SEA - OPO

$258 Find Cheap Flights from Seattle to Porto - Compare and Save

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Seattle to Porto departing on 8/31. 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 Seattle to Porto.
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Seattle to Porto.
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Everything you should know

Cheapest round-trip
$690
Typical prices: $889-$1,192
Multiple Airlines
Sat 9/5Sat 9/12
SEA - OPO • 3 stops
Cheapest one-way
$258
Typical prices: $402-$741
Multiple Airlines
Mon 8/31
SEA - OPO • 3 stops
Top airlines
Cheapest • from $757 (round-trip)
Best reviews • 7.8 score
Airline reviews
Airline reviews
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Airline reviews
Airline reviews
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Nonstop flights
Not available
There are currently no direct flights between Seattle and Porto. You'll need at least 1 connection.
Insights
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Top layover airports
Cheapest • Avg $807 (round-trip)
Shortest trip • 14h 52m (one-way)
Insights
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When to book
in advance
Our data shows that travelers who book at least 2 weeks in advance save around 27% compared to booking last minute.
Insights
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Insights
When to travel
Cheapest • 45% price drop
Most popular
Good to know
Good to know
+1
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Flight Deals
Booking Insights
Flight Deals

Cheap Flights from Seattle to Porto (SEA-OPO)

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Seattle 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 Seattle to Porto

Sat, Sep 5 - Sat, Sep 12
Multiple Airlines Logo
8:00 am - 12:40 am
SEA
-
OPO
32h 40m
3 stops
Multiple Airlines Logo
7:10 pm - 6:32 pm
OPO
-
SEA
31h 22m
3 stops
$690Multiple Airlines
Sun, Oct 11 - Wed, Oct 21
Multiple Airlines Logo
5:40 pm - 9:20 pm
SEA
-
OPO
19h 40m
2 stops
Multiple Airlines Logo
10:00 pm - 4:00 pm
OPO
-
SEA
26h 00m
2 stops
$720Multiple Airlines
Wed, Aug 19 - Wed, Aug 26
Multiple Airlines Logo
7:00 pm - 12:40 am
SEA
-
OPO
21h 40m
3 stops
Multiple Airlines Logo
10:45 am - 8:40 pm
OPO
-
SEA
17h 55m
2 stops
$722Multiple Airlines
Tue, Sep 8 - Tue, Sep 22
Multiple Airlines Logo
7:00 pm - 10:55 pm
SEA
-
OPO
19h 55m
2 stops
Multiple Airlines Logo
6:15 am - 6:45 pm
OPO
-
SEA
44h 30m
3 stops
$734Multiple Airlines
Tue, Nov 10 - Mon, Nov 16
American Airlines Logo
5:24 am - 7:40 am
SEA
-
OPO
18h 16m
2 stops
American Airlines Logo
8:40 pm - 9:45 am
OPO
-
SEA
21h 05m
2 stops
$757American Airlines
Wed, Nov 11 - Tue, Nov 17
British Airways Logo
6:50 pm - 5:50 pm
SEA
-
OPO
15h 00m
1 stop
British Airways Logo
8:40 pm - 10:15 pm
OPO
-
SEA
33h 35m
2 stops
$759British Airways
Sun, Sep 13 - Thu, Sep 24
Multiple Airlines Logo
3:40 pm - 11:35 pm
SEA
-
OPO
23h 55m
2 stops
Multiple Airlines Logo
7:00 am - 9:40 am
OPO
-
SEA
34h 40m
3 stops
$762Multiple Airlines
Sun, Aug 23 - Mon, Sep 21
Multiple Airlines Logo
3:40 pm - 9:40 am
SEA
-
OPO
34h 00m
3 stops
Multiple Airlines Logo
10:40 pm - 9:04 pm
OPO
-
SEA
30h 24m
3 stops
$770Multiple Airlines
Mon, Nov 9 - Mon, Nov 23
Iberia Logo
6:50 pm - 8:00 pm
SEA
-
OPO
17h 10m
2 stops
Iberia Logo
9:55 pm - 4:55 pm
OPO
-
SEA
27h 00m
2 stops
$772Iberia
Tue, Nov 3 - Tue, Nov 10
Iberia Logo
5:24 am - 7:40 am
SEA
-
OPO
18h 16m
2 stops
Iberia Logo
8:40 pm - 9:18 pm
OPO
-
SEA
32h 38m
2 stops
$775Iberia
Booking Insights

