SEA - LHR

C$ 338 Find Cheap Flights from Seattle to London Heathrow Airport

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 London departing on 20/9. 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

KAYAK searches hundreds of travel sites at once for deals on flights to London Heathrow Airport

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Seattle to London, 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 London, as well as popular online travel agencies
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Flight Deals

Cheap Flights from Seattle to Heathrow (SEA-LHR)

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

Tue, 9 Sep - Wed, 17 Sep
United Airlines Logo
7:15 a.m. - 6:30 a.m.SEA-LHR
15h 15m1 stop
United Airlines Logo
6:55 a.m. - 4:59 p.m.LHR-SEA
18h 04m1 stop
C$ 691United Airlines
Find Deal
Wed, 21 Jan - Wed, 28 Jan
Lufthansa Logo
3:40 p.m. - 11:50 a.m.SEA-LHR
12h 10m1 stop
Lufthansa Logo
6:35 a.m. - 1:20 p.m.LHR-SEA
14h 45m1 stop
C$ 692Lufthansa
Find Deal
Tue, 10 Feb - Thu, 19 Feb
United Airlines Logo
3:40 p.m. - 11:50 a.m.SEA-LHR
12h 10m1 stop
United Airlines Logo
4:40 p.m. - 1:20 p.m.LHR-SEA
28h 40m1 stop
C$ 693United Airlines
Find Deal
Tue, 26 Aug - Fri, 5 Sep
 Logo
2:29 p.m. - 2:10 p.m.SEA-LHR
15h 41m1 stop
 Logo
7:25 a.m. - 4:59 p.m.LHR-SEA
17h 34m1 stop
C$ 698
Find Deal
Tue, 26 Aug - Fri, 5 Sep
Delta Logo
5:35 p.m. - 11:20 a.m.SEA-LHR
9h 45mdirect
Delta Logo
9:00 a.m. - 5:40 p.m.LHR-SEA
16h 40m1 stop
C$ 700Delta
Find Deal
Sun, 21 Sep - Mon, 6 Oct
Delta Logo
8:25 p.m. - 2:15 p.m.SEA-LHR
9h 50mdirect
Delta Logo
9:55 a.m. - 11:50 a.m.LHR-SEA
33h 55m1 stop
C$ 702Delta
Find Deal
Sat, 8 Nov - Fri, 21 Nov
Icelandair Logo
2:35 p.m. - 10:50 a.m.SEA-LHR
12h 15m1 stop
Icelandair Logo
12:15 p.m. - 5:00 p.m.LHR-SEA
12h 45m1 stop
C$ 720Icelandair
Find Deal
Tue, 10 Feb - Sat, 21 Feb
Icelandair Logo
2:35 p.m. - 7:30 p.m.SEA-LHR
20h 55m1 stop
Icelandair Logo
12:15 p.m. - 5:00 p.m.LHR-SEA
12h 45m1 stop
C$ 721Icelandair
Find Deal
Tue, 23 Sep - Sat, 11 Oct
British Airways Logo
8:20 p.m. - 1:40 p.m.SEA-LHR
9h 20mdirect
British Airways Logo
9:50 a.m. - 11:35 a.m.LHR-SEA
9h 45mdirect
C$ 758British Airways
Find Deal
Sat, 3 Jan - Sat, 10 Jan
 Logo
11:59 p.m. - 7:30 a.m.SEA-LHR
23h 31m1 stop
 Logo
4:40 p.m. - 1:20 p.m.LHR-SEA
28h 40m1 stop
C$ 768
Find Deal
Expert advice

Expert advice for your flight from Seattle to London

 
Snippets provided in this section are AI-generated based on a summarisation of KAYAK-commissioned articles. The articles are presented as-is, for general informational purposes only, and may not be up-to-date. The opinions contained in the articles are original to the author and reflect their authentic experience, which may vary significantly from the experience of others.
KAYAK teamed up with top travel experts to share the best tips for your journey.
Airlines
Delta

Delta One offers lie-flat seats with privacy doors on select aircraft for enhanced comfort.


Delta's Wi-Fi is free for SkyMiles members on most planes, enhancing connectivity.

