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Cheap flights from St. Louis to Porto from $366

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from St. Louis to Porto departing on 12/9. 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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0 bags

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Find the cheapest flights from St. Louis to Porto

Cheap round-trip flights

Multiple Airlines Logo
3:14 pm - 9:30 amSTL-OPO
13h 16m2 stops
Multiple Airlines Logo
6:00 am - 1:55 pmOPO-STL
13h 55m1 stop
$508Multiple Airlines
Find Deal
Mon, Oct 27 - Wed, Nov 12
Lufthansa Logo
3:50 pm - 11:40 amSTL-OPO
13h 50m1 stop
Lufthansa Logo
6:00 am - 1:55 pmOPO-STL
13h 55m1 stop
$522Lufthansa
Find Deal
Wed, Nov 12 - Wed, Nov 19
United Airlines Logo
8:20 am - 9:30 amSTL-OPO
20h 10m2 stops
United Airlines Logo
6:00 am - 4:35 pmOPO-STL
40h 35m2 stops
$532United Airlines
Find Deal
Mon, Oct 27 - Wed, Nov 12
United Airlines Logo
11:05 am - 9:30 amSTL-OPO
16h 25m2 stops
United Airlines Logo
6:00 am - 1:55 pmOPO-STL
13h 55m1 stop
$534United Airlines
Find Deal
Wed, Nov 12 - Wed, Nov 19
British Airways Logo
12:52 pm - 7:40 amSTL-OPO
13h 48m2 stops
British Airways Logo
8:20 am - 8:23 pmOPO-STL
18h 03m2 stops
$551British Airways
Find Deal
Mon, Oct 27 - Wed, Nov 12
Delta Logo
9:04 am - 10:30 amSTL-OPO
19h 26m2 stops
Delta Logo
11:25 am - 8:24 amOPO-STL
26h 59m2 stops
$577Delta
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Sun, Nov 9 - Wed, Nov 19
Delta Logo
9:04 am - 10:30 amSTL-OPO
19h 26m2 stops
Delta Logo
11:20 am - 9:46 amOPO-STL
28h 26m2 stops
$583Delta
Find Deal
Sun, Nov 9 - Fri, Nov 21
British Airways Logo
12:51 pm - 7:40 amSTL-OPO
13h 49m2 stops
British Airways Logo
8:20 am - 11:56 pmOPO-STL
21h 36m2 stops
$608British Airways
Find Deal
Thu, Oct 30 - Thu, Nov 6
Air Canada Logo
4:05 pm - 11:15 amSTL-OPO
37h 10m2 stops
Air Canada Logo
6:00 am - 3:29 pmOPO-STL
39h 29m2 stops
$640Air Canada
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Mon, Nov 10 - Sat, Nov 22
Air Canada Logo
4:05 pm - 11:40 amSTL-OPO
37h 35m2 stops
Air Canada Logo
6:00 am - 3:29 pmOPO-STL
39h 29m2 stops
$649Air Canada
Find Deal
Tue, Nov 11 - Sat, Nov 22

United Airlines flights from St. Louis to Porto

Our best United Airlines deals on St. Louis to Porto flight tickets
United Airlines
Oct 27
STL8:20 amLambert-St Louis
20h 10m
2 stops
OPO9:30 amPorto
Nov 12
OPO6:00 amPorto
40h 35m
2 stops
STL4:35 pmLambert-St Louis
$532
Find similar
United Airlines
Nov 12
STL11:05 amLambert-St Louis
16h 25m
2 stops
OPO9:30 amPorto
Nov 19
OPO6:00 amPorto
13h 55m
1 stop
STL1:55 pmLambert-St Louis
$534
Find similar
United Airlines
Nov 12
STL10:00 amLambert-St Louis
17h 30m
2 stops
OPO9:30 amPorto
Nov 19
OPO6:00 amPorto
21h 54m
2 stops
STL9:54 pmLambert-St Louis
$544
Find similar

Lufthansa flights from St. Louis to Porto

Our best Lufthansa deals on St. Louis to Porto flight tickets
Lufthansa
Nov 12
STL3:50 pmLambert-St Louis
13h 50m
1 stop
OPO11:40 amPorto
Nov 19
OPO6:00 amPorto
13h 55m
1 stop
STL1:55 pmLambert-St Louis
$522
Find similar
Lufthansa
Nov 12
STL3:50 pmLambert-St Louis
17h 35m
1 stop
OPO3:25 pmPorto
Nov 18
OPO4:15 pmPorto
27h 40m
1 stop
STL1:55 pmLambert-St Louis
$572
Find similar
Lufthansa
Oct 30
STL11:49 amLambert-St Louis
16h 41m
1 stop
OPO9:30 amPorto
Nov 6
OPO12:30 pmPorto
31h 25m
1 stop
STL1:55 pmLambert-St Louis
$611
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 September 16, 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 10/27

3:14 pm-9:30 am

2 stops13h 16m

Porto

Wed 11/12

6:00 am-1:55 pm

1 stop13h 55m

$508

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Wed 11/12

3:50 pm-11:40 am

1 stop13h 50m

Porto

Wed 11/19

6:00 am-1:55 pm

1 stop13h 55m

$522

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Mon 10/27

8:20 am-9:30 am

2 stops20h 10m

Porto

Wed 11/12

6:00 am-4:35 pm

2 stops40h 35m

$532

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Wed 11/12

11:05 am-9:30 am

2 stops16h 25m

Porto

Wed 11/19

6:00 am-1:55 pm

1 stop13h 55m

$534

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Mon 10/27

12:52 pm-7:40 am

2 stops13h 48m

Porto

Wed 11/12

8:20 am-8:23 pm

2 stops18h 03m

$551

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sun 11/9

9:04 am-10:30 am

2 stops19h 26m

Porto

Wed 11/19

11:25 am-8:24 am

2 stops26h 59m

$577

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sun 11/9

9:04 am-10:30 am

2 stops19h 26m

Porto

Fri 11/21

11:20 am-9:46 am

2 stops28h 26m

$583

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Thu 10/30

12:51 pm-7:40 am

2 stops13h 49m

Porto

Thu 11/6

8:20 am-11:56 pm

2 stops21h 36m

$608

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Mon 11/10

4:05 pm-11:15 am

2 stops37h 10m

Porto

Sat 11/22

6:00 am-3:29 pm

2 stops39h 29m

$640

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Tue 11/11

4:05 pm-11:40 am

2 stops37h 35m

Porto

Sat 11/22

6:00 am-3:29 pm

2 stops39h 29m

$649

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 18 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 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 $636. 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 7% 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

Direct flights

None
There are no direct flights from St. Louis to Porto. There are no popular flight routes from St. Louis to Porto.
Search flight deals

  • 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 $601Free CancellationRating
6.8
7,407 reviews
Search Lufthansa flights
United AirlinesPriceFrom $751Free CancellationRating
7.4
8,924 reviews
Search United Airlines flights

Traveling to a place near Porto?

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

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.

An easier way to manage your Porto trip

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