KAYAK's insights & trends for Seattle to Porto flights

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

How much is a round-trip flight from Seattle to Porto?

This analysis is based on the cheapest round-trip price found on KAYAK in the last 12 months by searching for a flight from Seattle to Porto departing in September.

What is the cheapest month to fly from Seattle to Porto?

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Seattle to Porto, removes the top 0.1% to account for outliers, and then takes the median of all values for each month.

The cheapest month for flights from Seattle to Porto is January, where tickets cost $498 (return) on average. On the other hand, the most expensive months are December and August, where the average cost of round-trip tickets is $1,466 and $1,092 respectively.

How far in advance should I book a flight from Seattle to Porto?

To calculate weekly average prices, KAYAK takes all prices for each week before departure over the last year for round-trip flights from Seattle to Porto, removes the top 0.1% to account for outliers, and then takes the average of all the values for each week.

To get a below average price on the flight from Seattle to Porto, you should book around 2 weeks before departure, which saves you about 27% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 3 weeks before departure.

Good to know

Low seasonJanuary
Cheapest flight$258
Best time to beat the crowds with an average 45% drop in price.
Most popular time to fly with an average 13% increase in price.
Flight from Seattle to Porto

When to book flights from Seattle to Porto

Are your dates flexible? Find out the best times to travel from Seattle 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 Seattle to Porto

  • Do I need to get a visa before this flight?

    Traveling to Portugal for a stay in the Schengen area is hassle-free if your trip is for under 90 days within a 180-day timeframe. No visa is required for this duration. Keep in mind that a new 180-day period starts after spending 90 consecutive days outside the Schengen area. This allows you to enjoy your stay in Portugal without worrying about obtaining a visa.

  • What are some reasons to consider upgrading to First Class on Delta Air Lines?

    Enjoy the comfort of wider and more spacious seats and the added convenience of ticket flexibility without change fees. With Sky Priority service, your journey will be well-crafted from the beginning to the end. Indulge in a travel experience like no other, making your trip truly unforgettable in First Class.

  • What is a good choice for a sustainable airline on this trip?

    United Airlines is deeply dedicated to operating as an environmentally sustainable and responsible airline, with this commitment deeply embedded in its strategy and core principles. By the year 2050, the airline strives to achieve a remarkable goal of completely eliminating 100% of its greenhouse gas (GHG) emissions, going beyond the conventional reliance on carbon offsets. As part of its mid-term objective, United aims to reduce its carbon intensity by an impressive 50% by the year 2035, comparing against the levels recorded in 2019.

  • If I have special dietary needs, what is a good airline choice?

    On KLM, you have the convenience of ordering a customized meal that caters to your specific dietary needs. They offer various options, including low-fat, low-salt, meals suitable for diabetic, gluten-intolerance, or lactose-intolerance diets. Additionally, there is a limited number of vegetarian meals available on each flight. To ensure you receive your preferred vegetarian or vegan meal, it is advisable to place your order at least 24 h before your scheduled departure.

  • What is the cheapest flight from Seattle to Porto?

    In the last 5 days, the lowest price for a flight from Seattle to Porto was $258 for a one-way ticket and $690 for a round-trip.

  • Do I need a passport to fly between Seattle and Porto?

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

  • Which aircraft models fly most regularly from Seattle to Porto?

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

  • Which airline alliances offer flights from Seattle to Porto?

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

  • Which is the best airline for flights from Seattle to Porto, Delta or KLM?

