$104 Cheap Flights from Trenton (TTN) to St. Louis (STL)

View $104 flight on Tue, Aug 12, 2025Opens in a new window

Popular airlines from Trenton–Mercer Airport (TTN) to St. Louis Lambert Intl. Airport (STL)

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Cheap Flights from Trenton to St. Louis (TTN-STL)

Prices were available within the past 7 days and start at $104 for one-way flights and $208 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Frontier Airlines
Tue, Aug 12 - Wed, Aug 13
TTN
Trenton
STL
St. Louis
$208 Roundtrip, found 19 hours ago
$208
Roundtrip
found 19 hours ago
Select Frontier Airlines flight, departing Tue, Aug 12 from Trenton to St. Louis, returning Wed, Aug 13, priced at $208 found 19 hours ago
Frontier Airlines
Tue, Aug 12 - Fri, Aug 22
TTN
Trenton
STL
St. Louis
$218 Roundtrip, just found
$218
Roundtrip
just found
Select Frontier Airlines flight, departing Tue, Aug 12 from Trenton to St. Louis, returning Fri, Aug 22, priced at $218 just found
Frontier Airlines
Thu, Aug 21 - Sun, Aug 31
TTN
Trenton
STL
St. Louis
$228 Roundtrip, just found
$228
Roundtrip
just found
Select Frontier Airlines flight, departing Thu, Aug 21 from Trenton to St. Louis, returning Sun, Aug 31, priced at $228 just found
Frontier Airlines
Tue, Aug 12 - Mon, Aug 25
TTN
Trenton
STL
St. Louis
$248 Roundtrip, found 14 hours ago
$248
Roundtrip
found 14 hours ago
Select Frontier Airlines flight, departing Tue, Aug 12 from Trenton to St. Louis, returning Mon, Aug 25, priced at $248 found 14 hours ago
Frontier Airlines
Fri, Aug 22 - Sun, Aug 31
TTN
Trenton
STL
St. Louis
$258 Roundtrip, just found
$258
Roundtrip
just found
Select Frontier Airlines flight, departing Fri, Aug 22 from Trenton to St. Louis, returning Sun, Aug 31, priced at $258 just found
Frontier Airlines
Fri, Aug 22 - Sun, Aug 24
TTN
Trenton
STL
St. Louis
$288 Roundtrip, found 1 hour ago
$288
Roundtrip
found 1 hour ago
Select Frontier Airlines flight, departing Fri, Aug 22 from Trenton to St. Louis, returning Sun, Aug 24, priced at $288 found 1 hour ago
Frontier Airlines
Sat, Aug 16 - Mon, Sep 1
TTN
Trenton
STL
St. Louis
$298 Roundtrip, found 14 hours ago
$298
Roundtrip
found 14 hours ago
Select Frontier Airlines flight, departing Sat, Aug 16 from Trenton to St. Louis, returning Mon, Sep 1, priced at $298 found 14 hours ago
Frontier Airlines
Sun, Oct 5 - Thu, Oct 9
TTN
Trenton
STL
St. Louis
$306 Roundtrip, found 2 days ago
$306
Roundtrip
found 2 days ago
Select Frontier Airlines flight, departing Sun, Oct 5 from Trenton to St. Louis, returning Thu, Oct 9, priced at $306 found 2 days ago
Frontier Airlines
Thu, Aug 28 - Mon, Sep 1
TTN
Trenton
STL
St. Louis
$308 Roundtrip, found 2 hours ago
$308
Roundtrip
found 2 hours ago
Select Frontier Airlines flight, departing Thu, Aug 28 from Trenton to St. Louis, returning Mon, Sep 1, priced at $308 found 2 hours ago
American Airlines
Wed, Oct 22 - Sat, Oct 25
TTN
Trenton
STL
St. Louis
$315 Roundtrip, found 17 hours ago
$315
Roundtrip
found 17 hours ago
Select American Airlines flight, departing Wed, Oct 22 from Trenton to St. Louis, returning Sat, Oct 25, priced at $315 found 17 hours ago

Alternative airports near St. Louis

Prices were available within the past 7 days. Prices and availability are subject to change.

