Cheap Flights from Philadelphia International to St Louis

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Compare Philadelphia International to St Louis flight deals

Find the cheapest month or even day of the year to fly to St Louis

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Flight deals from Philadelphia International to St Louis

Looking for a cheap last-minute deal or the best return flight from Philadelphia International Airport to St Louis Airport? If you want to travel next month, return fares start from $153. Find the lowest prices on one-way and return tickets right here.

St Louis.$153 per passenger.Departing Wed, 14 Oct, returning Mon, 19 Oct.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Philadelphia International on Wed, 14 Oct, arriving in St Louis.Inbound indirect flight with Frontier Airlines, departs from St Louis on Mon, 19 Oct, arriving in Philadelphia International.Price includes taxes and charges.From $153, select.

St Louis.$154 per passenger.Departing Wed, 4 Nov, returning Mon, 9 Nov.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Philadelphia International on Wed, 4 Nov, arriving in St Louis.Inbound indirect flight with Frontier Airlines, departs from St Louis on Mon, 9 Nov, arriving in Philadelphia International.Price includes taxes and charges.From $154, select.

St Louis.$187 per passenger.Departing Wed, 11 Nov, returning Wed, 2 Dec.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Philadelphia International on Wed, 11 Nov, arriving in St Louis.Inbound indirect flight with Frontier Airlines, departs from St Louis on Wed, 2 Dec, arriving in Philadelphia International.Price includes taxes and charges.From $187, select.

St Louis.$246 per passenger.Departing Wed, 30 Sep, returning Fri, 2 Oct.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Philadelphia International on Wed, 30 Sep, arriving in St Louis.Inbound indirect flight with Frontier Airlines, departs from St Louis on Fri, 2 Oct, arriving in Philadelphia International.Price includes taxes and charges.From $246, select.

St Louis.$278 per passenger.Departing Wed, 21 Oct, returning Wed, 11 Nov.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Philadelphia International on Wed, 21 Oct, arriving in St Louis.Inbound indirect flight with Frontier Airlines, departs from St Louis on Wed, 11 Nov, arriving in Philadelphia International.Price includes taxes and charges.From $278, select.

St Louis.$391 per passenger.Departing Thu, 10 Dec, returning Fri, 11 Dec.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Philadelphia International on Thu, 10 Dec, arriving in St Louis.Inbound indirect flight with Frontier Airlines, departs from St Louis on Fri, 11 Dec, arriving in Philadelphia International.Price includes taxes and charges.From $391, select.

St Louis.$440 per passenger.Departing Tue, 20 Oct, returning Thu, 22 Oct.Return flight with Southwest Airlines.Outbound direct flight with Southwest Airlines departs from Philadelphia International on Tue, 20 Oct, arriving in St Louis.Inbound direct flight with Southwest Airlines departs from St Louis on Thu, 22 Oct, arriving in Philadelphia International.Price includes taxes and charges.From $440, select.

St Louis.$441 per passenger.Departing Sat, 31 Oct, returning Tue, 3 Nov.Return flight with Southwest Airlines.Outbound direct flight with Southwest Airlines departs from Philadelphia International on Sat, 31 Oct, arriving in St Louis.Inbound direct flight with Southwest Airlines departs from St Louis on Tue, 3 Nov, arriving in Philadelphia International.Price includes taxes and charges.From $441, select.

St Louis.$441 per passenger.Departing Wed, 4 Nov, returning Mon, 9 Nov.Return flight with Southwest Airlines.Outbound direct flight with Southwest Airlines departs from Philadelphia International on Wed, 4 Nov, arriving in St Louis.Inbound direct flight with Southwest Airlines departs from St Louis on Mon, 9 Nov, arriving in Philadelphia International.Price includes taxes and charges.From $441, select.

St Louis.$473 per passenger.Departing Thu, 11 Feb, returning Thu, 18 Feb.Return flight with United.Outbound indirect flight with United, departs from Philadelphia International on Thu, 11 Feb, arriving in St Louis.Inbound indirect flight with United, departs from St Louis on Thu, 18 Feb, arriving in Philadelphia International.Price includes taxes and charges.From $473, select.

St Louis.$477 per passenger.Departing Wed, 30 Sep, returning Fri, 2 Oct.Return flight with Southwest Airlines.Outbound direct flight with Southwest Airlines departs from Philadelphia International on Wed, 30 Sep, arriving in St Louis.Inbound direct flight with Southwest Airlines departs from St Louis on Fri, 2 Oct, arriving in Philadelphia International.Price includes taxes and charges.From $477, select.

