Cheap flights from St. Louis to Philadelphia from $66
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 9/7. 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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Fly from
Fly to
Route
Depart
Return
St. LouisPhiladelphia
STL Lambert-St Louis - PHL Philadelphia
STLPHL
Lambert-St Louis
Fri 10/9
10:35 am-7:36 am
1 stop20h 01m
Philadelphia
Mon 10/12
5:38 pm-9:40 am
1 stop17h 02m
St. LouisPhiladelphia
STL Lambert-St Louis - PHL Philadelphia
STLPHL
Lambert-St Louis
Fri 10/9
10:35 am-7:36 am
1 stop20h 01m
Philadelphia
Mon 10/12
5:57 pm-9:40 am
2 stops16h 43m
St. LouisPhiladelphia
STL Lambert-St Louis - PHL Philadelphia
STLPHL
Lambert-St Louis
Thu 9/3
6:17 pm-8:28 pm
1 stop25h 11m
Philadelphia
Tue 9/8
6:40 pm-1:10 pm
2 stops19h 30m
St. LouisPhiladelphia
STL Lambert-St Louis - PHL Philadelphia
STLPHL
Lambert-St Louis
Fri 9/11
10:05 am-5:25 pm
1 stop6h 20m
Philadelphia
Mon 9/14
6:20 am-7:35 am
Nonstop2h 15m
St. LouisPhiladelphia
STL Lambert-St Louis - PHL Philadelphia
STLPHL
Lambert-St Louis
Sat 9/12
10:15 am-1:25 pm
Nonstop2h 10m
Philadelphia
Tue 9/15
2:45 pm-4:05 pm
Nonstop2h 20m
St. LouisPhiladelphia
STL Lambert-St Louis - PHL Philadelphia
STLPHL
Lambert-St Louis
Wed 9/9
6:40 pm-9:55 pm
Nonstop2h 15m
Philadelphia
Wed 9/16
6:25 am-7:40 am
Nonstop2h 15m
St. LouisPhiladelphia
STL Lambert-St Louis - PHL Philadelphia
STLPHL
Lambert-St Louis
Thu 9/3
6:00 am-9:22 am
Nonstop2h 22m
Philadelphia
Sun 9/6
3:28 pm-5:01 pm
Nonstop2h 33m
St. LouisPhiladelphia
STL Lambert-St Louis - PHL Philadelphia
STLPHL
Lambert-St Louis
Thu 12/10
6:02 am-9:20 am
Nonstop2h 18m
Philadelphia
Mon 12/14
10:55 am-12:43 pm
Nonstop2h 48m
St. LouisPhiladelphia
STL Lambert-St Louis - PHL Philadelphia
STLPHL
Lambert-St Louis
Thu 10/1
6:54 pm-12:40 am
1 stop4h 46m
Philadelphia
Mon 10/5
7:20 pm-11:42 pm
1 stop5h 22m
St. LouisPhiladelphia
STL Lambert-St Louis - PHL Philadelphia
STLPHL
Lambert-St Louis
Sat 8/29
7:00 am-2:42 pm
1 stop6h 42m
Philadelphia
Tue 9/1
10:00 am-4:17 pm
1 stop7h 17m
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 typical price of a round-trip flight between St. Louis and Philadelphia?
Prices are currently low for flights on this route.
Typical prices usually range from $277 to $457.The lowest price recently found on this route was $160.
What is the cheapest month to fly to Philadelphia?
The cheapest month to fly to Philadelphia from St. Louis is in September. Flight prices, which tend to average around $337, are often lower during this time because this is during the off-season. The month of August is another great option to travel to Philadelphia, with average flight prices from St. Louis averaging around $368.
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 Friday. Travelers who choose to depart for Philadelphia on a Friday will often find tickets for as low as $533. On the other hand, Saturday 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 $801.
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 $443. 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 $904.
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 from St. Louis 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 $431 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 $356 on momondo.
What cabin class options are available on St. Louis to Philadelphia flights?
There are 4 cabin classes available to choose from on 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 3% 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 August 2026, prices for St. Louis to Philadelphia flights are approximately 132% more expensive when compared to flights at the same time last year.
What is the cheapest airline that flies from Lambert-St Louis to Philadelphia?
Frontier and Southwest are the most popular carriers operating from Lambert-St Louis to Philadelphia
What airlines fly to Philadelphia?
American Airlines, United Airlines and Delta are the top three most popular airlines that fly to Philadelphia from St. Louis according to our data. American Airlines is the first choice among our users, with 37% of people opting to fly with this airline when traveling to Philadelphia. Keep in mind that there are 5 different airlines that fly to Philadelphia on a routine basis, so you have a few additional options to choose from.
How many flights depart from St. Louis to Philadelphia on average per day?
As of August 2026, 9 flights take off from St. Louis and land in Philadelphia each day. The most common flight departure time for this route is 11:00AM, with 82% of daily flights taking off at noon.
How many flights depart from St. Louis to Philadelphia on average per week?
The number of flights available between St. Louis and Philadelphia is 63 per week as of August 2026. The most frequent departure day is Mon, with 16% of weekly flights leaving on this day.
When to book flights from St. Louis to Philadelphia
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
Frequently asked questions about flying from St. Louis to Philadelphia
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 05m, 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?
The number of operators available for flights from Lambert-St Louis Airport to Philadelphia Airport is 3 as of August 2026.
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?
Based on momondo bookings for flights between St. Louis and Philadelphia, the leading plane model is Airbus A319, making up 37.94% of the total bookings. Other popular models include Boeing 737 MAX 8 with 16.53%, Canadair (Bombardier) Regional Jet 900 with 13.01%, and Boeing 737-800 Passenger/BBJ2 (winglets) with 7.59%.
What is the most popular airline from St. Louis to Philadelphia?
momondo data reveals that the most frequently booked airline on the route from St. Louis to Philadelphia is American Airlines, representing 58% of all bookings. The subsequent popular airlines are Southwest at 29% and Frontier at 13%.
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 | ||
|---|---|---|---|---|---|
| PriceFrom $124 | Free Cancellation | Rating 5.6 2,710 reviews | |||
| PriceFrom $277 | Free Cancellation | Rating 7.1 11,899 reviews | |||
| PriceFrom $287 | Free Cancellation | Rating 8.0 4,218 reviews |
Southwest Flights From St. Louis to Philadelphia
Southwest flight deals from St. Louis to Philadelphia start from $287 round-trip. Over the 9 Southwest flights for this route in a normal week, average airfare is usually $466 round-trip - but some users have found much cheaper deals with momondo.
American Airlines Flights From St. Louis to Philadelphia
American Airlines (7.1/10 from 11,899 reviews) operates around 20 flights from St. Louis to Philadelphia in any given week. The average American Airlines airfare for this route is around $451, with deals from around $277 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 locationsWhy 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.