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Cheap flights from St. Louis to Porto from $538

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 8/29. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.
1 adult
0 bags

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Find the cheapest flights from St. Louis to Porto

Cheap round-trip flights

Enter your travel dates to find the best prices.
United Airlines Logo
7:30 am - 9:45 am
STL
-
OPO
20h 15m
1 stop
United Airlines Logo
12:45 pm - 9:24 pm
OPO
-
STL
38h 39m
2 stops
$829United Airlines
Sun, Oct 4 - Wed, Oct 21
United Airlines Logo
8:15 pm - 7:00 am
STL
-
OPO
28h 45m
2 stops
United Airlines Logo
12:45 pm - 12:20 pm
OPO
-
STL
29h 35m
2 stops
$832United Airlines
Sun, Oct 4 - Wed, Oct 21
United Airlines Logo
8:35 am - 9:45 am
STL
-
OPO
19h 10m
2 stops
United Airlines Logo
12:45 pm - 12:20 pm
OPO
-
STL
29h 35m
2 stops
$834United Airlines
Sun, Oct 4 - Wed, Oct 21
United Airlines Logo
7:30 am - 9:45 am
STL
-
OPO
20h 15m
1 stop
United Airlines Logo
12:45 pm - 6:41 pm
OPO
-
STL
11h 56m
1 stop
$842United Airlines
Sun, Oct 4 - Wed, Oct 21
United Airlines Logo
6:01 am - 6:55 am
STL
-
OPO
18h 54m
1 stop
United Airlines Logo
12:15 pm - 11:40 pm
OPO
-
STL
41h 25m
2 stops
$889United Airlines
Sun, Aug 9 - Sun, Aug 23
United Airlines Logo
10:20 am - 9:45 am
STL
-
OPO
17h 25m
2 stops
United Airlines Logo
12:15 pm - 3:38 pm
OPO
-
STL
33h 23m
2 stops
$894United Airlines
Sun, Aug 9 - Sun, Aug 23
United Airlines Logo
4:55 pm - 9:45 am
STL
-
OPO
10h 50m
1 stop
United Airlines Logo
12:15 pm - 6:42 pm
OPO
-
STL
12h 27m
1 stop
$902United Airlines
Sun, Aug 9 - Sun, Aug 23
United Airlines Logo
7:30 am - 9:45 am
STL
-
OPO
20h 15m
1 stop
United Airlines Logo
11:20 am - 8:37 pm
OPO
-
STL
39h 17m
2 stops
$957United Airlines
Wed, Oct 7 - Sat, Oct 17
United Airlines Logo
4:40 pm - 6:55 am
STL
-
OPO
32h 15m
2 stops
United Airlines Logo
12:20 pm - 3:38 pm
OPO
-
STL
33h 18m
2 stops
$962United Airlines
Sat, Sep 5 - Sat, Sep 26
United Airlines Logo
4:50 pm - 6:55 am
STL
-
OPO
32h 05m
1 stop
United Airlines Logo
12:20 pm - 4:26 pm
OPO
-
STL
34h 06m
2 stops
$963United Airlines
Sat, Sep 5 - Sat, Sep 26

KLM flights from St. Louis to Porto

Our best KLM deals on St. Louis to Porto flight tickets
KLM
Sep 5
STL1:30 pmLambert-St Louis
14h 50m
2 stops
OPO10:20 amPorto
Sep 13
OPO6:30 amPorto
16h 25m
2 stops
STL4:55 pmLambert-St Louis
$1,052
KLM
Sep 5
STL1:30 pmLambert-St Louis
14h 50m
2 stops
OPO10:20 amPorto
Sep 13
OPO12:25 pmPorto
34h 30m
1 stop
STL4:55 pmLambert-St Louis
$1,060
KLM
Sep 5
STL1:30 pmLambert-St Louis
14h 50m
2 stops
OPO10:20 amPorto
Sep 13
OPO6:30 amPorto
16h 25m
2 stops
STL4:55 pmLambert-St Louis
$1,120

