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

United Airlines, at $842, was found to be the cheapest airline from St. Louis to Porto.Alternate airlines to your destination round-trip include Delta and Lufthansa. Users have found that United Airlines is 13% cheaper than the other options available to this destination.

What is the cheapest day to fly from St. Louis to Porto?

Travelers seeking maximum savings on their St. Louis to Porto flight should consider departing on Tuesday afternoons when fares are most often at their lowest. Monday mornings flights should be avoided if possible as fares are typically the most expensive at this time.

What is the cheapest day to fly round-trip from St. Louis to Porto?

Users have found that leaving on a Wednesday can be a cost-effective option. It’s possible to save up to 94% on your flight compared to booking on days when demand is much higher.

What is the cheapest month to fly from St. Louis to Porto?

Flights from St. Louis to Porto lean towards being more expensive in June. Prices are generally better when you fly from St. Louis to Porto in November, with the cheapest ticket starting at $557.

Most accurate provider : When it comes to deals on St. Louis-Porto flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on St. Louis-Porto flight deals on Cheapflights vs. FlightHub >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 FlightHub the most. FlightHub 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.

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.

$643+ Flights from St. Louis to Porto

Home Search by date Vacation packages Hotels Flight deals Car rental Travel tips & news

Find cheap flights from St. Louis to Porto with Cheapflights

1. Tell us where you want to go

Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”

2. Select your favorite providers

We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.

3. Compare prices and book

Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.

Cheap flight deals from St. Louis to Porto

Most accurate provider	FlightHub 3 stars
Most trusted provider	FlightHub 3 stars
Round-trip from	$826 (Air France)
Popular in	June
Cheapest in	November
Average price	$946

Provider with most accurate pricing for Lambert-St Louis-Porto flight deals.

Search Deals

Provider most trusted by Cheapflights users for Lambert-St Louis-Porto flights.

Search Deals

From Lambert-St Louis to Porto

Search Deals

Highest demand for flights based on searches. 25% potential increase in price ($332 potential increase over avg. RT price).

Search Deals

Cheapest flight prices on average. 4% potential price decrease ($46 potential savings vs. average RT price).

Search Deals

Average for round-trip flights in March 2025

Search Deals

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 March 28, 2025.

Wed 10/226:15 amSTL - OPO

2 stops21h 30mUnited Airlines

Wed 11/56:00 amOPO - STL

2 stops20h 59mUnited Airlines

Deal found 3/27

$643

Sun 10/193:30 pmSTL - OPO

2 stops18h 00mDelta

Mon 11/311:15 amOPO - STL

2 stops36h 40mDelta

Deal found 3/27

$656

Sun 10/193:30 pmSTL - OPO

1 stop18h 10mLufthansa

Thu 11/64:30 pmOPO - STL

1 stop27h 25mLufthansa

Deal found 3/27

$665

Sun 10/194:05 pmSTL - OPO

2 stops20h 10mAir Canada

Sat 11/88:40 amOPO - STL

2 stops36h 46mAir Canada

Deal found 3/27

$700

Wed 5/75:45 pmSTL - OPO

2 stops15h 45mMultiple Airlines

Wed 5/146:20 amOPO - STL

2 stops20h 29mMultiple Airlines

Deal found 3/27

$826

Thu 4/244:05 pmSTL - OPO

2 stops19h 00mScandinavian Airlines

Fri 5/25:55 pmOPO - STL

2 stops35h 41mScandinavian Airlines

Deal found 3/26

$976

Tue 8/51:22 pmSTL - OPO

2 stops16h 18mAmerican Airlines

Tue 8/128:15 amOPO - STL

2 stops17h 32mAmerican Airlines

Deal found 3/27

$1,049

Sun 4/2710:17 amSTL - OPO

2 stops19h 23mIberia

Sun 5/412:20 pmOPO - STL

2 stops36h 13mIberia

Deal found 3/26

$1,109

Best flights from St. Louis to Porto
Discover carefully curated flight deals from St. Louis to Porto that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated March 28, 2025.

