STL - OPO

$345 Find Cheap Flights from St. Louis to Porto

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from St. Louis to Porto departing on 3/29. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy, 0 bags

KAYAK searches hundreds of travel sites at once for deals on flights to Porto

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from St. Louis to Porto, as well as popular online travel agencies
These are the airlines KAYAK users have selected most often from within our search results in flight searches from St. Louis to Porto, as well as popular online travel agencies
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Everything you should know

Cheapest round-trip
$502
Typical prices: $1,267-$1,378
United Airlines
Fri 1/23Tue 1/27
STL - OPO • 1 stop
Cheapest one-way
$345
Multiple Airlines
Sun 3/29
STL - OPO • 2 stops
Top airlines
Delta
Cheapest • from $493 (round-trip)
Delta
Best reviews • 7.9 score
Airline reviews
Airline reviews
+1
+1
Airline reviews
Airline reviews
+1
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Flight Deals
Booking Insights
Flight Deals

Cheap Flights from St. Louis to Porto (STL-OPO)

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from St. Louis to Porto that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from St. Louis to Porto

Fri, Jan 23 - Tue, Jan 27
United Airlines Logo
3:50 pm - 11:40 am
STL
-
OPO
13h 50m1 stop
United Airlines Logo
6:00 am - 11:02 am
OPO
-
STL
35h 02m2 stops
$502United Airlines
Fri, Jan 23 - Tue, Jan 27
United Airlines Logo
9:57 am - 11:40 am
STL
-
OPO
19h 43m2 stops
United Airlines Logo
6:00 am - 2:30 pm
OPO
-
STL
38h 30m2 stops
$506United Airlines
Mon, May 25 - Thu, Jun 4
Multiple Airlines Logo
5:00 pm - 10:30 am
STL
-
OPO
11h 30m1 stop
Multiple Airlines Logo
5:00 am - 4:45 pm
OPO
-
STL
17h 45m2 stops
$792Multiple Airlines
Mon, May 25 - Thu, Jun 4
Multiple Airlines Logo
5:00 pm - 3:25 pm
STL
-
OPO
16h 25m2 stops
Multiple Airlines Logo
5:00 am - 4:45 pm
OPO
-
STL
17h 45m2 stops
$796Multiple Airlines
Thu, Apr 16 - Tue, Apr 21
United Airlines Logo
6:30 am - 9:45 am
STL
-
OPO
21h 15m2 stops
United Airlines Logo
12:35 pm - 10:23 am
OPO
-
STL
27h 48m2 stops
$798United Airlines
Mon, May 25 - Thu, Jun 4
Multiple Airlines Logo
5:00 pm - 10:30 am
STL
-
OPO
11h 30m1 stop
Multiple Airlines Logo
12:25 pm - 4:40 pm
OPO
-
STL
34h 15m1 stop
$806Multiple Airlines
Mon, Mar 30 - Mon, Apr 6
United Airlines Logo
5:20 pm - 9:45 am
STL
-
OPO
10h 25m1 stop
United Airlines Logo
12:00 pm - 8:45 pm
OPO
-
STL
38h 45m2 stops
$946United Airlines
Mon, Mar 30 - Mon, Apr 6
United Airlines Logo
11:25 am - 9:45 am
STL
-
OPO
16h 20m2 stops
United Airlines Logo
12:00 pm - 10:19 pm
OPO
-
STL
40h 19m2 stops
$950United Airlines
Mon, Mar 30 - Mon, Apr 6
United Airlines Logo
6:30 am - 3:40 pm
STL
-
OPO
27h 10m3 stops
United Airlines Logo
12:00 pm - 8:45 pm
OPO
-
STL
38h 45m2 stops
$965United Airlines
Mon, Mar 30 - Mon, Apr 6
Lufthansa Logo
11:45 am - 9:45 am
STL
-
OPO
16h 00m1 stop
Lufthansa Logo
12:35 pm - 4:40 pm
OPO
-
STL
34h 05m1 stop
$1,031Lufthansa
Booking Insights

KAYAK's insights & trends for St. Louis to Porto flights

Get data-powered insights and trends into flights from St. Louis to Porto to help you find the cheapest flights, the best time to fly and much more.

Which airlines provide the cheapest flights from St. Louis to Porto?

The cheapest round-trip price for the route for each airline clicked by KAYAK users in the last 72 hours.

In the past 3 days, the cheapest round-trip tickets from St. Louis to Porto were found on Delta ($493) and United Airlines ($502).

Which airlines fly non-stop between St. Louis and Porto?

Airline and price data is aggregated from results in KAYAK’s search results from the last 2 weeks for round-trip flights from St. Louis to Porto.

There are 4 airlines that fly nonstop from St. Louis to Porto. They are: Air Canada, Delta, Lufthansa and United Airlines. The cheapest price of all airlines flying this route was found with Lufthansa at $520 for a round-trip flight. On average, the best prices for this route can be found at Delta.

