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$574+ Cheap flights from St. Louis (STL) to Porto (OPO)

This is the cheapest round-trip flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 3/10. Fares are subject to change and may not be available on all flights or dates of travel.
STL — OPO
Dec 13 — Dec 201
Sat 12/13
Sat 12/20
1 adult, Economy
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Cheap flight deals from St. Louis to Porto

Discover tips and strategies to find the most affordable flight options for your journey from St. Louis (STL) to Porto (OPO). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated November 13, 2025.

Most accurate provider

eDreams
3 stars

Most trusted provider

eDreams
3 stars

Round-trip from

$574
(United Airlines)

Popular in

July

Cheapest in

November

Average price

$612
Provider with most accurate pricing for Lambert-St Louis-Porto flight deals.
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Provider most trusted by Cheapflights users for Lambert-St Louis-Porto flights.
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From Lambert-St Louis to Porto
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Highest demand for flights based on searches. 18% potential increase in price ($238 potential increase over avg. RT price).
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Cheapest flight prices on average. 3% potential price decrease ($34 potential savings vs. average RT price).
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Average for round-trip flights in November 2025
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Find flight deals from St. Louis to Porto

Cheapest flights from St. Louis to Porto
Explore the most affordable flight options available from St. Louis to Porto. Find the lowest fares from popular airlines and budget airlines, with prices last updated on November 13, 2025.

This United Airlines deal was found by Cheapflights users on 11/11. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/277:00 amSTL - OPO
1 stop20h 30mUnited Airlines
Wed 12/106:00 amOPO - STL
1 stop13h 55mUnited Airlines
Deal found 11/11$669
This KLM deal was found by Cheapflights users on 11/12. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure KLM is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/122:38 pmSTL - OPO
2 stops13h 52mKLM
Tue 12/169:55 amOPO - STL
2 stops16h 52mKLM
Deal found 11/12$876
This Mytrip deal was found by Cheapflights users on 11/12. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/124:05 pmSTL - OPO
3 stops34h 05mMultiple Airlines
Tue 12/1612:40 pmOPO - STL
3 stops29h 35mMultiple Airlines
Deal found 11/12$1,226
This Mytrip deal was found by Cheapflights users on 11/11. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/274:05 pmSTL - OPO
3 stops19h 55mMultiple Airlines
Wed 12/106:35 pmOPO - STL
2 stops25h 17mMultiple Airlines
Deal found 11/11$1,345
This Travelocity deal was found by Cheapflights users on 11/12. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Travelocity is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/126:42 pmSTL - OPO
2 stops22h 58mLufthansa
Tue 12/164:15 pmOPO - STL
1 stop27h 40mLufthansa
Deal found 11/12$1,388
This Ovago deal was found by Cheapflights users on 11/11. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Ovago is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/296:35 pmSTL - OPO
2 stops36h 15mMultiple Airlines
Sat 1/38:40 amOPO - STL
2 stops19h 03mMultiple Airlines
Deal found 11/11$1,935
This Ovago deal was found by Cheapflights users on 11/12. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Ovago is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/2511:43 amSTL - OPO
2 stops13h 57mMultiple Airlines
Sat 1/37:50 pmOPO - STL
2 stops31h 21mMultiple Airlines
Deal found 11/12$2,159

Cheapflights Fare Finder

 
Customize your flight search to find flights from St. Louis to Porto that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated November 13, 2025.
Use the filters below to find and compare flights from St. Louis to Porto that are best for you.

Fly from

St. Louis

Fly to

Porto

Route

Depart

Return

Price

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Tue 3/10

5:40 pm-9:30 am

1 stop10h 50m

Porto

Wed 3/18

6:00 am-2:55 pm

1 stop13h 55m

$574

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Thu 11/27

7:00 am-9:30 am

1 stop20h 30m

Porto

Wed 12/10

6:00 am-1:55 pm

1 stop13h 55m

$669

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Fri 3/27

11:25 am-9:30 am

2 stops17h 05m

Porto

Tue 3/31

6:00 am-10:59 pm

2 stops22h 59m

$867

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Fri 12/12

2:38 pm-10:30 am

2 stops13h 52m

Porto

Tue 12/16

9:55 am-8:47 pm

2 stops16h 52m

$876

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Fri 3/27

4:50 pm-2:45 pm

1 stop16h 55m

Porto

Tue 3/31

6:00 am-9:03 pm

2 stops21h 03m

$878

Flights are sorted by cheapest round-trip flights first.