Read more about Deltaby Stefanie Waldek
Virgin Atlantic

Virgin's Upper Class offers fully flat beds and exclusive lounge access for luxury travel.


Virgin's Economy Delight includes extra legroom and priority boarding for added comfort.

British Airways

BA's premium economy offers 18 cm extra legroom, ideal for long-haul comfort.


BA's Club World provides priority boarding and enhanced meal service for a premium experience.

Airports
SEA

Use the SEA Spot Saver for free expedited security screening. Book online or via the flySEA app for faster access.

Read more about SEAby Harriet Baskas
LHR

Take the Elizabeth Line from Heathrow to central London for a cost-effective journey. It's half the price of the Express.

Read more about LHRby Duncan Madden
Our travel experts
Stefanie Waldek

Stefanie Waldek

Expert on Delta

Stefanie Waldek

Stefanie Waldek

Stefanie Waldek is a freelance space, travel, and design writer based in Saratoga Springs, NY. Her words have appeared in Space.com, Travel + Leisure, Condé Nast Traveler, Architectural Digest, and House Beautiful, among other publications. An expert in aviation and expedition cruising, Stefanie is frequently up in the air or on the sea, likely en route to Antarctica or the Arctic.

Read more
Laura Ratliff

Laura Ratliff

Expert on Virgin Atlantic

Laura Ratliff

Laura Ratliff

Laura Ratliff is a New York-based writer and editor. She lives in downtown Brooklyn with her husband and their beloved dogs. Originally from Texas, she now considers New York City her home. She typically spends more than 200,000 miles on a plane each year and stays in plenty of hotels.

Read more
Duncan Madden

Duncan Madden

Expert on British Airways and LHR

Duncan Madden

Duncan Madden

Duncan is a freelance travel writer, copywriter and book author in constant search of travel stories and the perpetual sensation of being on holiday. He’s never happier than when on a dusty trail in search of empty waves or ducking under the piste tape in search of snowbound solitude. British born, living in Germany, but happiest heading for the horizon. His first book, Found in Translation, explores the etymologies and stories of country names around the world and is out now.

Read more
Harriet Baskas

Harriet Baskas

Expert on SEA

Harriet Baskas

Harriet Baskas

Harriet is an award-winning journalist who is happiest in an airport or an unusual museum. Her stories about airports, air travel, and the business of travel have appeared on NBC News, CNBC, USA TODAY, The Points Guy and other outlets. She is the creator of the StuckatTheAirport.com blog and the author of nine books. When not out on the road or exploring the latest airport amenities, she’s home in Seattle getting ready for the next adventure.

Read more
Booking Insights

KAYAK's insights & trends for Seattle to London flights

Get data-powered insights and trends into flights from Seattle to London 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 London Heathrow Airport?

What’s the cheapest day of the week to fly from Seattle to London Heathrow Airport?

The average price of all round-trip flights from Seattle to London Heathrow Airport clicked on KAYAK for each day over the last 12 months.

If your flying dates are flexible, you should consider flying to London Heathrow Airport on a Sunday, as we generally find the cheapest rates on that day for this route. On the other hand, Friday is the most expensive day to fly from Seattle to London Heathrow Airport. For your return ticket, we recommend flying on a Tuesday and avoiding Sundays for the best deals.

What is the cheapest month to fly from Seattle to London Heathrow Airport?

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Seattle to London Heathrow Airport, 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 London Heathrow Airport is March, where tickets cost C$ 943 (return) on average. On the other hand, the most expensive months are June and December, where the average cost of round-trip tickets is C$ 1,497 and C$ 1,392 respectively.

Can I save money by flying with a layover from Seattle to London Heathrow Airport?

The average round-trip price for all non-stop flights, flights with one layover, and flights with two layovers for the route found by users searching on KAYAK in the last 2 weeks.

Yes, flying with a layover may cost you more time, but you can also save money on the route, with a 1 stop layover the cheapest option at C$ 867 on average.

How far in advance should I book a flight from Seattle to London Heathrow Airport?

