SEA - OPO

$251 Find Cheap Flights from Seattle 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 Seattle to Porto departing on 4/24. 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, 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 Seattle to Porto, as well as popular online travel agencies
Travelers love KAYAK
41,299,237 searches in the past 7 days on KAYAK

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Everything you should know

Cheapest round-trip
$625
Overall average: $1,010
United Airlines
Tue 8/18Thu 8/27
SEA - OPO • 1 stop
Cheapest one-way
$251
Typical prices: $501-$629
Multiple Airlines
Fri 4/24
SEA - OPO • 3 stops
Top airlines
Cheapest • from $625 (round-trip)
Best reviews • 7.9 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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Insights
Top layover airports
Cheapest • Avg $834 (round-trip)
Shortest trip • 13h 39m (one-way)
Insights
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Insights
When to book
in advance
Our data shows that travelers who book at least 3 weeks in advance save around 30% compared to booking last minute.
Insights
Insights
Insights
Insights
When to travel
Cheapest • 43% price drop
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
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KAYAK searches 100s of sites at once to find you the best travel deals.
We hope you love your trip to Porto!
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

Tue, Aug 18 - Thu, Aug 27
United Airlines Logo
7:30 am - 6:55 am
SEA
-
OPO
15h 25m
1 stop
United Airlines Logo
11:50 am - 9:21 pm
OPO
-
SEA
41h 31m
3 stops
$625United Airlines
Mon, Aug 10 - Tue, Aug 25
United Airlines Logo
10:40 pm - 7:00 am
SEA
-
OPO
24h 20m
2 stops
United Airlines Logo
12:15 pm - 3:36 pm
OPO
-
SEA
35h 21m
2 stops
$628United Airlines
Sat, Aug 8 - Tue, Aug 25
United Airlines Logo
11:49 pm - 6:55 am
SEA
-
OPO
23h 06m
2 stops
United Airlines Logo
12:15 pm - 6:59 pm
OPO
-
SEA
38h 44m
2 stops
$629United Airlines
Sun, Aug 9 - Tue, Aug 25
Air Canada Logo
7:20 pm - 7:00 am
SEA
-
OPO
27h 40m
2 stops
Air Canada Logo
12:15 pm - 10:28 pm
OPO
-
SEA
18h 13m
2 stops
$637Air Canada
Tue, Aug 18 - Thu, Aug 27
United Airlines Logo
7:30 am - 6:55 am
SEA
-
OPO
15h 25m
1 stop
United Airlines Logo
9:00 am - 6:15 pm
OPO
-
SEA
17h 15m
1 stop
$645United Airlines
Mon, Aug 10 - Tue, Aug 25
United Airlines Logo
10:40 pm - 7:00 am
SEA
-
OPO
24h 20m
2 stops
United Airlines Logo
12:15 pm - 7:07 pm
OPO
-
SEA
38h 52m
3 stops
$662United Airlines
Sun, May 3 - Tue, May 26
Turkish Airlines Logo
7:10 pm - 9:40 am
SEA
-
OPO
30h 30m
1 stop
Turkish Airlines Logo
4:50 pm - 5:15 pm
OPO
-
SEA
32h 25m
1 stop
$671Turkish Airlines
Tue, Aug 18 - Wed, Aug 26
British Airways Logo
1:30 pm - 7:30 pm
SEA
-
OPO
22h 00m
1 stop
British Airways Logo
12:25 pm - 12:54 am
OPO
-
SEA
20h 29m
2 stops
$674British Airways
Tue, Aug 18 - Tue, Sep 8
United Airlines Logo
7:30 am - 6:55 am
SEA
-
OPO
15h 25m
1 stop
United Airlines Logo
12:15 pm - 9:21 pm
OPO
-
SEA
41h 06m
3 stops
$675United Airlines
Mon, Aug 10 - Tue, Aug 25
United Airlines Logo
11:20 pm - 7:00 am
SEA
-
OPO
23h 40m
2 stops
United Airlines Logo
12:15 pm - 3:36 pm
OPO
-
SEA
35h 21m
2 stops
$678United Airlines
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.

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 September, where the average cost of round-trip tickets is $1,436 and $1,029 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 3 weeks before departure, which saves you about 30% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 5 weeks before departure.

