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Cheap flights from St. Louis to Porto from $634

This is the cheapest round-trip flight price found by a momondo user in the last 72 hours by searching for a flight from St. Louis to Porto departing on 11/17. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.
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Cheap round-trip flights

United Airlines Logo
3:14 pm - 9:30 amSTL-OPO
12h 16m2 stops
United Airlines Logo
6:00 am - 1:55 pmOPO-STL
13h 55m1 stop
$634United Airlines
Find Deal
Mon, Nov 17 - Sun, Nov 23
Lufthansa Logo
11:49 am - 9:30 amSTL-OPO
15h 41m1 stop
Lufthansa Logo
6:00 am - 1:55 pmOPO-STL
13h 55m1 stop
$641Lufthansa
Find Deal
Mon, Nov 17 - Sun, Nov 23
United Airlines Logo
10:00 am - 9:30 amSTL-OPO
17h 30m2 stops
United Airlines Logo
6:00 am - 9:40 pmOPO-STL
21h 40m2 stops
$644United Airlines
Find Deal
Mon, Nov 10 - Sun, Nov 16
United Airlines Logo
9:00 am - 9:30 amSTL-OPO
18h 30m2 stops
United Airlines Logo
12:35 pm - 10:45 pmOPO-STL
16h 10m2 stops
$647United Airlines
Find Deal
Sun, Nov 16 - Sun, Nov 23
Lufthansa Logo
3:50 pm - 3:15 pmSTL-OPO
17h 25m1 stop
Lufthansa Logo
6:00 am - 1:55 pmOPO-STL
13h 55m1 stop
$650Lufthansa
Find Deal
Sun, Nov 16 - Sun, Nov 23
Lufthansa Logo
3:50 pm - 3:15 pmSTL-OPO
17h 25m1 stop
Lufthansa Logo
6:00 am - 1:55 pmOPO-STL
13h 55m1 stop
$651Lufthansa
Find Deal
Sun, Nov 16 - Sun, Nov 23
Iberia Logo
7:00 am - 7:40 amSTL-OPO
18h 40m2 stops
Iberia Logo
8:40 pm - 10:29 pmOPO-STL
31h 49m2 stops
$677Iberia
Find Deal
Sun, Nov 16 - Sat, Nov 22
KLM Logo
12:10 pm - 10:30 amSTL-OPO
16h 20m2 stops
KLM Logo
4:10 pm - 4:40 pmOPO-STL
30h 30m2 stops
$691KLM
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Sun, Nov 16 - Sat, Nov 22
Iberia Logo
8:03 pm - 7:55 pmSTL-OPO
17h 52m2 stops
Iberia Logo
8:35 pm - 8:26 pmOPO-STL
29h 51m2 stops
$778Iberia
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Sun, Sep 28 - Wed, Oct 15
British Airways Logo
4:48 pm - 4:40 pmSTL-OPO
17h 52m2 stops
British Airways Logo
8:20 am - 7:27 pmOPO-STL
17h 07m2 stops
$1,172British Airways
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Mon, Nov 10 - Fri, Nov 14

United Airlines flights from St. Louis to Porto

Our best United Airlines deals on St. Louis to Porto flight tickets
United Airlines
Nov 17
STL3:14 pmLambert-St Louis
12h 16m
2 stops
OPO9:30 amPorto
Nov 23
OPO6:00 amPorto
13h 55m
1 stop
STL1:55 pmLambert-St Louis
$634
Find similar
United Airlines
Nov 10
STL10:00 amLambert-St Louis
17h 30m
2 stops
OPO9:30 amPorto
Nov 16
OPO6:00 amPorto
21h 40m
2 stops
STL9:40 pmLambert-St Louis
$644
Find similar
United Airlines
Nov 16
STL9:00 amLambert-St Louis
18h 30m
2 stops
OPO9:30 amPorto
Nov 23
OPO12:35 pmPorto
16h 10m
2 stops
STL10:45 pmLambert-St Louis
$647
Find similar