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 London Heathrow Airport, 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 London Heathrow Airport, you should book around 4 weeks before departure, which saves you about 23% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 8 weeks before departure.

Good to know

Low seasonJanuary
Cheapest flightC$ 338
Best time to beat the crowds (7% less expensive on average)
Most popular time to fly and prices are also 6% lower on average.
Flight from Seattle to London Heathrow Airport

When to book flights from Seattle to London

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

Flights from Seattle to London: the best tips from KAYAK users' own experiences

Insights shared by verified travellers who flew the route from Seattle to London 
Verified travelerFlew with British AirwaysSEA-LHRApr 2025
Make sure you have plenty of time between flights if you are delayed.
Verified travelerFlew with British AirwaysSEA-LHRApr 2024
Bring a sack lunch -- airport food was very expensive.

FAQs for booking Seattle to London Heathrow Airport flights

  • What is the cheapest flight from Seattle to London Heathrow Airport?

    In the last 3 days, the lowest price for a flight from Seattle to London Heathrow Airport was C$ 245 for a one-way ticket and C$ 501 for a round-trip.

  • Which airlines offer Wi-Fi service onboard planes from Seattle to London Heathrow Airport?

    Air France, Delta, Virgin Atlantic, American Airlines, and KLM offer inflight Wi-Fi service on the Seattle to London Heathrow Airport flight route.

  • Which aircraft models fly most regularly from Seattle to London Heathrow Airport?

    The Boeing 787-10 Dreamliner is the aircraft model that flies most regularly on the Seattle to London Heathrow Airport flight route.

  • Which airline alliances offer flights from Seattle to London Heathrow Airport?

    oneworld, and SkyTeam are the airline alliances operating flights between Seattle and London Heathrow Airport, with SkyTeam being the most commonly used for this route.

  • On which days can I fly direct from Seattle to London Heathrow Airport?

    There are direct flights from Seattle to London Heathrow Airport on a daily basis.

  • Which is the best airline for flights from Seattle to London, Icelandair or British Airways?

    The two airlines most popular with KAYAK users for flights from Seattle to London are Icelandair and British Airways. With an average price for the route of C$ 761 and an overall rating of 7.0, Icelandair is the most popular choice. British Airways is also a great choice for the route, with an average price of C$ 1,128 and an overall rating of 6.6.

  • How does KAYAK find such low prices on flights from Seattle to London Heathrow Airport?

    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 London Heathrow Airport.

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

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to London Heathrow Airport from Seattle is likely to change within 7 days, so travellers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Seattle to London Heathrow Airport?

    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 London Heathrow Airport with an airline and back to Seattle with another airline.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Seattle to London Heathrow Airport?

    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 London Heathrow Airport 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 London Heathrow Airport

  • Looking for a cheap flight? 25% of our users found flights on this route for C$ 563 or less one-way and C$ 988 or less round-trip.

Prefer to fly direct from Seattle to London Heathrow Airport?

 
Direct data is based off flight results for the next 60 days. Find direct flights from all airlines flying direct from Seattle/Tacoma Intl to London Heathrow.
Find which airlines fly direct from Seattle/Tacoma Intl Airport to London Heathrow Airport, which days they fly and book direct flights.