Good to know

Low seasonFebruary
Cheapest flight$345
Best time to beat the crowds with an average 51% drop in price.
Most popular time to fly with an average 11% increase in price.
Flight from St. Louis to Porto

When to book flights from St. Louis to Porto

Are your dates flexible? Find out the best times to travel from St. Louis to Porto based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price
KAYAK looks at all historical flight data for each date to provide a predicted price for one-way trips or round-trips with a duration up to 40 days. While we try to provide actual minimum prices for each date, some prices are predictions and actual prices may differ.

FAQs for booking flights from St. Louis to Porto

  • What is the cheapest flight from St. Louis to Porto?

    In the last 3 days, the lowest price for a flight from St. Louis to Porto was $345 for a one-way ticket and $493 for a round-trip.

  • Do I need a passport to fly between St. Louis and Porto?

    Yes, you’ll need a passport to travel to Porto from St. Louis.

  • Which airports will I be using when flying from St. Louis to Porto?

    St. Louis and Porto are both served by 1 main airport. You will leave St. Louis from Lambert-St Louis and will be arriving at Porto.

  • Which aircraft models fly most regularly from St. Louis to Porto?

    We unfortunately don’t have that data for this specific route.

  • Which airline alliances offer flights from St. Louis to Porto?

    SkyTeam, and Star Alliance are the airline alliances operating flights between St. Louis and Porto, with SkyTeam being the most commonly used for this route.

  • Which is the best airline for flights from St. Louis to Porto, Delta or United Airlines?

    The two airlines most popular with KAYAK users for flights from St. Louis to Porto are Delta and United Airlines. With an average price for the route of $963 and an overall rating of 7.9, Delta is the most popular choice. United Airlines is also a great choice for the route, with an average price of $1,095 and an overall rating of 7.4.

  • How does KAYAK find such low prices on flights from St. Louis to Porto?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from St. Louis to Porto.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from St. Louis to Porto?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to Porto from St. Louis is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from St. Louis to Porto?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly to Porto with an airline and back to St. Louis with another airline. Booking your flights between St. Louis and OPO can sometimes prove cheaper using this method.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from St. Louis to Porto?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying to Porto from St. Louis up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

Reviews of the top 4 airlines serving from St. Louis to Porto

 
See real verified KAYAK customer reviews for airlines flying from St. Louis to Porto. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from St. Louis to Porto? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
7.9
DeltaOverall score based on 8007 reviews
7.9Comfort
8.5Crew
7.3Food
8.1Boarding
7.9Entertainment
Airline reviews

I noticed that the planes seem to be outdated. There was no entertainment per se. Also, the waiting area did not have any working electrical outlets

10.0 ExcellentMargaret, Dec 2025
BOS - PIT
Read more Delta reviews

I noticed that the planes seem to be outdated. There was no entertainment per se. Also, the waiting area did not have any working electrical outlets

None of the airplane features were available during the flight.

Original flight was cancelled and when i was rebooked by the airline, they couldn't seat me in the same type of seat as I had originally booked (went from window/aisle to middle/middle and one was a bulkhead seat, and other wasn't in the same class)

Lady Pilot was perfect in every way wheels up to wheels down communication, professionalism, excellent on time departure and on time arrival, excellent communication! Fantastic job with Superb attitude!!

The food is terrible. The staff is wonderful. Comfort is good.

Left on time, a bit delayed due to headwinds most of the trip.

I fly Delta all the time, have Platinum Medallion status. But this route seems to have major problems with delays and seems to never leave on time! Have only taken it twice in the last two weeks, and each time it had delays of more than 1 hour... very disappointed!!!!

Getting to the flight was arduous and lengthy. The flight itself was good but the food option wasn’t a good selection. I need to do a Kosher option on my return. Flight crew were nice

Good seats in Main cabin, excellent service and excellent landing

My flight was cancelled with no explanation after I had already cleared security. I was given 4 options to rebook, only one being non-stop like I had paid for. I grabbed it. It was 4 plus hours later and then took off even later. Biggest complaint is that I booked early and had an aisle seat. They gave me a "window" seat in front of the exit row, so the seat did not decline. I weigh all of 103 #s and it was tight for me! For what I paid, I feel I was kind of ripped off. I think they should have given me the empty comfort seat for the inconvenience. There was no apology nor any explanation as to why the flight was cancelled. My guess is it benefitted Delta in some way.

The flight was on time. I generally don’t drink or eat on short flights and the seats were good and the flight attendants were friendly. That’s all I expect

It was nice to have gotten up upgraded to first class with a meal on a three hour flight

Not great experience - we were super late boarding due to issues with aircraft. Then when we finally all got onboard and seated and they started taxiing out to the runway they just stopped then turned around and went back to the airport. Apparently the crew “ran out of time” to legally fly us. They mentioned that they were about 2 minutes away from taking off. I understand the rules and safety but kinda wonder why they would have bothered boarding us in the first place? Had to go all the way back and de plane and then wait in a HUGE line to get a hotel (this is somewhere around 2:30am) finally got to hotel by Uber (no shuttle after 20min so gave up) and they ended up putting us all back on the same aircraft at 10am next morning so got about 2.5 hours sleep. They did give us. $250 credit, but it was a São Paulo Brazil flight out of Dulles. The flight and everything was fine.