United Airlines flights from St. Louis to Porto

Our best United Airlines deals on St. Louis to Porto flight tickets
United Airlines
Oct 4
STL7:30 amLambert-St Louis
20h 15m
1 stop
OPO9:45 amPorto
Oct 21
OPO12:45 pmPorto
38h 39m
2 stops
STL9:24 pmLambert-St Louis
$829
United Airlines
Oct 4
STL8:15 pmLambert-St Louis
28h 45m
2 stops
OPO7:00 amPorto
Oct 21
OPO12:45 pmPorto
29h 35m
2 stops
STL12:20 pmLambert-St Louis
$832
United Airlines
Oct 4
STL8:35 amLambert-St Louis
19h 10m
2 stops
OPO9:45 amPorto
Oct 21
OPO12:45 pmPorto
38h 39m
2 stops
STL9:24 pmLambert-St Louis
$834

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 May 12, 2026.
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

Cheapest round-trip

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sun 10/4

7:30 am-9:45 am

1 stop20h 15m

Porto

Wed 10/21

12:45 pm-9:24 pm

2 stops38h 39m

$829

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sun 10/4

8:15 pm-7:00 am

2 stops28h 45m

Porto

Wed 10/21

12:45 pm-12:20 pm

2 stops29h 35m

$832

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sun 10/4

8:35 am-9:45 am

2 stops19h 10m

Porto

Wed 10/21

12:45 pm-12:20 pm

2 stops29h 35m

$834

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sun 10/4

7:30 am-9:45 am

1 stop20h 15m

Porto

Wed 10/21

12:45 pm-6:41 pm

1 stop11h 56m

$842

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sun 8/9

6:01 am-6:55 am

1 stop18h 54m

Porto

Sun 8/23

12:15 pm-11:40 pm

2 stops41h 25m

$889

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sun 8/9

10:20 am-9:45 am

2 stops17h 25m

Porto

Sun 8/23

12:15 pm-3:38 pm

2 stops33h 23m

$894
Quickest round-trip

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sun 8/9

4:55 pm-9:45 am

1 stop10h 50m

Porto

Sun 8/23

12:15 pm-6:42 pm

1 stop12h 27m

$902

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Wed 10/7

7:30 am-9:45 am

1 stop20h 15m

Porto

Sat 10/17

11:20 am-8:37 pm

2 stops39h 17m

$957

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sat 9/5

4:40 pm-6:55 am

2 stops32h 15m

Porto

Sat 9/26

12:20 pm-3:38 pm

2 stops33h 18m

$962

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sat 9/5

4:50 pm-6:55 am

1 stop32h 05m

Porto

Sat 9/26

12:20 pm-4:26 pm

2 stops34h 06m

$963

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

What is the cheapest month to fly to Porto?

The month of December is, on average, the cheapest month to fly to Porto from St. Louis, with most prices found around $0. If you aren’t able to travel during the month of December, then book flights to Porto from St. Louis during January instead. Flights to Porto in January, while not as cheap as those in December, still average around $510.

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

You could potentially save up to 66% 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

Fastest flight time

11h 30m

Direct flights

None
The fastest flight from St. Louis to Porto takes 11h 30m
There are no direct flights from St. Louis to Porto. There are no popular flight routes from St. Louis to Porto.
Search flight deals

Frequently asked questions about flying from St. Louis to Porto

  • 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 11h 30m.

  • 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 $493Free CancellationRating
6.8
7,992 reviews
Search Lufthansa flights
United AirlinesPriceFrom $713Free CancellationRating
7.4
9,701 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
Coimbra
Braga
Aveiro
Matosinhos
Lamego
Esposende
Chaves
Pinhao
Espinho
Guimarães
Arcos de Valdevez
Viseu
Ponte de Lima
Curia
Penafiel
Mesao Frio
Mira
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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