SEA - OPO

$252 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 8/28. 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
$654
Typical prices: $899-$1,192
Multiple Airlines
Wed 9/16Tue 9/22
SEA - OPO • 2 stops
Cheapest one-way
$252
Typical prices: $262-$853
Multiple Airlines
Fri 8/28
SEA - OPO • 2 stops
Top airlines
Cheapest • from $709 (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
Insights
Insights
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

Wed, Sep 16 - Tue, Sep 22
Multiple Airlines Logo
5:40 pm - 7:45 pm
SEA
-
OPO
18h 05m
2 stops
Multiple Airlines Logo
6:30 am - 3:40 pm
OPO
-
SEA
17h 10m
2 stops
$654Multiple Airlines
Wed, Sep 16 - Tue, Sep 22
Multiple Airlines Logo
5:40 pm - 7:45 pm
SEA
-
OPO
18h 05m
2 stops
Multiple Airlines Logo
10:00 pm - 3:40 pm
OPO
-
SEA
25h 40m
3 stops
$658Multiple Airlines
Wed, Sep 16 - Tue, Sep 22
Multiple Airlines Logo
5:40 pm - 8:00 am
SEA
-
OPO
30h 20m
3 stops
Multiple Airlines Logo
10:00 pm - 3:40 pm
OPO
-
SEA
25h 40m
3 stops
$692Multiple Airlines
Sat, Aug 22 - Fri, Sep 4
Scandinavian Airlines Logo
3:55 pm - 7:30 pm
SEA
-
OPO
19h 35m
1 stop
Scandinavian Airlines Logo
5:55 pm - 1:45 pm
OPO
-
SEA
27h 50m
1 stop
$709Scandinavian Airlines
Sat, Aug 22 - Fri, Sep 4
Scandinavian Airlines Logo
12:36 pm - 7:30 pm
SEA
-
OPO
22h 54m
2 stops
Scandinavian Airlines Logo
5:55 pm - 1:45 pm
OPO
-
SEA
27h 50m
1 stop
$769Scandinavian 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
$771Iberia
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
Mon, Nov 9 - Mon, Nov 23
Multiple Airlines Logo
10:35 am - 8:00 pm
SEA
-
OPO
25h 25m
2 stops
Multiple Airlines Logo
8:40 pm - 10:15 pm
OPO
-
SEA
33h 35m
2 stops
$781Multiple Airlines
Sun, Oct 18 - Mon, Oct 26
British Airways Logo
8:20 pm - 8:35 pm
SEA
-
OPO
16h 15m
1 stop
British Airways Logo
8:40 pm - 10:51 pm
OPO
-
SEA
33h 11m
2 stops
$787British Airways
Sun, Oct 18 - Mon, Oct 26
Iberia Logo
6:23 am - 11:45 am
SEA
-
OPO
21h 22m
2 stops
Iberia Logo
8:40 pm - 12:14 am
OPO
-
SEA
34h 34m
2 stops
$791Iberia
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$252
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 $252 for a one-way ticket and $709 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 $1,018 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 1532 reviews
8.4Crew
7.7Comfort
7.2Entertainment
7.8Boarding
7.3Food
Airline reviews

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

2.0 MediocreNewton, Mar 2026
IAD - AMS
Read more KLM reviews

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

They forgot to serve food and the crew was very unfriendly. Never experienced such a bad KLM flight. Usually fly from Toronto. New York was different.

Over 1 Hr delay. No APU so no AC on ground. Plane was hot during boarding and then they closed the doors over 20 minutes before engine start so interior of plane was steamy hot and stuffy. Could have been helped by opening doors until ready to depart.

My flight was delayed by 6 hours then I missed BOTH of my connecting flights, I then had to stay in the AIRPORT at JFK because soooooo many people also suffered from missing flights and there was no hotels available. I would like to be compensated for this experience! I had to stay in the airport for over 16 hours!

Cabin crew were excellent, very proffesional, polite and friendly, in flight snack was underwhelming, a packet of cheese biscuits, im sure KLM could run to a sandwich!

