SEA - OPO

$258 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 5/12. 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
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Everything you should know

Cheapest round-trip
$478
Overall average: $779
Multiple Airlines
Tue 2/24Tue 3/3
SEA - OPO • 2 stops
Cheapest one-way
$258
Typical prices: $626-$736
British Airways
Tue 5/12
SEA - OPO • 1 stop
Top airlines
KLM
Cheapest • from $479 (round-trip)
Delta
Best reviews • 7.9 score
Airline reviews
Airline reviews
+1
+1
Airline reviews
Airline reviews
+1
When to book
3 weeks
in advance
Our data shows that travelers who book at least 3 weeks in advance save around 33% compared to booking last minute.
Insights
Insights
Insights
Insights
When to travel
January
Cheapest • 49% price drop
April
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
+1
Start a new search
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, Feb 24 - Tue, Mar 3
Multiple Airlines Logo
8:00 am - 6:30 pm
SEA
-
OPO
26h 30m
2 stops
Multiple Airlines Logo
1:45 pm - 1:20 pm
OPO
-
SEA
31h 35m
1 stop
$478Multiple Airlines
Tue, Feb 24 - Tue, Mar 3
KLM Logo
1:40 pm - 10:30 am
SEA
-
OPO
12h 50m
1 stop
KLM Logo
11:15 am - 11:35 am
OPO
-
SEA
32h 20m
1 stop
$479KLM
Tue, Feb 24 - Tue, Mar 3
Iberia Logo
6:44 am - 7:40 am
SEA
-
OPO
16h 56m
2 stops
Iberia Logo
8:20 am - 11:04 pm
OPO
-
SEA
22h 44m
2 stops
$481Iberia
Mon, Apr 13 - Thu, Apr 23
Delta Logo
1:45 pm - 10:30 pm
SEA
-
OPO
24h 45m
2 stops
Delta Logo
5:00 am - 4:30 pm
OPO
-
SEA
19h 30m
1 stop
$482Delta
Mon, Apr 13 - Thu, Apr 23
Delta Logo
5:30 pm - 3:30 pm
SEA
-
OPO
14h 00m
1 stop
Delta Logo
5:00 am - 4:30 pm
OPO
-
SEA
19h 30m
1 stop
$483Delta
Tue, Feb 24 - Tue, Mar 3
Delta Logo
8:00 am - 10:30 am
SEA
-
OPO
18h 30m
2 stops
Delta Logo
5:00 am - 11:35 am
OPO
-
SEA
14h 35m
1 stop
$484Delta
Tue, Feb 24 - Tue, Mar 3
KLM Logo
3:05 pm - 10:25 pm
SEA
-
OPO
23h 20m
1 stop
KLM Logo
11:15 am - 11:35 am
OPO
-
SEA
32h 20m
1 stop
$485KLM
Tue, Feb 24 - Tue, Mar 3
Delta Logo
3:05 pm - 3:25 pm
SEA
-
OPO
16h 20m
1 stop
Delta Logo
5:00 am - 11:35 am
OPO
-
SEA
14h 35m
1 stop
$486Delta
Tue, Feb 24 - Tue, Mar 3
United Airlines Logo
9:00 am - 9:30 am
SEA
-
OPO
16h 30m
2 stops
United Airlines Logo
12:30 pm - 12:59 am
OPO
-
SEA
20h 29m
2 stops
$487United Airlines
Tue, Feb 24 - Tue, Mar 3
United Airlines Logo
9:00 am - 9:30 am
SEA
-
OPO
16h 30m
2 stops
United Airlines Logo
12:30 pm - 12:59 am
OPO
-
SEA
20h 29m
2 stops
$488United 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 $485 (return) on average. On the other hand, the most expensive months are December and June, where the average cost of round-trip tickets is $1,451 and $1,320 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 33% 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$258
Best time to beat the crowds with an average 49% drop in price.
Most popular time to fly and prices are also 7% lower on average.
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 $258 for a one-way ticket and $478 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 $981 and an overall rating of 7.7.