Lufthansa flights from St. Louis to Porto

Our best Lufthansa deals on St. Louis to Porto flight tickets
Lufthansa
Nov 17
STL11:49 amLambert-St Louis
15h 41m
1 stop
OPO9:30 amPorto
Nov 23
OPO6:00 amPorto
13h 55m
1 stop
STL1:55 pmLambert-St Louis
$641
Find similar
Lufthansa
Nov 16
STL3:50 pmLambert-St Louis
17h 25m
1 stop
OPO3:15 pmPorto
Nov 23
OPO6:00 amPorto
13h 55m
1 stop
STL1:55 pmLambert-St Louis
$650
Find similar
Lufthansa
Nov 16
STL3:50 pmLambert-St Louis
17h 25m
1 stop
OPO3:15 pmPorto
Nov 23
OPO6:00 amPorto
13h 55m
1 stop
STL1:55 pmLambert-St Louis
$651
Find similar

momondo 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, momondo users made 832,500 searches. Data last updated July 31, 2025.
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

Mon 11/17

3:14 pm-9:30 am

2 stops12h 16m

Porto

Sun 11/23

6:00 am-1:55 pm

1 stop13h 55m

$634

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Mon 11/17

11:49 am-9:30 am

1 stop15h 41m

Porto

Sun 11/23

6:00 am-1:55 pm

1 stop13h 55m

$641

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Mon 11/10

10:00 am-9:30 am

2 stops17h 30m

Porto

Sun 11/16

6:00 am-9:40 pm

2 stops21h 40m

$644

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sun 11/16

9:00 am-9:30 am

2 stops18h 30m

Porto

Sun 11/23

12:35 pm-10:45 pm

2 stops16h 10m

$647

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sun 11/16

3:50 pm-3:15 pm

1 stop17h 25m

Porto

Sun 11/23

6:00 am-1:55 pm

1 stop13h 55m

$650

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sun 11/16

3:50 pm-3:15 pm

1 stop17h 25m

Porto

Sun 11/23

6:00 am-1:55 pm

1 stop13h 55m

$651

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sun 11/16

7:00 am-7:40 am

2 stops18h 40m

Porto

Sat 11/22

8:40 pm-10:29 pm

2 stops31h 49m

$677

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sun 11/16

12:10 pm-10:30 am

2 stops16h 20m

Porto

Sat 11/22

4:10 pm-4:40 pm

2 stops30h 30m

$691

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sun 9/28

8:03 pm-7:55 pm

2 stops17h 52m

Porto

Wed 10/15

8:35 pm-8:26 pm

2 stops29h 51m

$778

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Mon 11/10

4:48 pm-4:40 pm

2 stops17h 52m

Porto

Fri 11/14

8:20 am-7:27 pm

2 stops17h 07m

$1,172

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 15 resultsSorted by cheapest first
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See travel insights to Porto from

How to get the cheapest flight ticket from St. Louis to Porto

Look no further. We've gone through all the searches for this route on momondo so you have the important information and insights to find the cheapest flight ticket for your trip

What is the typical price of a round-trip flight between St. Louis and Porto?

What is the cheapest month to fly to Porto?

The month of November is, on average, the cheapest month to fly to Porto from St. Louis, with most prices found around $565. If you aren’t able to travel during the month of November, then book flights to Porto from St. Louis during February instead. Flights to Porto in February, while not as cheap as those in November, still average around $706.

What is the cheapest day to depart on your flight to Porto?

The cheapest day to depart on your flight to Porto is on a Thursday when prices can be found for as low as $752. This is often the case because there is less demand to fly during this day of the week. If your travel schedule is flexible, try to avoid departing on a Friday because tickets tend to average around $1,465. These prices are subject to change though, so be sure to set up a Price Alert for flights to Porto.

What is the cheapest time of day to depart on your flight to Porto?

At noon is the cheapest time of day to fly from St. Louis to Porto when you can find flight prices for as low as $752. Flying to Porto at noon is an ideal time because this is during off-peak travel hours. If you have a flexible travel schedule, then try to avoid flying in the afternoon when prices are $1,170 on average. Flights to Porto from St. Louis in the afternoon are generally more expensive because this time of day is more convenient for travelers’ schedules.