Deals found on 11/11

Compare providers for flights from St. Louis to Porto

Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.
Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from St. Louis to Porto in November.
ProviderPrice AccuracyTrust Score*
FlightHubPrice Accuracy3 starsTrust Score*1 star
eDreamsPrice Accuracy3 starsTrust Score*3 stars

*The Trust Score is based on feedback from users after their booking experience. It measures overall satisfaction, helping us identify issues like hidden fees, problems during the ticketing process, and the quality of customer service. This score is our best indicator of the provider's quality and reliability.

  • Most accurate provider: When it comes to deals on St. Louis-Porto flights, users find the pricing of eDreams to be most consistent on Cheapflights vs. eDreams Users can find the same prices on St. Louis-Porto flight deals on Cheapflights vs. eDreams >95% of the time. Price accuracy is based on data collected from St. Louis-Porto flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on St. Louis-Porto flights, Cheapflights users trust eDreams the most. eDreams has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for St. Louis-Porto flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.

Best time to book a flight from St. Louis to Porto

Have a flexible travel schedule? Discover the best time to fly to Porto from St. Louis with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from St. Louis to Porto

What is the cheapest time of day to fly from STL to OPO?

Find hourly flight availability from St. Louis to Porto. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated November 13, 2025.

Unlike in the evening, when flights are generally more expensive, you can save up to 39% on flights from St. Louis to Porto by exploring options for tickets at noon.

How much does it cost to fly round-trip from St. Louis to Porto?

Reviews of airlines servicing Porto

Get insights into the airlines that provide service to Porto. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Porto. Reviews last updated November 13, 2025.
Read reviews from past customers who have flown United Airlines and Lufthansa from St. Louis to Porto. Users can see the overall rating for each airline as well as how each is rated in terms of entertainment options, comfort, food, crew/service, and boarding process.
United Airlines
7.4
Good
9,017 reviews

Food

6.6

Overall

7.4

Comfort

7.3

Crew

8.1

Entertainment

7.1

Boarding

7.7

Reviews

1 / 20
2.0
Mediocre

Sebrena,Oct 2025

IAH - RSW

The worst that I have ever experienced in my life so bad if it was free I'm not ever going to use your Airline again I dont believe ..... very disappointed 😞 😔0000000000000
United Airlines
7.4
Good
9,017 reviews
United Airlines
7.4
Good
9,017 reviews

Food

6.6

Overall

7.4

Comfort

7.3

Crew

8.1

Entertainment

7.1

Boarding

7.7

Reviews

1 / 20
2.0
Mediocre

Sebrena,Oct 2025

IAH - RSW

The worst that I have ever experienced in my life so bad if it was free I'm not ever going to use your Airline again I dont believe ..... very disappointed 😞 😔0000000000000
Lufthansa
6.8
Okay
7,572 reviews
United Airlines
7.4
Good
9,017 reviews

Food

6.6

Overall

7.4

Comfort

7.3

Crew

8.1

Entertainment

7.1

Boarding

7.7

Reviews

1 / 20
2.0
Mediocre

Sebrena,Oct 2025

IAH - RSW

The worst that I have ever experienced in my life so bad if it was free I'm not ever going to use your Airline again I dont believe ..... very disappointed 😞 😔0000000000000

Related info for your journey

Find useful and relevant information for your journey from St. Louis to Porto. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • How long is the flight from St. Louis to Porto?

    There are many flights that can get you from St. Louis to Porto in 10h 50m. Fly via United Airlines to get the fastest option. Airlines will cover a distance of 4154 mi.

  • What are the cheapest airlines flying from St. Louis to Porto round-trip?

    Lufthansa, at $549, was found to be the cheapest airline from St. Louis to Porto. An alternate airline flying to your destination would be United Airlines. Users have found that Lufthansa is 47% cheaper than the other options available to this destination.

  • Can I find deals for flights from St. Louis to Porto that include hotel bookings?

    Yes. In addition to deals on St. Louis to Porto flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from St. Louis to Porto?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from St. Louis to Porto.

  • Can I find deals for business class flights from St. Louis to Porto?

    Yes. Cheapflights offers flight deals from St. Louis to Porto by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

See more FAQs

Traveling to a place near Porto?

Book flights to Porto if you plan to visit one of these locations
Aveiro
Arcos de Valdevez
Coimbra
Vila Nova de Gaia

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Alternative routes for St. Louis to Porto

See prices for flight routes from nearby airports that may be better suited for you.
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Top 2 airlines flying from St. Louis to Porto

Discover the top 2 airlines that operate flights from St. Louis to Porto. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated November 13, 2025.
AirlineCheapestAverageFlexibilityOn-time
LufthansaCheapest$549Average$1,214FlexibilityNo cancel feeOn-time76%
United AirlinesCheapest$751Average$1,177FlexibilityNo cancel feeOn-time69%

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