  • 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 8125 reviews
8.1Boarding
7.2Food
8.5Crew
7.8Entertainment
7.9Comfort
Airline reviews

It was last minute due to weather - considering - it was amazing! Good smiles, friendly staff and they were making sure we knew what was going on when and where.

10.0 ExcellentZebrina, Jan 2026
LGA - CAE
Read more Delta reviews

It was last minute due to weather - considering - it was amazing! Good smiles, friendly staff and they were making sure we knew what was going on when and where.

delta last minute gave me a boarding pass for a different flight with no confirmation that they were changing it

The flight was comfortable and uneventful, which is what I desire

The service from the flight attendants were of supreme quality. They greeted and treated everyone with a wide smile. This is totally absent nowadays. Kudos to them!!!!

Excellent flight and got us around tough weather. Only issue was seat TV did not work and crew tried to reboot.

Very large passenger too space from my own seat. Arm board couldn’t be lowered because of his size. It wads very uncomfortable trip, as the flight was full couldn’t move anywhere having back pain because of the position in which I was the entire flight.

was sitting in the jet bridge for 10 minutes in -20 degree weather waiting for my bag

Outdated equipment in disrepair, wifi inoperable. Broken seats, taped air vents, generally poor condition, the 717 showed its age and lack of upkeep.

My flight out of Baton Rouge to Atlanta was delayed by a half hour. This got us into Atlanta airport 30 minutes late. I ran through the airport to get to my connecting flight. As I approached the boarding gate, I saw the boarding door was still open and a passenger was being checked in. But when I got to the gate, the boarding agent told me they had already given away my seat and there were no empty seats on that flight. So I had to take a later flight. That has never happened to me before. Very frustrating.

Connection through Atlanta was difficult. Mechanical issue on plane caused a two hour delay. New gate was a mile away.

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.

Ad experience - been flying many years with them but they are losing out to other carriers with their service and bagage / seating policy. My 2 12-yo kids were not placed with the parent. Absurdity.

Short flight so it was okay. Nice crew, all very pleasant and professional. We were near the back in row 27 so just as we got our drinks, we started our descent so had to drink very quickly!

The baggage drop-off in Stuttgart is bad: after online check-in you cannot use the automated baggage drop off as indicated on the website. You can use the terminals but have to cue to 1 of three open and slowly working counters to drop the bags. took about 45 minutes wait time.

In overall it was a good experience, the only down point was that the entertainment screen was working properly.

HORRIBLE, my initial flight was cancelled, they made me pay $200 extra dollars and that got cancelled as well! After 6 cancellations I decided to get a refund because I needed to get home to my babies. Out of $1000+ dollars they offered me only $40 in refund! Totally unacceptable! The flight that they cancelled I was able to fly it on another airline. I had to spend $400 on one way tickets just to get home! I’m still getting the runaround.

First class ticket gets you a choice of chips or nuts. . Just like economy Southwest. Also no screen in the seats. This is first class???!

Seated dude next to me even though lots of empty rows. But main thing was we sat on the tarmac after landing for 30 minutes because of, in the words of the dude who sat next to me, “operational incompetence”. We got changing directions about where to pick up gate checked bags. Pilot and flight attendant were awesome though.

The food was terrible this time. Otherwise pleasant, quiet, on-time.

It was a pretty standard flight... until the almost hour and a half spent on the taxi way. I get that the weather has been poor but the delay had nothing to do with the weather and more to do with a plane with several issues tying up the gate. I get that that happens from time to time but this has been EVERY flight I've been on for the past 5 years and I fly 3 to 5 times a year. This isn't just United... it's American, it's Delta. It's an issue with the entire industry. I work for UPS and packages on a cargo plane get better service than people do these days. Anymore I HATE flying.

Flight arrived 30 min early and bag was waiting at the baggage pickup. United Club HNL was one of the nicest in the system

Unfortunately weather delayed our flight waiting for our plane to arrive and due to a little snow time was needed to deice the plane so departure was very delayed and I missed the connecting flight

Very good. Because of the delays with my previous flight, I missed my connection, but I was able to book another flight through the United app easily.