Overall very positive. Boarding was quick and organized. Cabin was clean and seats were reasonably comfortable. Cabin crew was excellent and the meals provided were also of good quality

This fight left ahead of time which meant it arrived early which was great. Staff were very professional, but as with all these Short hop Flights the food was a disappointing snack There was no entertainment on this flight, but I did not expect any

Transfer at CDG to connecting KLM flight to Amsterdam was a NIGHTMARE. LONG WALKWAYS, NO MOVING WALKWAYS, POOR signage, Have to take a train & No staff visible to help navigate the maze. AVOID TRANSFER AT CDG AT ALL COST.

Seats were comfortable crew members support was very good but AVML ordered or selected by us needs a lot of improvement.

The IFE was quite old, but it worked fine and the content was good. The cabin crew were excellent and the food was as also very good

My flight was delayed by 4 hours in 30 minute increments. The gate agents were amazing but the communication was not. We were told that there was a maintenance issue but they didn't know what it was. That didn't inspire confidence. Then they said they found it and it was fixed and the pilot just needed to sign off. Then the pilot needed to talk to the other pilot from the arriving flight and we'd be fine. Then we were waiting for the pilot to call back. Then the maintenance issue wasn't fixed. Then they decided we were getting a new plane (why didn't they decide this earlier??). Fine. But then they announced we were changing gates AND terminals. And we were boarding in 20 minutes. So we all had to run to the new terminal gate. We could have taken off at that time, but we then had to wait for all the people who rebooked on a different flight to book this flight again. That took 30+ minutes because there was only one gate agent. When everyone ditched this flight, I saw it as an opportunity to upgrade to comfort. Delta, the greedy jerks they are, charged me $121. After their delay, their fault, their issues, couldn't even discount an upgrade. They only handed out $12 meal vouchers for the delay. I can't even get a snack from starbucks for that.

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.

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

The Boarding process was great. Particularly since my wife and I require assistance. The flight attendants were amazing. We travel frequently; they honestly were a cut above. 😀

Crew was nice, meal was good. Entertainment had to be rebooted 3 times and still did not work. Turns out there was residue on screen, it needed to be cleaned to prevent the touchscreen buttons from continuously activating. I had entertainment for the last 45 minutes of a 5 hour 45 minute flight. Really unacceptable for first class. Flight attendent indicated your cleaning solution creates this problem. Seems as if this is widely known, you should be using a different product or cleaning better. Really really disappointing which simply added to the wi fi on your planes with reliably never ever works.

Snacks and included beverages were appreciated. Boarding went smoothly. Plenty of overhead bin space. Seats get very uncomfortable after a couple of hours. After waiting 10 painful minutes for my walker, a very nice Delta guest agent pushed me in a wheelchair to the gate. It was finally delivered to me after another 15 minutes . Our checked bag was on the carousel long b4 I was able to retrieve it. Fortunately it was still there but somewhere along the way the straps we used to secure it were removed and and were not reattached. Wish I had made note of the agents name.

The cabin temperature was nice and cool. The wifi was not working.

Could not get my connecting flight boarding pass until four hrs before departure! Ver annoying especially since the staff could not explain why!

First flight out and was 85 minutes delayed. Notification came out way too late

Was forced to check in my small carry on, even though I informed the crew it has very fragile items inside

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

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 :)

It was a great experience. The only thing I would have changed was that the bathrooms were never cleaned and they got very dirty.

It was an OK flight with below mediocre service by their flight attendants

Wasted a lot of time trying to find the CDG lounge - it was not next to the connecting flight gate like the Air France staff said.

The only reason the overall rating wasn't "excellent" was due to problems in claiming luggage. The bags are delivered to the main area (Cinta 35) for domestic passengers, but to a DIFFERENT ROOM for international arrivees. After waiting 30 minutes, someone (who didn't appear to be from Air France or the airport) told us to go to another area. There we found our bags, which appeared to have been awaiting us for a while. We had to go through a bag check before leaving the airport. If we had been alerted to this possibility, or better yet, been to go directly to Cinta 34, we could have eliminated quite a bit of waiting.

I did not get my baggage at my final destination..poor coordination with connecting flights with partner airlines (Saudi airways). Also the food was very mediocre.