Direct departures

Seattle/Tacoma Intl to London Heathrow

Monday

Aer Lingus,Air France,Alaska Airlines, +8 more

Aer Lingus,Air France, +9 more

Tuesday

Aer Lingus,Air France,Alaska Airlines, +8 more

Aer Lingus,Air France, +9 more

Wednesday

Aer Lingus,Air France,Alaska Airlines, +8 more

Aer Lingus,Air France, +9 more

Thursday

Aer Lingus,Air France,Alaska Airlines, +8 more

Aer Lingus,Air France, +9 more

Friday

Aer Lingus,Air France,Alaska Airlines, +8 more

Aer Lingus,Air France, +9 more

Saturday

Aer Lingus,Air France,Alaska Airlines, +8 more

Aer Lingus,Air France, +9 more

Sunday

Aer Lingus,Air France,Alaska Airlines, +8 more

Aer Lingus,Air France, +9 more

See more nonstop flights

Direct returns

London Heathrow to Seattle/Tacoma Intl

Monday

Aer Lingus,Air France,Alaska Airlines, +8 more

Aer Lingus,Air France, +9 more

Tuesday

Aer Lingus,Air France,Alaska Airlines, +8 more

Aer Lingus,Air France, +9 more

Wednesday

Aer Lingus,Air France,Alaska Airlines, +8 more

Aer Lingus,Air France, +9 more

Thursday

Aer Lingus,Air France,Alaska Airlines, +8 more

Aer Lingus,Air France, +9 more

Friday

Aer Lingus,Air France,Alaska Airlines, +8 more

Aer Lingus,Air France, +9 more

Saturday

Aer Lingus,Air France,Alaska Airlines, +8 more

Aer Lingus,Air France, +9 more

Sunday

Aer Lingus,Air France,Alaska Airlines, +8 more

Aer Lingus,Air France, +9 more

See more nonstop flights

Reviews of the top 4 airlines flying from Seattle to London

 
See real verified KAYAK customer reviews for airlines flying from Seattle to London. 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 London? 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.
7.4
Virgin AtlanticOverall score based on 657 reviews
7.7Boarding
6.9Food
7.5Entertainment
7.3Comfort
8.1Crew
Airline reviews

The staff was not very polite but the flight was very very nice and comfortable and the entertainment was great

10.0 ExcellentSiten, Aug 2025LHR - JFK
Read more Virgin Atlantic reviews

The staff was not very polite but the flight was very very nice and comfortable and the entertainment was great

Great crew - old style upper class seats on the older fleet now feels dated

Premium economy more comfortable than economy, but not by much. Did was awful, do not try the omelette. Flight crew were helpful. Flight was delayed by over an hour. Overall but bad, arrived safely and thank God.

Food was excellent. Service was very good. Staff was very helpful to all passengers.

The crew was excellent as ever on Virgin. The special meal was poor unfortunately. More significantly when we arrived at Manchester Airport there was no air bridge provided and we had to exit the plane down a rickety stair case. This is unacceptable for a transatlantic flight. Whilst I understand that this is the airport’s fault at the end of the day the airline is responsible for our transportation and needs to do something.

Super friendly and helpful staff, from check-in desk to cabin crew.

Following a paid seat upgrade for enhanced comfort, I encountered an unacceptable odor in my assigned area. It took three hours for the crew to relocate me, and the replacement seat was unacceptably close to the lavatory, offering no improvement.

Good overall. Cannot fault the airlines. I have had better entertainment systems before ie ice in Emirates but it was not too bad. Food was decent and staff were friendly.

I did not fly by vergin atlantic from bangalore to vasco da gama

Your flight delayed at Heathrow n I almost missed my mother funeral.you idiots. I had to waste 10 hours in different airports. Thank your stars I'm not suing you.

The flight was delayed and as a consequence we missed our connecting flight. Were stuck for another 6h in Reykyavik. Appreciated that we got a generous food voucher at least. Would have liked to see more information upon arrival including a person waiting for connecting flight travellers and informing already that we will not catch the flight and directing us to the office dealing with the matter; unfortunately that didnt happen and we hence first needed to find out whether flight had indeed left already and then locate the adequate office to help us with booking us on the next connecting flight. Also my suitcase broke and it is not clear whether it is happened on the leg with Iceland Air from DC to Reykyavik or on the leg with Lufthansa from Reykyavik to Frankfurt. Finally, understood that it is a low cost company but at least provision of earplugs for free would have been nice, instead of making them buy.

Great experience on Icelandair flight from Newark to Amsterdam by way of Reykjavík. Courteous and professional staff. Food was solid. Service - outstanding. Cabin was a little warm.

Good service. No complementary food for international flight. WiFi kinda pricey. Got the job done for the right price.

Still one of my favorite airlines, but the entertainment options were a bit lacking. It didn't help that my screen didn't work on one of the legs of the trip.

The plane was very small and the aisle was so narrow that every time someone walked by they rubbed against me, so it was very uncomfortable.

Everything was good. Only issue comes from being vegan and flying. The food options are super limited.