United overall experience is great these days. Airport experience was very organized. Staff on flight were great. App and information as good as it gets.

United have really come back. Airport and boarding process is clear and good, app and information also very good

They charged a fee for 1st bag checked. Others in same party were free.

Flight was delayed 8 times. We were sitting at the airport for 14 hours. We got 2 hours of sleep (if that) on what was not meant to be a red-eye.

The movies offered were great. Staff were very pleasant and very efficient.

After a delay at the gate, C3, at Ohare on Sunday, I left my Blk ski coat on the bench at the gate, lost! Please review my lob claim, thx.

Very bad! They kept delaying my flight and wouldn’t do anything about it

Nothing specific. Cabin temperature was too high for some reason.

It was just fine. I managed to make all my connection too sbut had trouble in Munich with no wheel chair and trouble trying to get help from the airport people to get to the other terminal for my flight. Finally a wonderful lady Amelia, helped me to make my flight connection Timon with zero time to spare.

Over 40 years ago my AC return flight was canceled, during this last summer the same thing happened. AC denied everything Canadian like paying for accommodations and basic necessities. So why would I ever want to fly AC again? This last flight my wife took the return flight had problems and left late, so I guess they are getting better. However I have no faith in this airline so I drove to this last destination! I'll never fly AC again!!!

Great check in process in LA and good service The check in process as well as at the gate is way better in the US versus canada 🇨🇦

Super experience. Earlier than schedule departure and arrival. Baggage handling was very good

Allow me to book extra bag check in as free though I packed in 1 luggage but that was 7 LBS overweight so make another bag to free check in.

I would like to get my money back. I flight was 4 hours late on the way to detroit, And same on my way back to Brussels they cancelled my flight and give me an other ticket and i had to wait 5 hours.

All attendents were very efficient, pleasant and happy. Everything went smoothly. The seats could have been wider. There could have been more free food instead of just one small bar.

My seat was one of those that couldn't recline, but the problem was that it was abnormally upright, so the headrest actually made the seat concave, which was uncomfortable and hard on my lower back. I had to ball my jacket up and use it as lumbar support. goodness I had it with me.

Boarding was so so after zone 3 was called all other zones went in

Ground staff and cabin crew were excellent. Flight was perfectly on time. Zero issues.

Even after a delay, getting off the ground, thanks for keeping me safe, the airline made certain that my connecting flight was rebooked to get me to my final destination. It was actually rebooked twice, and my luggage still managed to meet me. The airline gave me a credit for food and beverage to be used at the airport vendors, regretfully, the credit did not transfer to my final boarding pass. Oh, well…

Trip was smooth, good drew, average meal, almost cold coffee. Excellent landing. Did not enjoy going down the stairs, walking to the gate, walking up the stairs, going a long walk to the exchange gate, and going down the stairs again to be bussed all the way where we originally landed to take our next flight! Over all an average experience. Thank you.

I booked extra leg room, due to seat neighbor i now consider extra shoulder and arm room as well. Seems like the seats shrink in width now The crew was very friendly and professional ( 100%). Food was good not great, breakfast was bad, a dry slice of bread would have been better. Facilities clean.

Luggage transfer in Chicago was not performed in time. I received my luggage at my destination two days later.

love the crews and my only problem was the delay at Frankfurt was very bad. I have travelled with Lufthansa for over 30 years now and this was cost me some planned business appointment

The flight delay made the connection a bit tight but that's outside the flight crew's control.

We just made it to our connecting flight. A long, long speed walk!

We didn't get the coffee with breakfast in the morning.. 30 mins lazer I asked flight attendant why don't we get coffee now at least.. after the breakfast..she said that captain announced possible turbulences fee minutes ago, which didn't ecplain why we didn't get it with the breakfast..breakfast was very poor btw..just little pastry which you can eat in 4 little bites. Turbulences fortunately didn't even happen.. but we didn't get that more than necessary coffee in the morning after the night flight with very poor sleep.. They just served breakfast 1 hour afzer we took off..at like 11 PM.. that doesn't make sense at all.. Also, flight attendants weren't very nice..they looked like they're not happy with their job.. :/

Lufthansa still has a good level of quality compared to US airlines, especially with respect to (1) food quality - actually tasty, (2) good French red wine - free, (3) good movie selection. Also my ticket price includes 1 free check-in luggage, while some other budget airlines sneak in an extra $150 for a checkin.

Everything you need to know for your flight from St. Louis to Porto

Information on your arrival and departure airports