Not great , just ok . I expected better food but it did not deliver . Flight staff was ok . The guy at the drop off bag counter was the only saving grace in this whole trip . He was pleasant, friendly and very helpful . You couldn’t ask for a better assistance from him .

We transited through Chad and what was supposed to be a 1hr 20 minutes transit time lasted over 4hrs. We didn't get regular updates until we complained. After a 10hr flight from Paris no form of refreshment given and finally arrived Abuja over 6hrs later and none of my bags came

Our flight was delayed several Times due to mechanical issues. Although I understand this may happen at times, it was very inconvenient and we had to book a hotel for an overnight stay. We were traveling with my 3-yo grandson and waiting at the airport from noon until 6:30pm with no reassurance that our next rescheduled flight would depart, we had to decide what’s best for him. A day later, I found out that I may be able to demand compensation if my flight is delayed more than 4 hours. I will hav to read the fine print next time.

Very comfortable seating and the Flight staff were very attentive. The premium economy section that I was seated in was very clean, updated, and well appointed. I would highly recommend flying United Airlines as this experience was better than the Japan Airlines business class that I flew several months ago.

United needs to step up their game. Delayed flight leaving Seattle, San Francisco. Older aircraft, not very comfortable.

Food was poorly timed and not good.. Hand held snacks, really. I kept asking for water and never got any. Service was rushed for a 7-hour flight.

Had to cancel first flight because Airporter Bus took over 3 hrs to get to airport which resulted in an extra $378 dollar fare . Is there anyway I can be reimbursed for initial fare since it was not my fault? Sent from my iPhone EJ Ledet

Delayed by 2.5hrs any longer and they would’ve had to honour their own policy for breaking their own rules and regs. Not cool, especially when I have an infant child that needs to stay on a routine and they get schedules.

They had three choices for snacks - but you could only have one - and they ran out of the dark chocolate before they made it all the way down the aisle... Packed flight - limited service.

They opened my checked bag and even though my lock was tsa approved, they loose my lock and left my bag just like that. Incompetent people, very upset about it. I’ll try to avoid traveling with united

We fly to Ecuador frequently. Checking in is usually a hassle because most United agents take some time before they can verify that my passport doesn't require a visa to Ecuador. This time the process was even longer due to the cyber attack. But she was really nice to us. So glad we brought plenty of snacks to supplement the 3 flights from SEA to GYE.

We had selected seats in the app that were a 2x2 format in the middle of the plane. Our seats when we got on the plane had been moved to the back rows in a 3x1 format. What’s the point of paying up for tickets that allow seat selection if the airline will just change them?

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

It would have been nice if my luggage had made it onto my connecting flight as well. Now I have to wait for my luggage to be delivered and that might take a while, which certainly put a damper on the entire experience.

Biggest gripes were that the seats were extra narrow as the 4-in-the-middle taper down. As with most flight, too little leg room hurts my aging hips. Also changing the flight time to 3 hours earlier meant that we had a terribly long lay-over in one of the world's most boring airports

German crew were very kind. Food was okay but can be better, especially bread was not good, Garbage collection was very poor.

Great! Great staff, great food, great flight :) Keep up the good work!!!

It was good. Nice entertainment selection to keep me busy for the timeframe I wasn't sleeping. Professional, courteous and attentive crew.

They lost my bags and I didn't get them for 4 days after. This also happened to about 30 other people on my flight from fra to MAA (I know bc we were all filing claims in line together from the same flight.)

Flight took off arrive Frankfurt fine ... and then the Pilot parked the plane for 20 minutes while waiting for a steps vehicle to arrive so we all could deplane. This caused us to miss our Naples flight by 6 minutes while running to the next gate.. We are aware of 3 others who also miss their flight. Lufthansa Support said "why miss your flight, your flight arrived on time?" We explained, they provided another flight many hrs later, no meal voucher because our "flight was ontime".

They help we received from the check in crew and boarding cr

Both flights were on time. Great selection of movies on board. My luggage didn't get lost, which made my trip very easy.

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

Information on your arrival and departure airports