$405 Cheap Flights from St. Louis (STL) to Porto (OPO)

View $405 flight on Fri, Nov 28, 2025Opens in a new window

Popular airlines from St. Louis Lambert Intl. Airport (STL) to Porto Airport (OPO)

Cheap Flights from St. Louis to Porto (STL-OPO)

Prices were available within the past 7 days and start at $405 for one-way flights and $480 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Lufthansa
Fri, Nov 28 - Fri, Dec 5
STL
St. Louis
OPO
Porto
$480 Roundtrip, found 1 day ago
$480
Roundtrip
found 1 day ago
Select Lufthansa flight, departing Fri, Nov 28 from St. Louis to Porto, returning Fri, Dec 5, priced at $480 found 1 day ago
United
Fri, Nov 28 - Thu, Dec 4
STL
St. Louis
OPO
Porto
$484 Roundtrip, found 4 hours ago
$484
Roundtrip
found 4 hours ago
Select United flight, departing Fri, Nov 28 from St. Louis to Porto, returning Thu, Dec 4, priced at $484 found 4 hours ago
Lufthansa
Fri, Nov 28 - Fri, Dec 5
STL
St. Louis
OPO
Porto
$489 Roundtrip, found 1 day ago
$489
Roundtrip
found 1 day ago
Select Lufthansa flight, departing Fri, Nov 28 from St. Louis to Porto, returning Fri, Dec 5, priced at $489 found 1 day ago
Lufthansa
Fri, Nov 28 - Fri, Dec 5
STL
St. Louis
OPO
Porto
$490 Roundtrip, found 1 day ago
$490
Roundtrip
found 1 day ago
Select Lufthansa flight, departing Fri, Nov 28 from St. Louis to Porto, returning Fri, Dec 5, priced at $490 found 1 day ago
United
Fri, Nov 28 - Tue, Dec 2
STL
St. Louis
OPO
Porto
$493 Roundtrip, found 4 hours ago
$493
Roundtrip
found 4 hours ago
Select United flight, departing Fri, Nov 28 from St. Louis to Porto, returning Tue, Dec 2, priced at $493 found 4 hours ago
Delta
Fri, Nov 28 - Wed, Dec 3
STL
St. Louis
OPO
Porto
$498 Roundtrip, found 4 hours ago
$498
Roundtrip
found 4 hours ago
Select Delta flight, departing Fri, Nov 28 from St. Louis to Porto, returning Wed, Dec 3, priced at $498 found 4 hours ago
Lufthansa
Fri, Nov 28 - Fri, Dec 5
STL
St. Louis
OPO
Porto
$499 Roundtrip, found 1 day ago
$499
Roundtrip
found 1 day ago
Select Lufthansa flight, departing Fri, Nov 28 from St. Louis to Porto, returning Fri, Dec 5, priced at $499 found 1 day ago
British Airways
Sat, Feb 14 - Sat, Feb 21
STL
St. Louis
OPO
Porto
$501 Roundtrip, found 1 day ago
$501
Roundtrip
found 1 day ago
Select British Airways flight, departing Sat, Feb 14 from St. Louis to Porto, returning Sat, Feb 21, priced at $501 found 1 day ago
Lufthansa
Mon, Dec 1 - Wed, Dec 10
STL
St. Louis
OPO
Porto
$503 Roundtrip, found 14 hours ago
$503
Roundtrip
found 14 hours ago
Select Lufthansa flight, departing Mon, Dec 1 from St. Louis to Porto, returning Wed, Dec 10, priced at $503 found 14 hours ago
Air Canada
Wed, Feb 4 - Wed, Feb 11
STL
St. Louis
OPO
Porto
$551 Roundtrip, found 2 days ago
$551
Roundtrip
found 2 days ago
Select Air Canada flight, departing Wed, Feb 4 from St. Louis to Porto, returning Wed, Feb 11, priced at $551 found 2 days ago

Alternative airports near Porto

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

Select flight to Dr. Francisco de Sa Carneiro OPO. Cheapest and Closest option available. Average driving time to city center is 14 minutes. Flights from $723
OPO
Dr. Francisco de Sa Carneiro
CheapestClosest
Average driving time to city center14 min
Flights from $723

