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Cheap flights from St. Louis to Porto from $491

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 2/14. 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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Cheap round-trip flights

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Delta Logo
7:10 am - 10:30 amSTL-OPO
21h 20m2 stops
Delta Logo
6:00 am - 11:25 pmOPO-STL
23h 25m2 stops
$491Delta
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Sat, Feb 14 - Sat, Feb 21
KLM Logo
11:55 am - 10:30 amSTL-OPO
16h 35m2 stops
KLM Logo
6:00 am - 8:45 pmOPO-STL
20h 45m2 stops
$492KLM
Find Deal
Sat, Feb 14 - Sat, Feb 21
United Airlines Logo
4:50 pm - 2:45 pmSTL-OPO
16h 55m1 stop
United Airlines Logo
6:00 am - 7:25 pmOPO-STL
19h 25m2 stops
$738United Airlines
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Fri, Mar 27 - Tue, Mar 31
Lufthansa Logo
4:50 pm - 2:45 pmSTL-OPO
16h 55m1 stop
Lufthansa Logo
6:00 am - 7:48 pmOPO-STL
19h 48m2 stops
$739Lufthansa
Find Deal
Fri, Mar 27 - Tue, Mar 31
Lufthansa Logo
4:50 pm - 2:45 pmSTL-OPO
16h 55m1 stop
Lufthansa Logo
12:00 pm - 1:30 pmOPO-STL
31h 30m1 stop
$749Lufthansa
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Fri, Mar 27 - Tue, Mar 31
United Airlines Logo
6:00 am - 9:30 amSTL-OPO
22h 30m2 stops
United Airlines Logo
6:00 am - 7:25 pmOPO-STL
19h 25m2 stops
$777United Airlines
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Fri, Mar 27 - Tue, Mar 31
Multiple Airlines Logo
4:05 pm - 10:10 pmSTL-OPO
24h 05m2 stops
Multiple Airlines Logo
8:50 am - 3:29 pmOPO-STL
12h 39m1 stop
$1,061Multiple Airlines
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Sat, Feb 14 - Sat, Feb 21
Multiple Airlines Logo
4:05 pm - 10:10 pmSTL-OPO
24h 05m2 stops
Multiple Airlines Logo
8:50 am - 11:01 amOPO-STL
32h 11m3 stops
$1,063Multiple Airlines
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Sat, Feb 14 - Sat, Feb 21
Iberia Logo
12:01 pm - 4:00 pmSTL-OPO
22h 59m2 stops
Iberia Logo
12:25 pm - 8:58 amOPO-STL
25h 33m2 stops
$1,337Iberia
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Fri, Mar 13 - Sat, Mar 21
Iberia Logo
10:03 am - 4:00 pmSTL-OPO
23h 57m2 stops
Iberia Logo
8:20 am - 6:03 pmOPO-STL
15h 43m2 stops
$1,339Iberia
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Sat, Feb 14 - Sat, Feb 21

KLM flights from St. Louis to Porto

Our best KLM deals on St. Louis to Porto flight tickets
KLM
Feb 14
STL11:55 amLambert-St Louis
16h 35m
2 stops
OPO10:30 amPorto
Feb 21
OPO6:00 amPorto
20h 45m
2 stops
STL8:45 pmLambert-St Louis
$492
Find similar
KLM
Mar 13
STL11:51 amLambert-St Louis
17h 39m
2 stops
OPO10:30 amPorto
Mar 21
OPO9:25 amPorto
28h 39m
2 stops
STL9:04 amLambert-St Louis
$1,312
Find similar
KLM
Nov 6
STL7:05 amLambert-St Louis
21h 25m
2 stops
OPO10:30 amPorto
Nov 7
OPO4:10 pmPorto
35h 54m
2 stops
STL10:04 pmLambert-St Louis
$2,051
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Lufthansa flights from St. Louis to Porto

Our best Lufthansa deals on St. Louis to Porto flight tickets
Lufthansa
Mar 27
STL4:50 pmLambert-St Louis
16h 55m
1 stop
OPO2:45 pmPorto
Mar 31
OPO6:00 amPorto
19h 48m
2 stops
STL7:48 pmLambert-St Louis
$739
Find similar
Lufthansa
Mar 27
STL4:50 pmLambert-St Louis
16h 55m
1 stop
OPO2:45 pmPorto
Mar 31
OPO12:00 pmPorto
31h 30m
1 stop
STL1:30 pmLambert-St Louis
$749
Find similar
Lufthansa
Dec 18
STL6:35 pmLambert-St Louis
23h 05m
2 stops
OPO11:40 pmPorto
Dec 25
OPO4:15 pmPorto
27h 40m
1 stop
STL1:55 pmLambert-St Louis
$1,576
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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 November 5, 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

Sat 2/14

7:10 am-10:30 am

2 stops21h 20m

Porto

Sat 2/21

6:00 am-11:25 pm

2 stops23h 25m

$491

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sat 2/14

11:55 am-10:30 am

2 stops16h 35m

Porto

Sat 2/21

6:00 am-8:45 pm

2 stops20h 45m

$492

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Fri 3/27

4:50 pm-2:45 pm

1 stop16h 55m

Porto

Tue 3/31

6:00 am-7:25 pm

2 stops19h 25m

$738

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Fri 3/27

4:50 pm-2:45 pm

1 stop16h 55m

Porto

Tue 3/31

6:00 am-7:48 pm

2 stops19h 48m

$739

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Fri 3/27

4:50 pm-2:45 pm

1 stop16h 55m

Porto

Tue 3/31

12:00 pm-1:30 pm

1 stop31h 30m

$749

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Fri 3/27

6:00 am-9:30 am

2 stops22h 30m

Porto

Tue 3/31

6:00 am-7:25 pm

2 stops19h 25m

$777

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sat 2/14

4:05 pm-10:10 pm

2 stops24h 05m

Porto

Sat 2/21

8:50 am-3:29 pm

1 stop12h 39m

$1,061

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sat 2/14

4:05 pm-10:10 pm

2 stops24h 05m

Porto

Sat 2/21

8:50 am-11:01 am

3 stops32h 11m

$1,063

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Fri 3/13

12:01 pm-4:00 pm

2 stops22h 59m

Porto

Sat 3/21

12:25 pm-8:58 am

2 stops25h 33m

$1,337

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sat 2/14

10:03 am-4:00 pm

2 stops23h 57m

Porto

Sat 2/21

8:20 am-6:03 pm

2 stops15h 43m

$1,339

Flights are sorted by cheapest round-trip flights first.

Sorted by cheapest first

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 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 35% 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.
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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 50m.

  • 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 $549Free CancellationRating
6.8
7,555 reviews
Search Lufthansa flights
United AirlinesPriceFrom $751Free CancellationRating
7.4
9,002 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
Aveiro
Matosinhos
Braga
Lamego
Guimarães
Esposende
Chaves
Espinho
Viseu
Ponte de Lima
Arcos de Valdevez
Pinhao
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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