    The two airlines most popular with KAYAK users for flights from Seattle to Porto are Delta and KLM. With an average price for the route of $1,021 and an overall rating of 7.8, Delta is the most popular choice. KLM is also a great choice for the route, with an average price of $952 and an overall rating of 7.8.

  • How does KAYAK find such low prices on flights from Seattle 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 Seattle to Porto.

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

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to Porto from Seattle 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 Seattle 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 Seattle with another airline. Booking your flights between Seattle 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 Seattle 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 Seattle up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

KAYAK’s top tips for finding a cheap flight from Seattle to Porto

  • If you would like a way to Seattle Tacoma International Airport (SEA) that does not involve driving yourself, check out the 1-Line from Sound Transit that riders can take from Pioneer Square Station to the airport in about 33 minutes.
  • Because there are no direct flights available on this trip, some layover airports you can expect to use include Amsterdam Airport Schiphol (AMS), San Francisco International Airport (SFO), and Zurich Airport (ZRH).
  • When you fly with WestJet, carry-in bags can be no bigger than 21 x 9 x 15 inches, and a personal item can be no larger than 16 x 16 x 13 inches. There is no weight limit for either bag.
  • Before checking bags on Air France flights, make sure bags don't exceed linear dimensions greater than 62.2 inches, including wheels, pockets, and handles. The weight allowance for Economy Classes is a maximum of 50 lb, while Business and La Premiere Classes allow up to 70 lb.
  • When flying with American Airlines, you are permitted to bring one golf bag containing golf clubs, golf balls, golf tees, and one pair of golf shoes. It's essential to be aware that standard checked bag fees, which vary depending on your destination, will apply to bags weighing up to 50 lb and measuring up to 126 inches in total dimensions.

Reviews of the top 5 airlines serving from Seattle to Porto

 
See real verified KAYAK customer reviews for airlines flying from Seattle 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 Seattle 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.
7.8
KLMOverall score based on 1530 reviews
7.7Comfort
7.3Food
8.4Crew
7.8Boarding
7.2Entertainment
Airline reviews

The flight was 45 mins late leaving, we sat without a/c for some of this, 2nd Meal was a slice of pizza. Movies were good.

8.0 ExcellentAnonymous, Jun 2026
LHR - AMS
Read more KLM reviews

The flight was 45 mins late leaving, we sat without a/c for some of this, 2nd Meal was a slice of pizza. Movies were good.

As always, it’s a pleasure to travel with KLM. It is one of my favorite airlines.

Outstanding even though the 330 was one of the oldest in the fleet. The difference was the attentiveness and responsiveness of a really experienced flight attendant. For airline food great variety of interesting choices and good tastes supported by a good wine selection.

Brand new plane lots of room the snack was very flavourful and enjoyable

As per usual when you Hit the UK it's a slow process through customs Not as efficient at Thailand for sure

There were no charge points for phones on the economy seats. The seats were comfortable overall. Food was okay.. flight was on time

The flight was delayed. The aircraft was unclean. Promised seat was not given due to change in Aircraft. Not one crew on ground was in a position to give any response. Amsterdam Airport is AVIODABLE Over crowded. Over Expensive. Poor Services.

The crew were unprofessional with a racist element. I was physically abused as well from one of the crew members

Empty seats next to me - wish it had been for a longer flight!!

I’m grateful for the KLM Air France shuttle bus service to Ottawa. However due to construction and other issues related to the chaotic Uber pickup system at YUL, it’s a challenge to find the Kelios bus service to Ottawa. The signs are not clear or even available. No staff to guide passengers. It’s a stressful experience.

