
PHL5:15 amPhiladelphia
9h 37m
1 stop
STL1:52 pmLambert-St Louis
Dec 14
STL2:47 pmLambert-St Louis
7h 29m
1 stop
PHL11:16 pmPhiladelphia
$266
Find similar
Spirit Airlines
Dec 4
EWR5:46 amNewark
9h 06m
1 stop
STL1:52 pmLambert-St Louis
Dec 7
STL2:47 pmLambert-St Louis
21h 13m
3 stops
EWR1:00 pmNewark
$303
Find similar
Spirit Airlines
Dec 17
EWR6:00 amNewark
29h 56m
3 stops
STL10:56 amLambert-St Louis
Dec 30
STL11:51 amLambert-St Louis
18h 05m
2 stops
EWR6:56 amNewark
$320
Find similar

momondo Fare Finder

 
Customize your flight search to find flights from Pennsylvania 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 November 20, 2025.
Use the filters below to find and compare flights from Pennsylvania to St. Louis that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

PittsburghSt. Louis

PIT - STL

PITSTL

Pittsburgh

Wed 1/21

10:45 am-11:33 pm

1 stop13h 48m

Lambert-St Louis

Sat 1/24

12:06 pm-11:07 pm

1 stop10h 01m

$175

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Wed 1/7

3:48 pm-10:33 pm

1 stop7h 45m

Lambert-St Louis

Sun 1/11

3:43 pm-12:51 am

1 stop8h 08m

$195

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Sun 12/7

5:15 am-1:52 pm

1 stop9h 37m

Lambert-St Louis

Wed 12/10

3:30 pm-10:00 am

1 stop17h 30m

$197

PhiladelphiaSt. Louis

PHL - STL

PHLSTL

Philadelphia

Mon 12/8

2:06 pm-10:33 pm

1 stop9h 27m

Lambert-St Louis

Thu 12/11

3:30 pm-12:40 am

1 stop8h 10m

$198

PittsburghSt. Louis

PIT - STL

PITSTL

Pittsburgh

Tue 1/13

10:54 am-2:48 pm

1 stop4h 54m

Lambert-St Louis

Wed 1/14

6:00 am-12:43 pm

1 stop5h 43m

$207

PittsburghSt. Louis

PIT - STL

PITSTL

Pittsburgh

Thu 12/18

6:38 am-1:14 pm

1 stop7h 36m

Lambert-St Louis

Thu 12/25

6:00 am-5:09 pm

1 stop10h 09m

$220

PittsburghSt. Louis

PIT - STL

PITSTL

Pittsburgh

Wed 2/4

10:27 am-5:18 pm

1 stop7h 51m

Lambert-St Louis

Thu 2/5

8:30 am-2:04 pm

1 stop4h 34m

$242

Washington, D.C.St. Louis

DCA - STL

DCASTL

Washington, D.C. Reagan-National

Sat 12/13

9:41 am-4:19 pm

1 stop7h 38m

Lambert-St Louis

Sat 1/17

9:54 am-12:59 pm

Nonstop2h 05m

$245

Washington, D.C.St. Louis

IAD - STL

IADSTL

Washington, D.C. Dulles Intl

Wed 1/28

8:20 am-12:29 pm

1 stop5h 09m

Lambert-St Louis

Tue 2/3

12:44 pm-3:55 pm

Nonstop2h 11m

$245

HarrisburgSt. Louis

MDT - STL

MDTSTL

Harrisburg

Sun 12/21

6:00 am-9:24 am

1 stop4h 24m

Lambert-St Louis

Sun 1/4

5:59 pm-11:02 pm

1 stop4h 03m

$249

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 Pennsylvania 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 Pennsylvania 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 Pennsylvania 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 $388. 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 $479. 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 Pennsylvania in the afternoon is the least expensive time of day to depart. momondo users have found prices as low as $384 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 $428 per ticket.

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

Fly from Philadelphia to Lambert-St Louis for the best Pennsylvania - 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 Pennsylvania when booking weeks ahead of your departure date. In general, you can expect to find flights to St. Louis for around $403 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to St. Louis from Pennsylvania for as low as $338 on momondo.

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

There are 2 cabin classes available to choose from on Pennsylvania 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.

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

You could potentially save up to 25% on your flight if you consider stops on a Pennsylvania to St. Louis flight.

Cheap Pennsylvania to St. Louis flight deals and tips

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

Best Price Found

$157

Fastest flight time

1h 45m

Direct flights

Every day

Airports in St. Louis

1 airport
The best one-way flight to St. Louis from Pennsylvania in the past 72 hours is $157. The best round-trip flight deal from Pennsylvania to St. Louis found on momondo in the last 72 hours is $325.
The fastest flight from Pennsylvania to St. Louis takes 1h 45m
Direct flights go from Pennsylvania to St. Louis every day.
There is 1 airport near St. Louis: Lambert-St Louis (STL)
Search flight deals

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

    Prices for flights from Pennsylvania to Lambert-St Louis Airport refresh daily.

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

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

    Although the minimum age for a child to fly alone is five, airlines that offer an unaccompanied minor (UMNR) service may have their own age limits, which could be impacted by factors such as flight length, timing, and layovers. It is recommended that you verify with the airline you are booking with for travel from Pennsylvania to Lambert-St Louis Airport.

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

    The required travel and health documents for your Lambert-St Louis Airport trip may vary depending on your itinerary and personal circumstances. As a general rule, you should carry multiple documents, including a national ID card or driver's license and a passport valid for six months after your intended arrival at Lambert-St Louis Airport. We recommend that you seek guidance from your airline or a reliable third party such as IATA.

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

Best airlines flying from Pennsylvania to St. Louis

Compare and see reviews for airlines that fly from Pennsylvania to St. Louis with momondo
Airline
Rating
Free Cancellation
Price
Spirit AirlinesPriceFrom $95Free CancellationRating
6.3
8,156 reviews
Search Spirit Airlines flights
FrontierPriceFrom $130Free CancellationRating
5.8
3,106 reviews
Search Frontier flights
American AirlinesPriceFrom $171Free CancellationRating
7.2
11,045 reviews
Search American Airlines flights
SouthwestPriceFrom $241Free CancellationRating
8.0
4,249 reviews
Search Southwest flights
United AirlinesPriceFrom $248Free CancellationRating
7.4
9,029 reviews
Search United Airlines flights
DeltaPriceFrom $248Free CancellationRating
7.9
8,002 reviews
Search Delta flights

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
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 Pennsylvania to St. Louis?

momondo compares prices from hundreds of airlines and agents so you can find and book the best deal on flights from Pennsylvania to St. Louis. Millions of users trust and use momondo every year so you are in good hands.

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

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

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

Once you have performed a search in the form on the page, momondo provides useful filters and insights. We can show you the cheapest days and times to fly as well as help filter your options to help you make an informed choice when booking flights to St. Louis from Pennsylvania.

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

Yes momondo offers price alerts on flights to St. Louis from Pennsylvania. After performing a search on this page you should be able to see the price alert set up feature. Simply provide a valid email address and momondo will instantly alert you when prices change.

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