Good to know

Low seasonJanuary
Cheapest flight$251
Best time to beat the crowds with an average 44% drop in price.
Most popular time to fly with an average 17% 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 3 days, the lowest price for a flight from Seattle to Porto was $251 for a one-way ticket and $625 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 $879 and an overall rating of 7.9, Delta is the most popular choice. KLM is also a great choice for the route, with an average price of $918 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.
7.9
DeltaOverall score based on 8277 reviews
7.8Entertainment
8.5Crew
7.9Comfort
7.2Food
8.1Boarding
Airline reviews

Love delta smaller commuter plane so no entertainment and paid wifi on MKE-LGA leg was extremely unreliable and slow

8.0 ExcellentMary, Mar 2026
LGA - MKE
Read more Delta reviews

Love delta smaller commuter plane so no entertainment and paid wifi on MKE-LGA leg was extremely unreliable and slow

Stop changing gates. Stop cancelling flights Stop moving my seat.

Extremely disappointed with Delta. They canceled flight last minute and then I rebooked the other flights and with which were delayed as well

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

The flight was flying with 30% capacity. The flight my seat from preferred seating to back of the seat. Even though i can understand that this was to balance the flight weight. The flight attendance decided to do the serving near my seat and in the middle , their noices woke me up from sleep , when i realized that the service has ended and when they were going back asked for a coffee, for which they answered they have completed teh service in my location. That really upset me as they woke me up and also rejected the coffee i asked. I ended up landing with a headache, thanks to the crew that screwed up my travel

Delayed. Hot. Passenger next to me was so large I couldn’t move.

Same experience as the flight from Norfolk to Atlanta where people are boarded in zones that don't make sense. People behind you on the plane will get on before you and they take the luggage space on your row.

The boarding process doesn't make sense since some people that will sit behind your rows are boarded before you and then they take up the luggage space above your head. I then have to wait for people to get off the plane before I can go back to get my luggage.

Good flight. Connector flight was delayed so made a short turnaround in Atlanta which was stressful. Otherwise, great crew, Staff in ATL was very informative about the delay and ensured people their connections were fine. Notified the ones that were not. Great communication.

The flight went very well, but the flight attendants didn't serve and food or drinks other than 1st class due to rough air but to be honest it wasn't that bumpy and I felt that they could've at least offered water and coffee perhaps. Also serving 1st class only is a bad look. I've been in 1st class many times and I would've felt that if the turbulence was too rough for the main cabin, it would be too rough for 1st class too.

It was really nice journey i personally recommend klm flight

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.

At the airport, terrible, I do not want to even remember it. It was too humiliating for a business class passenger.

Flight was ok but lack of communication cost me to literally beg to be put on another flight as connecting flight had departed

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.

Couldn’t get boarding pass in SLC even with help from a redcoat, so had to find a desk in AMS to get boarding pass. Technical problems so not sure why. Very inconvenient. The KLM app is not as user friendly as most apps. Also had to wait almost an hour on the tarmac for a fuel truck, which caused us to miss a connecting bus in LUX.

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.

First of all we couldn’t check in online, then we learn at the airport we were on stand by for KLM’s mistake of overbooking. The seats were not comfy at all. Our luggage got lost.

The travel company that you have on your site did me so wrong. I don’t know how it happened, but they put my son‘s name on my plane ticket flying to Vietnam. Along with his birthday. They would not have let me fly from Fort Myers to Ho Chi Minh City. I don’t think that I can ever use your service again. I typed my information into the browser along with my passport number and four days before I’m leaving I have to quickly search another ticket to fly out here.

Seats are uncomfortable. This has been a trend in the industry for decades. Trying to fit more seats on each plane to increase profits at the expense of the passenger.

The flight was delayed so we were dead tired, and after that the turbulence was horrible. I was very scared.

It’s always a great time flying with united airlines.

Good flight. Efficient boarding and competent flight crew. No problems until we arrived at our destination gate. We were early so there was an aircraft at the gate that had to move before we could pull in. Then, due to the type of aircraft we flew, the cabin door could not be opened until some luggage from the cargo bay was offloaded to preserve center of gravity characteristics. So, that further delayed deplaning. Despite being 20 minutes early on landing, we ended up being 5 to 10 minutes late after all the delays.

Everything went well except the turbulence what no one have a control of but pilot and crew handled very good!

There was no WiFi available, there were mechanical problems with the plane and we landed at C 124, then the gate was switched to A 26, then all the way back to C126! For a 75 yo woman traveling alone, this was a difficult journey, indeed!

This trip did not start off well. The inbound flight was delayed about 20 minutes. Then, after initial onboarding, the passengers had to deplane due to a mechanical problem. That took about 30 minutes to fix and be cleared. Then, reboarding was chaotic. It took a long time to sort passengers and two passengers on standby were ticketed but there was no seat. So, they had to deplane. One of the flight crew was trying to help passengers figure out a place to put their carry-on bags and that took more time. In the end, our scheduled 10:30 am departure did not actually take off until about 12:05 pm CST. The flight itself was long but we got to Houston. Some passengers missed their connecting flights and had to rebook. Not the best of flights I've had.