Not really a “Delta” problem but worth mentioning: Boarding was a difficult process. TSA seemed understaffed and Pre-Check took longer than regular TSA. The supervisor was frazzled and yelled at travelers. Once through TSA, we had to put our carry-ons through another x-ray machine. Then queue up to board with both boarding pass and ID. Then, when we got to the stairs on the tarmac, we had to show our boarding pass again. Maybe this is just normal for Kona since the terminal is outdoors (but still a “secured” area).

flight was delayed 4+ hours. there was really no understanding of why? weather? the last hour of delay was post boarding. pilot seat was broken. was that the real reason? nonetheless, long day of inconveniences.

Love me some Delta. One of the few airlines to recognize and support veterans. Easy boarding, flight was on time and arrived early and the flight attendants were excellent on this flight.

I thought the service was very nice and pleasant. There were no hiccups and no issues so overall a good experience.

Very good flight. Crew was great. No issues and we even arrived early.

The flights are constantly late anymore, and they won't even give you a glass of water on the plane. For years, they were able to do a service on this flight from Atlanta to Knoxville and Knoxville Atlanta now they say it's too short of a flight. You can't even get a quick drink of water.

Flight got canceled 4 times, missed my connecting flight due to delays, have to wait to go home tomorrow

Third flight in two months where the crew was not there. Comfort seating does not guarantee overhead bin space. Passengers with children are allowed on the plane first - if you are flying to and from Orlando, this means half the plane has boarded before you get on. And somehow all the bin space is taken up. 3 out of 5 flights have had issues with equipment or procedure. Some of these instances caused the flight to be delayed because of a "nuisance" light. One time it was a bag that had been brought on board but did not belong to anyone so we had to return to the gate. Last night we were told the "AC" on the plane doesn't work well and we're 10th for take off- because the crew was late - and that it will get cool when we're in the air. Not sure if this is usual, but I didn't think flight crew could jump seat in first class. Movie and TV selection has not been refreshed for several months- flying one to two round trips each month easily exhausts the list of content.

Great experience nice pilot very soft and easy landing and take off

We sat on the runway for over an hour before departure. That was unwelcome.

Seats! The eternal problem in economy. They are like stones!!

I love Air France. This was another great experience despite a slight delay in the departure. The time was made up on flight. I would take AirFrance again when traveling to the far East. Merci beaucoup.

Everything is good except the seats are tightened no rooms for the legs,

The plane's pilots, including the captain himself, thanked me for the flight. I know it's just marketing, but it was really nice to see these people. It's a great idea. Airplane food is never "good," but the entire crew and flight organization were top-notch. I really liked Delta, and I think I've traveled all over the world, and that was something new for me. Maybe even the old planes, the B767, but next time I have a choice, Delta will be my first choice. Thank you, a satisfied passenger :)

Middle seats SUCK!!!! I paid more money than I should have because of your terrible site Kayak.com. I'll try to use your competitors going forward. I am so disappointed you would play off business class.com as business class seats

They lost my bag and I still haven’t received it yet

Not consistent with the food quality (I mean taste not freshness)

Safe and stable made me sleepy and I slept and dreamt 😂😂😂😂

I don’t like that an equipment change caused my seat to change from 23A to 44A. The boarding was also delayed. The crew were excellent, however and very attentive. The food was not bad.

Worst airlines either. First leg was delayed because of crew not available. My connection was missed so they booked me automatically the next day! But, impossible to get anyone on site, web site does not let me access my reservation anymore, confirmed by useless agents over the phone. My 2-leg trip with part in business class arriving at 4:10pm ends up in an awful 3-leg arriving at 9pm the next day with no way to even choose the seats and of course at the very end of the plane. I can understand problems arrive but the way Air France handle it is just unacceptable. You are on your own. Apparently getting you to your destination is the only thing they consider their duty. The customer experience and fatigue is none of their concern. And I have a status with them. I will reconsider my priorities when flying with Air France and encourage everyone to do the same.