Wed 5/75:45 pmSTL - OPO

2 stops15h 45mMultiple Airlines

Wed 5/146:20 amOPO - STL

2 stops20h 29mMultiple Airlines

Deal found 3/27

$826

Fri 9/199:17 amSTL - OPO

2 stops15h 33mUnited Airlines

Thu 9/2512:10 pmOPO - STL

2 stops32h 08mUnited Airlines

Deal found 3/27

$842

Fri 4/257:01 pmSTL - OPO

2 stops21h 14mDelta

Mon 4/2811:25 amOPO - STL

2 stops35h 01mDelta

Deal found 3/27

$891

Fri 9/195:30 pmSTL - OPO

2 stops23h 50mLufthansa

Sat 9/2712:05 pmOPO - STL

2 stops33h 16mLufthansa

Deal found 3/27

$958

Thu 4/244:05 pmSTL - OPO

2 stops19h 00mScandinavian Airlines

Fri 5/25:55 pmOPO - STL

2 stops35h 41mScandinavian Airlines

Deal found 3/26

$976

Tue 8/51:22 pmSTL - OPO

2 stops16h 18mAmerican Airlines

Tue 8/128:15 amOPO - STL

2 stops17h 32mAmerican Airlines

Deal found 3/27

$1,049

Sun 4/2710:17 amSTL - OPO

2 stops19h 23mIberia

Sun 5/412:20 pmOPO - STL

2 stops36h 13mIberia

Deal found 3/26

$1,109

Last-minute flights from St. Louis to Porto
Discover last-minute flight deals from St. Louis to Porto. Data last updated March 28, 2025 and is based on user searches.

Thu 4/244:05 pmSTL - OPO

2 stops19h 00mScandinavian Airlines

Fri 5/25:55 pmOPO - STL

2 stops35h 41mScandinavian Airlines

Deal found 3/26

$976

Fri 4/257:01 pmSTL - OPO

2 stops21h 14mDelta

Mon 4/2811:25 amOPO - STL

2 stops35h 01mDelta

Deal found 3/27

$891

Fri 4/255:27 pmSTL - OPO

2 stops16h 28mAmerican Airlines

Thu 5/18:15 amOPO - STL

2 stops19h 57mAmerican Airlines

Deal found 3/27

$1,063

Sat 4/265:33 pmSTL - OPO

2 stops40h 07mLufthansa

Sat 5/34:35 pmOPO - STL

1 stop26h 55mLufthansa

Deal found 3/27

$1,011

Sat 4/264:25 pmSTL - OPO

1 stop11h 20mUnited Airlines

Sun 5/46:00 amOPO - STL

2 stops15h 47mUnited Airlines

Deal found 3/27

$1,304

Sat 4/266:00 pmSTL - OPO

2 stops35h 40mMultiple Airlines

Thu 5/14:35 pmOPO - STL

1 stop26h 55mMultiple Airlines

Deal found 3/26

$1,571

Sun 4/2710:17 amSTL - OPO

2 stops19h 23mIberia

Sun 5/412:20 pmOPO - STL

2 stops36h 13mIberia

Deal found 3/26

$1,109

One-way flights from St. Louis to Porto
Search for one-way flight options from St. Louis to Porto. Find affordable one-way fares based on user searches. Data last updated March 28, 2025.

Sat 6/145:27 pmSTL - OPO

2 stops35h 48mUnited Airlines

Deal found 3/27

$889

Sat 6/141:30 pmSTL - OPO

1 stop14h 05mAir Canada

Deal found 3/27

$918

Cheapflights Fare Finder

Use the filters below to find and compare flights from St. Louis to Porto that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Wed 5/7

5:45 pm-3:30 pm

2 stops15h 45m

Porto

Wed 5/14

6:20 am-8:49 pm

2 stops20h 29m

$826

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Fri 9/19

9:17 am-6:50 am

2 stops15h 33m

Porto

Thu 9/25

12:10 pm-2:18 pm

2 stops32h 08m

$842

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Fri 4/25

7:01 pm-10:15 pm

2 stops21h 14m

Porto

Mon 4/28

11:25 am-4:26 pm

2 stops35h 01m

$891

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Fri 9/19

5:30 pm-11:20 pm

2 stops23h 50m

Porto

Sat 9/27

12:05 pm-3:21 pm

2 stops33h 16m

$958

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Thu 4/24

4:05 pm-5:05 pm

2 stops19h 00m

Porto

Fri 5/2

5:55 pm-11:36 pm

2 stops35h 41m

$976

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Tue 8/5

1:22 pm-11:40 am

2 stops16h 18m

Porto

Tue 8/12

8:15 am-7:47 pm

2 stops17h 32m

$1,049

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sun 4/27

10:17 am-11:40 am

2 stops19h 23m

Porto

Sun 5/4

12:20 pm-6:33 pm

2 stops36h 13m

$1,109

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sat 6/14

5:27 pm-11:15 am

2 stops35h 48m

$889

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sat 6/14

1:30 pm-9:35 am

1 stop14h 05m

$918

Flights are sorted by cheapest round-trip flights first.

Deals found on 3/27

Most accurate provider: When it comes to deals on St. Louis-Porto flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on St. Louis-Porto flight deals on Cheapflights vs. FlightHub >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 FlightHub the most. FlightHub 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 month to book a flight from St. Louis to Porto?

Currently, January is the cheapest month in which you can book a flight from St. Louis to Porto (average of $523). Flying from St. Louis to Porto in June is currently the most expensive (average of $1,084). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

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

Unlike in the afternoon, when flights are generally more expensive, you can save up to 36% on flights from St. Louis to Porto by exploring options for tickets at noon.