St Louis.$510 per passenger.Departing Tue, 1 Dec, returning Fri, 1 Jan.Return flight with Delta.Outbound indirect flight with Delta, departs from Philadelphia International on Tue, 1 Dec, arriving in St Louis.Inbound indirect flight with Delta, departs from St Louis on Fri, 1 Jan, arriving in Philadelphia International.Price includes taxes and charges.From $510, select.

St Louis.$513 per passenger.Departing Fri, 8 Jan, returning Fri, 22 Jan.Return flight with Southwest Airlines.Outbound direct flight with Southwest Airlines departs from Philadelphia International on Fri, 8 Jan, arriving in St Louis.Inbound direct flight with Southwest Airlines departs from St Louis on Fri, 22 Jan, arriving in Philadelphia International.Price includes taxes and charges.From $513, select.

St Louis.$513 per passenger.Departing Fri, 11 Dec, returning Fri, 25 Dec.Return flight with Southwest Airlines.Outbound direct flight with Southwest Airlines departs from Philadelphia International on Fri, 11 Dec, arriving in St Louis.Inbound direct flight with Southwest Airlines departs from St Louis on Fri, 25 Dec, arriving in Philadelphia International.Price includes taxes and charges.From $513, select.

St Louis.$515 per passenger.Departing Fri, 25 Sep, returning Mon, 28 Sep.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Philadelphia International on Fri, 25 Sep, arriving in St Louis.Inbound indirect flight with Frontier Airlines, departs from St Louis on Mon, 28 Sep, arriving in Philadelphia International.Price includes taxes and charges.From $515, select.

St Louis.$604 per passenger.Departing Tue, 1 Dec, returning Fri, 1 Jan.Return flight with Southwest Airlines.Outbound direct flight with Southwest Airlines departs from Philadelphia International on Tue, 1 Dec, arriving in St Louis.Inbound direct flight with Southwest Airlines departs from St Louis on Fri, 1 Jan, arriving in Philadelphia International.Price includes taxes and charges.From $604, select.

Find the cheapest month to fly from Philadelphia International to St Louis

We’re always keeping an eye on fares, so you can find the best one in seconds. It looks like Philadelphia International to St Louis flights are currently cheapest in October.

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Direct flights from Philadelphia International to St Louis

Philadelphia International to St Louis: Alternative routes

Compare routes from Philadelphia International to St Louis below. You may find an airport to fly into that's cheaper, faster, or easier than St Louis.

St Louis

20km from central St Louis

ClosestCheapest

from $153

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Belleville

32km from central St Louis

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Philadelphia to St Louis: Flight information

The things to know before you go.

Cheapest flight found	$153
Cheapest month to fly	October
Average flight time	2 hrs, 40 mins
Most popular airline	American Airlines
Average flights per week	77

Finding cheap flights from Philadelphia International to St Louis: Frequently asked questions

How much are return flights from Philadelphia International to St Louis?

The best price we found for a return flight from Philadelphia International to St Louis is $153. This is an estimate based on information collected from different airlines and travel providers over the last 4 days and is subject to change and availability.

How long does it take to fly from Philadelphia International to St Louis?

2 hours and 40 minutes is the average flight time from Philadelphia International to St Louis.

Which airlines fly direct from Philadelphia International to St Louis?

American Airlines, Southwest Airlines and Qatar Airways fly direct from Philadelphia International to St Louis.

How many flights are there a week from Philadelphia International to St Louis?

As of September 2026, there are 77 flights per week flying from Philadelphia International to St Louis.

When is the cheapest time to fly from Philadelphia International to St Louis?

The cheapest month to fly from Philadelphia International to St Louis is usually October.

Which upcoming date is cheapest to fly from Philadelphia International Airport to St Louis Airport on?

After crunching the numbers on our flight calendar, we found that it's currently cheapest to fly from Philadelphia International Airport to St Louis Airport on Wednesday, 14 October 2026.

Can I get a direct flight from Philadelphia International Airport to St Louis Airport?

Yes – the average flight time is 2 hours and 40 minutes.

How can I find the best flight deal to St Louis?

We show every price from over 1,200 airlines and travel agents, comparing them all so you don’t have to. If you know you want to fly to St Louis but you’re not ready to book, set up a Price Alert. We’ll track prices for you, and let you know when they rise or fall.

When is the best time to book flights to St Louis?

We crunched all the numbers in our flight calendar and it looks like the cheapest time to book a flight to St Louis is around 40 days in advance, so don’t leave your flight to the last minute.

Which is the cheapest airline to fly from Philadelphia International Airport to St Louis with?