Staff were good. My seat was in need of repair, but for a short flight was not problematic. Usual basic snack and drink setup that you'll find on any US carrier. Over, a decent, basic flight.

Complimentary light meal would be appreciated. But great flight crew service on all legs

Departed Palm Springs over an hour late because there’s only one gate, and it has always delayed by the arriving and departing flight to Toronto and the arriving flight from Vancouver.

I checked a bag and there was only one agent to assist all customers with any issues.

I want to thank Carlos at the Miami AC desk - he was amazing and went over and above to help us out. Thank you Carlos and all the best to you!!! You made our faith in AC feel great! Sincerely, David Cubitt

Flight was canceled due to mechanical issues. After a considerable wait in the queue, Air Canada customer service was very helpful to get us on another flight. I am disappointed to report our rescheduled flight is for three days from now. Three days of extra expenses and inconvenience is unacceptable.

Extremely disappointing. My original Denver–Vancouver–Bangkok itinerary was cancelled due to a crewing issue. I was not proactively supported and had to drive back home after already reaching the airport. Communication was poor throughout, and attempts to contact customer service resulted in being on hold for nearly three hours without reaching anyone. Instead of being rebooked on the same direct routing the following day, I was rerouted onto a much longer itinerary via multiple cities and airlines, which resulted in arriving approximately 30 hours later than scheduled. At Denver airport, there was no visible Air Canada representative available to properly assist. Ground staff offered no real support beyond directing passengers to a phone number. There was no clear communication, no ownership, and no meaningful customer care during a major disruption. The final journey involved three flights instead of the original two, significantly increasing travel time and stress. Overall, the handling of the cancellation and lack of customer support was unacceptable. What could have been better? Clear communication during the cancellation Accessible customer service (phone support that actually answers) Proper in-person assistance at the airport Rebooking onto a comparable routing rather than a significantly longer one

Great setup on both flights except the last flight we got condensed dripping all over me in the last 20 mins of the flight

The last 3 hours it was freezing cold in row 56. Multiple people had their winter coats on and were utilizing the blankets provided by the airline. I also did not have easy access to figure out how to book my food allergy and advance for my meals. Most of everything I received was something I couldn't eat. This needs to be made more accessible. Also, I'm 5'10 which is the average height of the American male. I flew from Philadelphia to Toronto and then to Tokyo and the seats were absolutely unbearable. For that long of a flight it is impossible to get comfortable when doing anything. Flights need to have more space and stop prioritizing costs over people.

Again, we were rerouted all the way to Zurich and had a longer journey than expected.

Was delayed at every point/ connection. Luggages missing for 5days. Had no medications for diabetes and high B/p. when bags where finally delivered on the 30th, the insulin and ozempic were no longer patent, as the ice pack had since dissolved and the authenticity of the med is now questionable, since they must be refrigerated. Please have them refund my bag fees. I should sue them for all the inconveniences caused to me.

The plane was delayed substantially due to a mechanical problem, that being said, the airline was very fair with providing a meal coupon for us. I would rather arrive late on a mechanically sound plane than the alternative. The food served in the plane was just awful, however and I recommend a new catering company.

Everything could have been better. What needed to be wrong with United went wrong

The staff was bit rude when I asked for an extra drink after one beer, asked for one wine glass.

Very good, i got two seats for myself, and was comfortable with the blanket i got

I hated the FRA Airport. Confusing signage, including the path to Immigration and Security It seems that the airport grew haphazardly over the years. I have been through multiple WW Hubs with much better experiences.

Economy Priority seats are extremely uncomfortable. There is no way to escape the boxed in feeling, particularely because the distance between to rows are too short, the hard edge of the front row is keeping legs confined. There is no elevated place to put your feet. I am of average, European size.

Terrible. Both flights were significantly delayed, no luggage, made me check my small bag when many, many others had much larger carry-ons, not even a bottle of water . . . I will not fly Discover Airlines again.

I was deceived on the Kayak site expecting a ticket, but instead finding a "standby" reservation. When I tried to change the ticket, I paid almost twice the price of the original ticket. Then, the airline refused to give me the reserved seat I had chosen and paid for. I think I deserve a refund for this leg of my trip because I was doubly charged and did not receive what I had paid for. I put in a complaint with Lufthansa because the ticket was sold originally sold as a flight they listed. Someone here needs to take responsibility.

Excellent service; they helped me reschedule so I can fly in an earlier flight

I had a good comfortable seat. There was nearly an hour delay. There was an accident with the champagne, but I was well compensated. These things happen sometimes.

Service and food were excellent. Incredibly friendly and competent staff. Flight was delayed over and hour and I had to run between terminals to get my connecting flight.

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

Information on your arrival and departure airports