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Cheap flights from St. Louis to Porto from $297

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 8/1. 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
1 adult, Economy, 0 bags

Discover deals from 900+ travel sites with momondo.

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 - 9:30 am
STL
-
OPO
20h 00m
1 stop
United Airlines Logo
6:00 am - 1:45 pm
OPO
-
STL
13h 45m
1 stop
$734United Airlines
Mon, Nov 16 - Fri, Nov 20
United Airlines Logo
7:30 am - 9:30 am
STL
-
OPO
20h 00m
1 stop
United Airlines Logo
6:00 am - 1:45 pm
OPO
-
STL
13h 45m
1 stop
$735United Airlines
Mon, Nov 16 - Fri, Nov 20
United Airlines Logo
6:00 am - 9:30 am
STL
-
OPO
21h 30m
2 stops
United Airlines Logo
6:00 am - 1:45 pm
OPO
-
STL
13h 45m
1 stop
$739United Airlines
Mon, Nov 16 - Fri, Nov 20
Multiple Airlines Logo
4:13 pm - 9:05 am
STL
-
OPO
10h 52m
1 stop
Multiple Airlines Logo
9:55 am - 8:37 pm
OPO
-
STL
16h 42m
2 stops
$746Multiple Airlines
Wed, Nov 4 - Tue, Nov 10
United Airlines Logo
1:08 pm - 9:30 am
STL
-
OPO
14h 22m
2 stops
United Airlines Logo
6:00 am - 6:06 pm
OPO
-
STL
18h 06m
2 stops
$749United Airlines
Mon, Nov 16 - Fri, Nov 20
Delta Logo
10:15 am - 10:35 am
STL
-
OPO
18h 20m
2 stops
Delta Logo
5:00 am - 8:37 pm
OPO
-
STL
21h 37m
2 stops
$750Delta
Wed, Nov 4 - Tue, Nov 10
Air Canada Logo
4:05 pm - 6:30 pm
STL
-
OPO
20h 25m
2 stops
Air Canada Logo
6:00 am - 3:26 pm
OPO
-
STL
39h 26m
2 stops
$754Air Canada
Mon, Nov 16 - Fri, Nov 20
United Airlines Logo
5:20 pm - 9:30 am
STL
-
OPO
10h 10m
1 stop
United Airlines Logo
12:35 pm - 11:09 pm
OPO
-
STL
16h 34m
2 stops
$759United Airlines
Sun, Dec 6 - Tue, Dec 8
Air Canada Logo
12:10 pm - 7:00 am
STL
-
OPO
12h 50m
1 stop
Air Canada Logo
11:50 am - 3:38 pm
OPO
-
STL
33h 48m
2 stops
$887Air Canada
Mon, Aug 10 - Thu, Aug 20
Multiple Airlines Logo
12:10 pm - 7:00 am
STL
-
OPO
12h 50m
1 stop
Multiple Airlines Logo
11:50 am - 6:42 pm
OPO
-
STL
12h 52m
1 stop
$888Multiple Airlines
Mon, Aug 10 - Thu, Aug 20

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Air Canada flights from St. Louis to Porto

Our best Air Canada deals on St. Louis to Porto flight tickets
Air Canada
Nov 16
STL4:05 pmLambert-St Louis
20h 25m
2 stops
OPO6:30 pmPorto
Nov 20
OPO6:00 amPorto
39h 26m
2 stops
STL3:26 pmLambert-St Louis
$754
Air Canada
Aug 10
STL12:10 pmLambert-St Louis
12h 50m
1 stop
OPO7:00 amPorto
Aug 20
OPO11:50 amPorto
33h 48m
2 stops
STL3:38 pmLambert-St Louis
$887
Air Canada
Aug 9
STL7:05 pmLambert-St Louis
29h 55m
2 stops
OPO7:00 amPorto
Aug 19
OPO11:20 amPorto
41h 39m
2 stops
STL10:59 pmLambert-St Louis
$897

United Airlines flights from St. Louis to Porto

Our best United Airlines deals on St. Louis to Porto flight tickets
United Airlines
Nov 16
STL7:30 amLambert-St Louis
20h 00m
1 stop
OPO9:30 amPorto
Nov 20
OPO6:00 amPorto
13h 45m
1 stop
STL1:45 pmLambert-St Louis
$734
United Airlines
Nov 16
STL7:30 amLambert-St Louis
20h 00m
1 stop
OPO9:30 amPorto
Nov 20
OPO6:00 amPorto
13h 45m
1 stop
STL1:45 pmLambert-St Louis
$735
United Airlines
Nov 16
STL6:00 amLambert-St Louis
21h 30m
2 stops
OPO9:30 amPorto
Nov 20
OPO6:00 amPorto
13h 45m
1 stop
STL1:45 pmLambert-St Louis
$739

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 June 28, 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

Mon 11/16

7:30 am-9:30 am

1 stop20h 00m

Porto

Fri 11/20

6:00 am-1:45 pm

1 stop13h 45m

$734

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Mon 11/16

7:30 am-9:30 am

1 stop20h 00m

Porto

Fri 11/20

6:00 am-1:45 pm

1 stop13h 45m

$735

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Mon 11/16

6:00 am-9:30 am

2 stops21h 30m

Porto

Fri 11/20

6:00 am-1:45 pm

1 stop13h 45m

$739

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Wed 11/4

4:13 pm-9:05 am

1 stop10h 52m

Porto

Tue 11/10

9:55 am-8:37 pm

2 stops16h 42m

$746

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Mon 11/16

1:08 pm-9:30 am

2 stops14h 22m

Porto

Fri 11/20

6:00 am-6:06 pm

2 stops18h 06m

$749

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Wed 11/4

10:15 am-10:35 am

2 stops18h 20m

Porto

Tue 11/10

5:00 am-8:37 pm

2 stops21h 37m

$750

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Mon 11/16

4:05 pm-6:30 pm

2 stops20h 25m

Porto

Fri 11/20

6:00 am-3:26 pm

2 stops39h 26m

$754

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sun 12/6

5:20 pm-9:30 am

1 stop10h 10m

Porto

Tue 12/8

12:35 pm-11:09 pm

2 stops16h 34m

$759

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Mon 8/10

12:10 pm-7:00 am

1 stop12h 50m

Porto

Thu 8/20

11:50 am-3:38 pm

2 stops33h 48m

$887
Quickest round-trip

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Mon 8/10

12:10 pm-7:00 am

1 stop12h 50m

Porto

Thu 8/20

11:50 am-6:42 pm

1 stop12h 52m

$888

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 20 resultsSorted by cheapest first
1
2

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 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 13% 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

10h 52m

Direct flights

None
The fastest flight from St. Louis to Porto takes 10h 52m
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 10h 52m.

  • 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
8,103 reviews
Search Lufthansa flights
United AirlinesPriceFrom $655Free CancellationRating
7.4
9,896 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
Guimarães
Arcos de Valdevez
Espinho
Ponte de Lima
Viseu
Curia
Mesao Frio
Penafiel
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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