Frequently asked questions

How much does a flight from Lambert-St. Louis Intl. Airport (STL) to Dr. Francisco de Sa Carneiro Airport (OPO) cost?
Get a cheap one-way flight from $405 or cheap return flight from $480 from Lambert-St. Louis Intl. Airport (STL) to Dr. Francisco de Sa Carneiro Airport (OPO) with Expedia. Enter your travel dates and sort by "Price (lowest to highest)" to find our cheapest flight offers on this route.
What is the cheapest month to fly from Lambert-St. Louis Intl. Airport (STL) to Dr. Francisco de Sa Carneiro Airport (OPO)?
Flying in November is a great way to save, as it's the cheapest month for flights between STL and OPO. You'll typically find the lowest fares during the off-season.
What is the cheapest airline that flies from Lambert-St. Louis Intl. Airport (STL) to Dr. Francisco de Sa Carneiro Airport (OPO)?
Expedia's filter tool lets you easily compare different airlines, travel time and fares all in one place. Tailor the search to your trip, then sort by "Price (lowest to highest)" to find the carrier with the cheapest STL to OPO flight.
How many flights per day from Lambert-St. Louis Intl. Airport (STL) to Dr. Francisco de Sa Carneiro Airport (OPO)?
You'll have to catch a flight with a layover when traveling from Lambert-St. Louis Intl. Airport (STL) to Dr. Francisco de Sa Carneiro Airport (OPO). Direct flights don't operate daily on this route. However, simply filter your search to include one or more stops to find an option that works for you.
What day of the week has the most flights from STL to OPO?
You'll typically find Tuesday the quietest day for flights, while Fridays tend to be the busiest.* However this can vary from season to season and during peak travel times or public holidays.*Busiest/quietest day to travel is based on Expedia flight demand through January to December 2024.
What is the best time to fly from Lambert-St. Louis Intl. Airport (STL) to Dr. Francisco de Sa Carneiro Airport (OPO)?
To avoid potential delays on the Lambert-St. Louis Intl. Airport (STL) to Dr. Francisco de Sa Carneiro Airport (OPO) route, travel before 3 PM. Flights after this time have a 22% higher chance of cancellation.**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 Lambert-St. Louis Intl. Airport (STL) to Dr. Francisco de Sa Carneiro Airport (OPO) last-minute?
Waiting until right before your break to book a ticket from STL to OPO often results in higher prices. While you might find some last-minute deals, they aren't always guaranteed. Keep your travel plans flexible to maximize your chances of landing a bargain.
Is it cheaper to book a STL to OPO flight and hotel package?
Opting for a STL to OPO flight and hotel package is typically cheaper than booking separately. With Expedia, you can enjoy the ease of organizing your travels all in one place. Pick from our impressive range of hotels and then add activities, flights and car rentals to your booking. Bundle it all together, and you could save hundreds of dollars.
Can I cancel or change the date of my flight from Lambert-St. Louis Intl. Airport (STL) to Dr. Francisco de Sa Carneiro Airport (OPO)?
In most instances, you're able to cancel or reschedule your STL to OPO flight. However, additional charges may apply, especially if your booking was made over 24 hours ago. Double-check your itinerary for the airline's fees and guidelines on flight changes, or if you need further information, head to our Customer Service portal.

Travel information

Origin airport
Lambert-St. Louis Intl.
Destination airport
Dr. Francisco de Sa Carneiro
Airlines serving
Air Canada, Air France, American Airlines, British Airways, Brussels Airlines, Delta, Iberia, KLM, Lufthansa, Scandinavian Airlines, Turkish Airlines, United
Roundtrip price
$480
Distance
4158 mi

Book with confidence

St. Louis to Porto Flights

The cheapest times to fly from St. Louis to Porto

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

 

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

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

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 Porto in 2025. You can also book with separate airlines for your outbound and return journeys, from $405 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 Porto 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 Porto 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.

 

St. Louis to Porto Flights

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*Available to One Key members.