Can stopping save me money on St. Louis to Porto flights?

You could potentially save up to 26% on your flight if you consider stops on a St. Louis to Porto flight.

When to book flights from St. Louis to Porto

Are you open to changing your travel dates? Check out the ideal times to fly from St. Louis to Porto according to our flight data. Find out which month and days have the cheapest flights.
Estimated round-trip price

Cheap St. Louis to Porto (STL to OPO) flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from St. Louis to Porto

Best Price Found

$657

Fastest flight time

10h 21m

Direct flights

None

Airports in Porto

1 airport
The best one-way flight to Porto from St. Louis in the past 72 hours is $657. The best round-trip flight deal from St. Louis to Porto found on momondo in the last 72 hours is $634.
The fastest flight from St. Louis to Porto takes 10h 21m
There are no direct flights from St. Louis to Porto. Popular non-direct route for this connection is Lambert-St Louis Airport - Porto Airport.
There is 1 airport near Porto: Porto (OPO)
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  • How far is Lambert-St Louis to Porto by plane?

    There are 4156.0 mi between Lambert-St Louis and Porto. A reasonable flight in good conditions will take 10h 21m.

  • When did momondo last update prices for flights from Lambert-St Louis Airport to Porto Airport?

    Prices for flights from Lambert-St Louis Airport to Porto Airport are refreshed on a daily basis.

  • How many operators does momondo search for flights from Lambert-St Louis Airport to Porto Airport?

  • How old do you have to be to fly from Lambert-St Louis Airport to Porto Airport?

    The minimum age a child must be to fly alone is five but airlines that offer an unaccompanied minor (UNMR) service will have their own age restrictions, including rules around flight length, timings, and stopovers. We always recommend checking with the individual airline you are booking with to travel from Lambert-St Louis Airport to Porto Airport.

  • What documentation or ID do you need to fly to Porto Airport?

    The travel and health documents you'll need for your trip to Porto Airport may differ based on your itinerary and personal situation. Typically, you should have several documents on hand, such as a national ID card or driver's license and a passport that is valid for six months after your intended arrival at Porto Airport. It is always advisable to seek advice from your airline or a trusted third party, such as IATA.

  • What is the most popular airline from St. Louis to Porto?

Best airlines flying from St. Louis to Porto

Compare and see reviews for airlines that fly from St. Louis to Porto with momondo
Airline
Rating
Free Cancellation
Price
LufthansaPriceFrom $612Free CancellationRating
6.8
7,275 reviews
Search Lufthansa flights
DeltaPriceFrom $713Free CancellationRating
8.0
7,981 reviews
Search Delta flights
United AirlinesPriceFrom $751Free CancellationRating
7.4
8,900 reviews
Search United Airlines flights

Traveling to a place near Porto?

Book flights to Porto if you plan to visit one of these locations
Aveiro
Vila Nova de Gaia
Coimbra
Matosinhos
Braga
Caminha
Guimarães
Chaves
Esposende
Lamego
Arcos de Valdevez
Espinho
Viseu
Ponte de Lima
Santa Maria da Feira
Curia
Penafiel
Mesao Frio
Pinhao
Baiao

Why use momondo?

Why should I use momondo to find a flight deal from St. Louis to Porto?

Finding the right flight to Porto from St. Louis is quick and easy when you have a range of options in front of you, from reputable agents and recognisable airlines. Options that can then be filtered down to find the best fit. That is what momondo does. We make finding flights to Porto quick and easy, saving you time and money.

Can I find flights from St. Louis to Porto with flexible booking policies on momondo?

All flight searches from St. Louis to Porto on momondo can be filtered to show those which offer flexible booking policies.

How can momondo help me find flights from St. Louis to Porto?

momondo offers useful filters to help you find the right flight. Choose specific flight times, airports or even what payment method you prefer. We have numerous options to help you book your ideal flight from St. Louis to Porto.

I’m not ready to book a flight from St. Louis to Porto right now. Can momondo alert me if prices change?

Price alerts on flights to Porto from St. Louis are quick and easy to set up on momondo. Simply perform a search and select the price alert feature. It is as simple as that.

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