Currently, Frontier Airlines and Southwest Airlines offer the cheapest flight tickets to St Louis.

Travelling from Philadelphia International Airport (PHL) to St Louis Airport (STL): what you need to know

Around 2 hours 35 minutes is how long you'll be travelling on a direct flight from Philadelphia International Airport to St Louis Airport.
St Louis is one hour behind Philadelphia and observes the UTC-6 timezone.
Each week, there are 26 Philadelphia International Airport to St Louis Airport flights. To take off as early as possible, jump on the 06:45 Southwest Airlines flight. If you'd rather make the most of your day before flying, the last departure is at 20:35 with Southwest Airlines.
Arriving two hours before an international flight and one hour ahead of a domestic departure are travel rules to live by. Get to the airport on time to catch your PHL to STL flight.
Flying during a peak time such as August? Public holidays and other popular seasons can mean longer queues at check-in and security. Be extra cautious and arrive up to four hours before international flights and two hours before a domestic departure.
American Airlines is your gateway to discovering St Louis (and perhaps some other exciting parts of the United States!). Browse the direct flights from Philadelphia International Airport to St Louis Airport offered by this popular carrier.
The airline that tops the list for bookings on this route is American Airlines.
The most punctual carrier that operates PHL to STL flights is Southwest Airlines. Its services land as scheduled 78.16% of the time.
If you want to explore another city along the way, simply deselect 'Direct flights only' when searching for your ticket from Philadelphia International Airport to St Louis Airport. Here are the most popular stopovers between PHL and STL:
- Washington Ronald Reagan Airport
- Washington Dulles Airport
- Nashville Airport

How to find the cheapest flights from Philadelphia International Airport (PHL) to St Louis Airport (STL)

Currently, $72 is the cheapest price we've seen for a one-way Philadelphia International Airport to St Louis Airport flight. The best price for a return plane ticket is $153. Keep in mind that fares can change due to demand when booking.
It's usually best to book as early as possible if you're hoping to get cheap tickets from PHL to STL. That's because airlines change prices based on demand, which tends to increase closer to the date of departure.
The cheapest month for flights from Philadelphia International Airport to St Louis Airport is May. Use the 'Whole month' tool to see the lowest airfares if you have a flexible schedule.
Picking up cheap flights from PHL to STL is a breeze with Price Alerts. All you need to do is create one of these automatic alerts and we'll get in touch as soon as a new deal comes up.
Pick your ideal departure and arrival times, number of stops and airlines with the filters. Alternatively, sort your results by 'Cheapest' to get the best deals on flights from Philadelphia International Airport to St Louis Airport.

Handy information about Philadelphia International Airport (PHL)

PHL's address is 8500 Essington Ave.
Of all flights leaving Philadelphia International Airport, 77% arrive as scheduled at their destination.
Central Philadelphia to Philadelphia International Airport is approximately 18 kilometres. Depending on traffic, it'll take you about 20 minutes to get there if you're driving, ride-sharing or catching a taxi.
You can expect a trip time of roughly 30 minutes on public transport.
Looking for a convenient hotel near PHL? If you're catching an early flight from Philadelphia International Airport to St Louis Airport, these accommodation options will put you moments from your check-in counter:

Arriving at St Louis Airport (STL)

Consider staying in a hotel near STL if you're taking a late Philadelphia International Airport to St Louis Airport flight. Select one of these options and make your arrival easier:
Pick up a St Louis Airport rental car and explore St Louis and beyond with your own set of wheels. Hertz, Budget and Alamo are top outlets you can book with here.
Booking your ride from St Louis Airport around one week ahead increases your chances of getting a good deal.

When to fly to St Louis Airport (STL)

July is the busiest month for flights from Philadelphia International Airport to St Louis Airport. To escape the crowds, head to St Louis in March.
When reserving your flight from Philadelphia International Airport to St Louis Airport, think about the kind of weather you enjoy. July is the warmest month in St Louis, with temperatures ranging from 17ºC to 33ºC.
Search for cheap tickets from PHL to STL in January if you'd rather travel during cooler conditions. Temperatures are at their lowest then, ranging between -7ºC and 8ºC on average.

Explore more of the United States

St Louis is easy to fall in love with, but there are so many other parts of the United States just waiting to be discovered. Around 418 kilometres north-east of St Louis, a visit to Chicago will keep your itinerary busy. Check out popular attractions like Millennium Park, Art Institute of Chicago and Willis Tower.
Indianapolis is another favourite destination in the United States and is around 370 kilometres east of St Louis. No trip is complete without experiencing Lucas Oil Stadium, Eiteljorg Museum and The Children's Museum of Indianapolis.