Cheap Flights from St. Louis (CPS) to Philadelphia (PHL)

Popular airlines from St. Louis, MO (CPS-St. Louis Downtown) to Philadelphia Intl. Airport (PHL)

Flights from St. Louis (CPS) to Philadelphia (PHL)
Origin airport
St. Louis Downtown
Destination airport
Philadelphia Intl.
Distance
802 mi

St. Louis to Philadelphia Flights

The cheapest times to fly from St. Louis to Philadelphia

On average, Thursday can be the cheapest time to fly, according to data from the Airlines Reporting Corporation (ARC), one of the world's biggest databases for global airline sales. The data reveals that you could save up to 16% by flying on a Thursday—the cheapest day to travel on average—instead of a Sunday—the most expensive. Some of the most affordable flights from St. Louis to Philadelphia are during the month of . You can find some of the cheapest flights from St. Louis to Philadelphia with Expedia's search tool and vast selection of airlines.

 

The best time to book a flight from St. Louis to Philadelphia

Sunday is one of the best days to book for cheap flights from St. Louis to Philadelphia: Tickets reserved on a Sunday cost between 6% and 13% less than those reserved on a Friday, according to ARC data. The data also suggests booking early can also lead to cheaper airfares. You could save 24% by buying your tickets for domestic flights at least a month in advance and 10% by booking international flights 2 months in advance.

 

How to find cheap round-trip tickets from St. Louis to Philadelphia

Being flexible with your dates and using Expedia's Price Drop Protection and Price Tracking features are some of the best ways of finding a cheap ticket from St. Louis to Philadelphia in 2025. You can also book with separate airlines for your outbound and return journeys, from one-way. Expedia also offers Price Drop Protection, so if the cost of your airfare goes down after booking, you'll receive a credit for the difference*. This is available for a small fee, and is free to One Key Gold and Platinum tier members.

 

Expedia's Price Tracking feature means you can stay on top of airfares without manually checking every day. It sends you automated price alerts for cheap St. Louis to Philadelphia flights and uses historical data to indicate when the best time to book is. Download Expedia's free app to activate this handy tool in a few easy taps.

 

You could also save big by booking one of Expedia's vacation packages. Bundling together your St. Louis to Philadelphia airfare with your accommodations and car rental is often cheaper than booking everything separately. There’s also One Key, Expedia's generous rewards program. Join for free and you could earn One Key cash on most bookings to save on future adventures.

 

*Terms apply.

 

Disclaimer: ARC The statistics are based on average round-trip ticket prices between January and August 2023. The percentages you see are averages.

 

Frequently asked questions

How much does a flight from St. Louis Downtown Airport (CPS) to Philadelphia Intl. Airport (PHL) cost?
Snag a cheap one-way flight or cheap return flight from St. Louis Downtown Airport (CPS) to Philadelphia Intl. Airport (PHL) with Expedia. Enter your travel dates and sort by "Price (lowest to highest)" to find our cheapest flight deals on this route.
What is the cheapest month to fly from St. Louis Downtown Airport (CPS) to Philadelphia Intl. Airport (PHL)?
The cheapest month to fly from CPS to PHL is , when there's less demand. Off-peak months are often when better flight deals are available between these airports.
Which airlines fly direct from St. Louis Downtown Airport (CPS) to Philadelphia Intl. Airport (PHL)?
Although St. Louis, MO (CPS-St. Louis Downtown) has no direct flights to Philadelphia Intl. Airport (PHL), other airports have nonstop options. Traveling from Lambert-St. Louis Intl. Airport (STL) will get you to Philadelphia without any detours.
What is the cheapest airline that flies from St. Louis Downtown Airport (CPS) to Philadelphia Intl. Airport (PHL)?
To find the cheapest airline flying from CPS to PHL, use Expedia's filter tool. Customize your search based on your travel style, such as preferred carriers and ideal departure window. You can then sort your results by "Price (lowest to highest)" to see the most affordable options first.
How many flights per day from St. Louis Downtown Airport (CPS) to Philadelphia Intl. Airport (PHL)?
You'll need to take a flight with a layover when traveling from St. Louis Downtown Airport (CPS) to Philadelphia Intl. Airport (PHL). Direct flights don't operate daily on this route. However, just filter your search to include one or two stops to discover an option that works for you.
What day of the week has the most flights from CPS to PHL?
Generally you'll find the largest variety of flight choices on a Friday. Tuesdays tend to be the quietest.* However, this can vary depending on the airline, season and other factors.*Busiest/quietest day to travel is based on Expedia flight demand through January to December 2024.
What is the best time to fly from St. Louis Downtown Airport (CPS) to Philadelphia Intl. Airport (PHL)?
To arrive at Philadelphia Intl. Airport (PHL) on time, pick a flight that takes off from St. Louis Downtown Airport (CPS) before 3 PM. The likelihood of cancellations is 22% higher, on average, for departures after this time.**Most reliable time of the day and month to travel recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.
Is it cheaper to buy a plane ticket from St. Louis Downtown Airport (CPS) to Philadelphia Intl. Airport (PHL) last-minute?
Last-minute bookings from CPS to PHL are generally more expensive. To secure the lowest prices, start looking for flights as early as possible. That being said, if you're flexible with your travel plans, you may score a cheap fare right before your trip.
Is it cheaper to book a CPS to PHL flight and hotel package?
You'll generally save money by securing a CPS to PHL flight and hotel package compared to booking separately. In fact, travelers could save hundreds of dollars by bundling with Expedia. And it's simple to manage everything in one convenient place. Once you've chosen your ideal flights and accommodations, consider other add-ons like car rentals, activities and tours.
Can I cancel or change the date of my flight from St. Louis Downtown Airport (CPS) to Philadelphia Intl. Airport (PHL)?
Typically, you can modify or cancel your CPS to PHL flight. However, additional charges may apply, especially if you booked more than 24 hours ago. Double-check your itinerary for the airline's fees and policies on flight changes, or if you need further details, go to our Customer Service portal.

Explore a world of travel with Expedia

*Available to One Key members.