Overall good for an economy fare. IMO the movie selection could be improved. Great that you can now connect bluetooth headphones to the entertainment system.

Paid for a Premium seat...minimal recline, no footrest. Maybe slightly wider than a cheap economy seat. Zero chance of getting any rest on this plane

Comfort of seats is not good. Like sitting on a rock for 6 hours. Also no in flight food and limited beverages unless you pay is not nice. Need flight to be dark during the “night” but attendants don’t ask for shades to be lowered..

Seats in premier saga class were narrow and hard. Very uncomfortable for a 5-hour flight.

It was extremely cold in the back of the plane. The seats are uncomfortable and space very small. Crew was excellent as usual.

Check in needed to be in person, not nice. Also I won’t do connections in Charlotte again because you need to go through security again and short connections become a problem

Iberia lost my bag, said they found it in another country, said they sent it to me, but never did. Went my whole trip without my stuff, but expecting it to show up because that’s what they said would happen. Their communication sucks, their website sucks, and to top it all off, their seats are small and uncomfortable. They’re bad at their jobs and they should feel bad about themselves. Do not even get me started on the flight home. AVOID!

I described my experience in the previous window. I didn't realize that there would be another opportunity for this flight. Please look at my response in the previous window.

Boarding was 2 1/2 late no explanation Captain said he did not know why, but he rested at home for an extra couple of hours. Food was edible, Nothing more.

I liked the comfort of the plane. It was unexpected from past experiences.

BEWARE!!! Iberia changes your seats at random. I paid for a window seat and they changed it to one in the middle aisle resting against the bathroom- can’t lean back + hear every flush. This on a 11 hour flight.. There were families that were broken up with separate seats all over the plane. Lots of upset passengers showing their seat confirmation to the besieged and helpless airline steward. Also, the gluten free meal was tasteless.

Chair is very high. Your feet cannot touch the ground for 8 hours flight. It was a nightmare. Food was bad.

ground crew and check-in was pathetic - insisted on charging me for luggage even though the ticket said it was already included. They also accidentally sent my luggage through without a luggage tag and had to retrieve it. Generally, it was like a bad movie.

Moved the flight an hour later, were not reliable about confirmation, website didn't work, no gate information, boarding was a mad house. Flight itself was fine and short. Organization needs work.

Although the crew were great and the good nice, I might as well have been on Ryanair for the amount of space I had. Not good enough BA. I’d rather pay more and not feel like a human sardine.

Love the A380 - loads of room. Headphone socket on my seat didn’t work. Sounds like a trivial issue? Well when flying long-haul the in-flight entertainment is what keeps you going so when it doesn’t work it’s a disaster. Pay attention to the details please BA. Spoiled what was otherwise an excellent flight with the usual brilliant crew.

Crew were fantastic can’t fault them at all. Couldn’t do enough for us

Crying baby the ENTIRE flight. Not your fault, but I paid 2700 for a premium economy ticket and it wasn't worth it. should have just stuck with coach. flight attendants very mediocre - minimal effort. Plane didn't seem very clean. Didn't have any cleansing wipes - most airlines give you this when you board. Flat screen scrolling didn't work. Toiletry case a joke - why bother at all?

I enjoyed the comfort of Premium Economy. The Purser on London-Nairobi was a little testy, snappish in his tone. I understand stressed, tired, etc but his tone in addressing passengers I found wanting.

Very good crew. The seating in economy plus was excellent, and I slept most of the way. The diabetic meal that I requested was almost tasteless--about a 2 on a ten-point scale.--so I ate little. And why bother serving dinner to fliers at midnight?! I had eaten a meal at the airport six hours earlier. A good breakfast would be better.

Flight was delayed. Though I checked in with BA live chat three times, our special meals were not provided.

My experience with British Airways is excellent, thanks for all 🫶🏻✈️

The crew is very friendly and helpful. The food is good for airplane food. The flight is long and hard to sleep. The leg space is great. The plane arrived in plenty of time.

Enjoyable flight, helpful crew everything was organized to accommodate passengers.

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

Information on your arrival and departure airports

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