I wish there were outlets to charge my iPhone. The crew was great; we had a female pilot who was great with explaining what was happening and delays,

My, Syed Zawar Hussein Shirazi frequently flyer membership number was not included on my boarding pass from O’Hare to Istanbul despite my reminder to the attendant at check in. Further she forgot to give me my boarding pass form Istanbul to Lahore and she needs to improve her customer service, please 🙏

Everything about that day was great I was happy with how things went as a first time traveling with the airline thank you for all that you’ve doing by taking us there to our various destinations thanks.

They oversold the tickets by one which was my ticket so I didn’t have a ticket till last second

Not good. I was supposed to be in Mint but got in economy class

Service was slow and checked bag was off last evening when flying business

Turkish Airline canceled our tickets in the very last minute, with our luggage and everything else, all prepared and good to go. It’s clear that they sold the tickets for better money to someone else. Bad, Bad, Bad business!!!

Awful seating. Bad food. Staff only have one bottle of water and no cans.

it was like a banya -so hot... They did provide a great experience with special food. one toilet broke midflight In general it was a peaceful and relaxing flight - for business class it was good.

Chicago to Istanbul was a much better experience than I expected since I’m more accustomed to Qatar Airways business class. The business lounge in the Istanbul airport was amazing - loved the lockers and phone charging stations, and the bathroom was a spa experience in itself. The onward leg from Istanbul to Karachi was utterly disappointing. Terrible plane, and I felt like I was in economy - the seats don’t come near to lying flat and the food was mediocre. What a sad downgrade - it isn’t as though the ticket on that leg was cheaper. So, on that front, there’s no contest with Qatar airways.

Second leg of Turkish Airline with Indigo is disaster for following reason. 1) You have to carry your cabin bags through ladder to boeing 777 because it was parked somewhere in parking lot and was not given a gate to board passengers and this seems to be people traveling to and fro from those flights and is not issue with flight itself. 2) I choose non vegetarian food on Turkish portal way ahead of checkin to entire trip, However the Indigo flight gave me random veg food saying they code veg food code from Turkish. 3) Indigo did not served any alcoholic beverages stating some weird reason which is non nonsensical. 4)Indigo have TV screens in front of you but it displays nothing except "Welcome Onboard" with annoying white black ground in dark flight. This is the most stupidest and annoying part because you are held hostage for 7 hours and only thing you could do is stare back at white screen which does not have entertainment package or even flight tracker. Such a shame.

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.

Missed it by a couple minutes and couldn’t find an alternative flight so had to spend the night in DC and after much shuffling from 1 airline to another managed to get a United to Frankfurt.

There were only 2 toilets and one of them did not work in business class. We are not allowed to cross classes so had to wait in line to use the toilets!! The entertainment touch display was finicky and did not work all the time.

We missed our flight. There was not enough time built into the layover to get through immigration, customs, bagclaim, bag rechecking, and the long trip to another terminal and gate. Kayak really screwed up. We took the bus up to Wisconsin and then were picked up in Brookfield by private car. It was lucky we didnt miss the last bus out.

I tried both on line and by calling the Customer Service line to arrange for a special meal as i have food intolerances. I was under the impression from your service representative that I was successful. I was not. I cannot eat spicy foods and get very ill if i eat bell peppers. I could not eat either menu choice and no special meal was actually ordered. ( your representative tried to order it for a flight that did not have meal service!!! - found this out later). Your wonderful cabin crew managed to put together a fruit, salad, roll and cheese tray for me so I had something to eat. WHY WOULD YOU SERVE SPICY FOOD, WITH NO MILDER OPTION,ON AN INTERNATIONAL FLIGHT???

Crew was professional and great, flight was clean. However food was pathetic. I ordered a Hindu meal assuming no meat but they served chicken. Need to be very specific- Hindu meal should be categorize as Vegetarian - no meat or egg. Or it should be specific that we are serving meat.

Late flight Delays Poor service Poor staff Worst airline ever

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.

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

Information on your arrival and departure airports