Select flight to Lambert-St. Louis Intl. STL. Cheapest option available. Average driving time to city center is 20 minutes. Flights from $218
STL
Lambert-St. Louis Intl.
Cheapest
Average driving time to city center20 min
Flights from $218
Flights from Trenton (TTN) to St. Louis (STL)
Origin airport
Mercer
Destination airport
Lambert-St. Louis Intl.
Airlines serving
American Airlines, Frontier Airlines
Roundtrip price
$208
Distance
834 mi

Trenton to St. Louis Flights

The cheapest times to fly from Trenton to St. Louis

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 Trenton to St. Louis are during the month of August. You can find some of the cheapest flights from Trenton to St. Louis with Expedia's search tool and vast selection of airlines.

 

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

Sunday is one of the best days to book for cheap flights from Trenton to St. Louis: 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 Trenton to St. Louis

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 Trenton to St. Louis in 2025. You can also book with separate airlines for your outbound and return journeys, from $104 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 Trenton to St. Louis 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 Trenton to St. Louis 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 Mercer Airport (TTN) to Lambert-St. Louis Intl. Airport (STL) cost?
Discover the latest flight deals from TTN to STL by entering your preferred travel dates and searching on Expedia. Easily compare prices by departure date if you have flexibility with your schedule and use handy filters to explore prices for your preferred journey. As a member of One Key™, our free loyalty program, you can use Price Tracking to watch fares and receive notifications if prices go up or down.
What is the cheapest month to fly from TTN to STL?
The cheapest flights from TTN to STL are usually during off-peak season, when demand is lower. To save money, avoid flying during public holidays, school breaks and major local events.
Which airlines fly direct from Mercer Airport (TTN) to Lambert-St. Louis Intl. Airport (STL)?
While Trenton, NJ (TTN-Mercer) doesn't offer any direct flights to Lambert-St. Louis Intl. Airport (STL), other airports have nonstop options. Departing from Liberty Intl. Airport (EWR) will get you to St. Louis without any layovers.
What is the cheapest airline that flies from TTN to STL?
Use the filter tool on Expedia to compare airlines and find the cheapest carrier that'll take you from TTN to STL. Sort your results by "Price (lowest to highest)" to snap up a great deal.
How many flights per day from Mercer Airport (TTN) to Lambert-St. Louis Intl. Airport (STL)?
You'll need to book a flight with a layover when traveling from Mercer Airport (TTN) to Lambert-St. Louis Intl. Airport (STL). There are no daily direct flights on this route. However, simply filter your search to include one or two stops to discover the best option for your trip.
What day of the week has the most flights from TTN to STL?
Usually you'll have the most choice when it comes to flights on a Friday. Tuesdays tend to be the quietest.* But 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 Mercer Airport (TTN) to Lambert-St. Louis Intl. Airport (STL)?
Select a flight from Mercer Airport (TTN) to Lambert-St. Louis Intl. Airport (STL) that leaves before 3 PM to reduce the likelihood of delays. Departures after this time are on average 22% more likely to be canceled.**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 Mercer Airport (TTN) to Lambert-St. Louis Intl. Airport (STL) last-minute?
Booking your plane ticket from TTN to STL just before your getaway is usually more expensive. But if you're flexible with your schedule, you could score a cheap last-minute fare.
Is it cheaper to book a TTN to STL flight and hotel package?
You'll generally save money by booking a TTN to STL 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 it all in one place. After choosing your preferred accommodations and flights, you can add extras like car rentals, tours and activities.
Can I cancel or change the date of my flight from Mercer Airport (TTN) to Lambert-St. Louis Intl. Airport (STL)?
In most cases, you can reschedule or cancel your TTN to STL flight. However, there may be additional charges, especially if you booked over 24 hours ago. Check your itinerary for the airline's fees and guidelines on flight changes, or if you need more details, visit our Customer Service portal.

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Trenton nearby Airports

Newark Liberty Intl. Airport

Newark Liberty Intl. Airport to St. Louis
$138.76

Philadelphia

Lehigh Valley Intl. to St. Louis
$148.76

Trenton

Mercer to St. Louis
$207.98

Allentown

Lehigh Valley Intl. to St. Louis
$236.36
*Available to One Key members.