Rainfall in Porto by month

In terms of precipitation, rainfall in Porto ranges from 0.7 - 7.7 inches per month. December is typically the wettest month, when rainfall can reach 7.7 in. July is typically the driest time to visit Porto when rainfall is around 0.7 in.

Temperature in Porto by month

If weather is an important factor for your trip to Porto, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 68.0 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 48.2 F).

Reviews of airlines servicing Porto

Delta

8.0

Very good

7,896 reviews

Reviews

1 / 20

10.0

Excellent

Aaron,Oct 2024

LAX - LHR

This was a flight operated by Virgin Atlantic in their Upper Class cabin. Overall, an outstanding experience.

Delta

8.0

Very good

7,896 reviews

Delta

8.0

Very good

7,896 reviews

Reviews

1 / 20

10.0

Excellent

Aaron,Oct 2024

LAX - LHR

This was a flight operated by Virgin Atlantic in their Upper Class cabin. Overall, an outstanding experience.

United Airlines

7.4

Good

8,603 reviews

Delta

8.0

Very good

7,896 reviews

Reviews

1 / 20

10.0

Excellent

Aaron,Oct 2024

LAX - LHR

This was a flight operated by Virgin Atlantic in their Upper Class cabin. Overall, an outstanding experience.

Scandinavian Airlines

7.3

Good

1,325 reviews

Delta

8.0

Very good

7,896 reviews

Reviews

1 / 20

10.0

Excellent

Aaron,Oct 2024

LAX - LHR

This was a flight operated by Virgin Atlantic in their Upper Class cabin. Overall, an outstanding experience.

American Airlines

7.2

Good

10,000 reviews

Delta

8.0

Very good

7,896 reviews

Reviews

1 / 20

10.0

Excellent

Aaron,Oct 2024

LAX - LHR

This was a flight operated by Virgin Atlantic in their Upper Class cabin. Overall, an outstanding experience.

Air Canada

7.0

Good

8,986 reviews

Delta

8.0

Very good

7,896 reviews

Reviews

1 / 20

10.0

Excellent

Aaron,Oct 2024

LAX - LHR

This was a flight operated by Virgin Atlantic in their Upper Class cabin. Overall, an outstanding experience.

Related info for your journey

What are the cheapest airlines flying from St. Louis to Porto round-trip?
United Airlines, at $842, was found to be the cheapest airline from St. Louis to Porto.Alternate airlines to your destination round-trip include Delta and Lufthansa. Users have found that United Airlines is 13% 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.
What is the cheapest month to book a flight from St. Louis to Porto?
Currently, January is the cheapest month in which you can book a flight from St. Louis to Porto (average of $523). Flying from St. Louis to Porto in June is currently the most expensive (average of $1,084). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

Aveiro

Coimbra

Matosinhos

Arcos de Valdevez

Browse thousands of different options on Cheapflights for your next trip

Alternative routes for St. Louis to Porto

Kansas City to Lisbon flights

St. Louis to Lisbon flights

Kansas City to Porto flights

Kansas City to Ponta Delgada flights

St. Louis to Lajes flights

Kansas City to Lajes flights

Other flights to Porto

Top 2 airlines flying from St. Louis to Porto

Airline	Cheapest	Average	Flexibility	On-time
United Airlines	Cheapest$711	Average$1,093	FlexibilityNo cancel fee	On-time69%
Delta	Cheapest$713	Average$963	FlexibilityNo cancel fee	On-timeN/A

100% Free

Cheapflights is completely free to use, so you can start saving the moment you arrive.

Book with Flexibility

Our users can plan ahead with confidence and find flights with no change fees

Travel Smart

Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.

$643+ 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 10/22. Fares are subject to change and may not be available on all flights or dates of travel.

Find cheap flights from St. Louis to Porto with Cheapflights

1. Tell us where you want to go

2. Select your favorite providers

3. Compare prices and book

Cheap flight deals from St. Louis to Porto

Most accurate provider

Most trusted provider

Round-trip from

Popular in

Cheapest in

Average price

Find flight deals from St. Louis to Porto

Cheapest flights from St. Louis to PortoExplore 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 March 28, 2025.

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 March 28, 2025.

Cheapflights Fare Finder

Use the filters below to find and compare flights from St. Louis to Porto that are best for you.

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.

Cheapflights Insights

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

What is the cheapest month to book a 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 March 28, 2025.

Rainfall in Porto by month

Plan your trip to Porto by taking into account the average rainfall totals by month.

Temperature in Porto by month

Plan your trip to Porto by taking into account the average temperature totals by month.

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 March 28, 2025.

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.

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

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

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

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

What is the cheapest month to book a flight from St. Louis to Porto?

Traveling to a place near St. Louis?

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for St. Louis to Porto

See prices for flight routes from nearby airports that may be better suited for you.

Top 2 airlines flying from St. Louis to Porto

100% Free

Book with Flexibility

Travel Smart

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 March 28, 2025.