Awful. Delayed flights, missed connection to Toronto. Hotel vouchers were for already booked hotels x3. Giant waste of my time

Horrible I am at almost 2,000,000 miles on United. This was probably the worst flight ever. An hour and a half before takeoff I get a message that they’re changing the plane and I no longer have a seat in Polaris business Supposedly, there was a problem with the plane, but then there was no other plane Finally, they decided to bring a plane from Newark to Washington Dulles Of course the original flight was at 10:45 PM so by the time the plane got there it was 12:30 AM. It had not been cleaned. It had not been catered. They don’t really have people available to do those things when it’s not pre-programmed at 1 o’clock in the morning. The crew had to be changed And the new plane held 28 fewer people than the scheduled plane There is no way you can hate United Airlines enough The people at the gate were actually just fine, but it was management who was completely useless And did they send extra help to the people at the gate? Did they send supervisors? Of course not. Just don’t take United find somebody else or buy a boat

Great experience. Boarding was fast, staff were very nice and funny, everything at the seat worked well.

Boarding was great, and the crew were very friendly. The seats must have been a bit on the older side and you could feel some of the seat components through the padding. Also, the plugs did not work on the row's entertainment screen or charging ports. Checked bag was transferred for connecting flight, and we appreciated how early we had the connecting gate information.

Lost one piece of luggage even though I checked in 2.5 hours before the flight

It was Swiss. Our kosher meals were literally frozen solid and therefore inedible, and the crew didnt care.

For the expense of first class, the seats could have been nicer and higher tier snacks would have been nice.

The boarding process on the departure from LA was rather slow even though I was in Group 1. For first class, I was not expecting to have to pay for Wi-fi but I did and then the wi-fi was spotty. The entree was surprisingly good and so that was a pleasant surprise. However, once I got to Houston, it was terrible. Unfortunately there was bad weather but the constant gate changes for my connecting flight was difficult to manage due to having to navigate back and forth between different terminals.

We used Kayak to reserve our tickets and specifically checked the luggage option which was a more expensive option. When we arrived at the terminal we had to pay an extra $90 per suitcase for the three passengers. This has been a pattern for the past 3 years. Why charge for a more expensive luggage option, and the ticket price not include luggage?

They delayed the flight 3 hours because it wasn't full they moved us to 5 different gates probably the worst airline ever not even spirit is this bad.

The flight was cancelled, so why are you asking me how the flight was?

We sat in our seats on the tarmac for almost 3 hours due to storms. They would not give us water or a snack. We were to depart at 7.30 pm and it was about 10.30 when we took off. No dinner until much after that. Beef type noodle dish was terrible with about a teaspoon of beef in it. The breakfast sweet waffle with egg and sausage inside was horrible. An English muffin sandwich would have been much better. Food was the worst in all of our years of traveling the world.

Our screen kept turning off ...3 times...had to get crew attention to turn it on again

They messed up my seat so I didn’t get the one I paid for

Put me on standby; flight was late; missed my connecting flight; disaster

Flight attendants were fine, seats a bit hard but I use a cushion for extra support. The only issue was it was a bit too cool and I needed to ask for and received and extra blanket. I survived!!!

Very few things and/or people are excellent. It was very good.

Extremely uncomfortable seats. Experience was like a Frontier Airlines flight. Would not fly it again.

Very, very tight legroom. They must’ve jammed in an additional few rows of seat seating. Denver to Munich was the least legroom I’ve ever had on any flight, let alone a multi hour international journey. I will not take that flight again.

In my first flight with Air Canada we sat in the plane for 4:00pm to 6:30pm. Finally we were asked to get off the plane and we were told the flight was cancelled after 7:00pm There was o clear explanation of what was the problem. I was booked without my permission on a Delta Flight at 7:30pm that was leaving at 8:00pm and I still had to go get my luggage(my final destination was Rome with one stop in Toronto. The luggage claim for Canada was closed so had to return to finally get it on the luggage belt.. Of course I missed the Delta flight and all the next day flights were booked. I also lost what I paid for my stay in Rome because I did nt cancel in time. A complete nightmare.

Everything you need to know for your flight from Seattle to Porto

Information on your arrival and departure airports