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Cheap flights from London Heathrow Airport to Seattle from C$ 699

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 23/9. Fares are subject to change and may not be available on all flights or dates of travel.
LHR — SEA
26 Apr — 3 May1
1 adult
1 adult, Economy, 0 bags
Cheapflights Tip: The best prices from London Heathrow to Seattle/Tacoma Intl are usually found in February or January, booked 81 days in advance, depart on a Monday or Tuesday and return on a Wednesday

Cheap flight deals from Heathrow to Seattle

Enter your travel dates to find the best prices.

Cheapest flights from Heathrow to Seattle
Explore the most affordable flight options available from Heathrow to Seattle. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 27 March 2026.

Sat 23/51:05 p.m.
LHR
-
SEA
2 stops40h 05m
United Airlines
Sun 24/511:20 p.m.
SEA
-
LHR
1 stop23h 35m
United Airlines
Deal found 23/3C$ 921
Tue 14/41:05 p.m.
LHR
-
SEA
1 stop15h 35m
Icelandair
Fri 24/47:00 p.m.
SEA
-
LHR
1 stop17h 20m
Icelandair
Deal found 26/3C$ 961
Mon 13/49:25 p.m.
LHR
-
SEA
1 stop31h 15m
Icelandair
Mon 20/43:40 p.m.
SEA
-
LHR
1 stop20h 40m
Icelandair
Deal found 26/3C$ 964
Tue 21/41:05 p.m.
LHR
-
SEA
1 stop15h 35m
Icelandair
Sat 9/57:00 p.m.
SEA
-
LHR
1 stop17h 20m
Icelandair
Deal found 26/3C$ 972
Wed 22/49:25 p.m.
LHR
-
SEA
1 stop28h 30m
Icelandair
Fri 8/57:00 p.m.
SEA
-
LHR
1 stop17h 20m
Icelandair
Deal found 26/3C$ 973
Wed 6/51:05 p.m.
LHR
-
SEA
1 stop15h 35m
Icelandair
Sun 10/57:00 p.m.
SEA
-
LHR
1 stop17h 20m
Icelandair
Deal found 27/3C$ 976
Wed 8/49:25 p.m.
LHR
-
SEA
1 stop28h 30m
Icelandair
Tue 21/47:00 p.m.
SEA
-
LHR
1 stop17h 20m
Icelandair
Deal found 27/3C$ 978
Thu 14/51:05 p.m.
LHR
-
SEA
1 stop12h 50m
Icelandair
Thu 17/93:40 p.m.
SEA
-
LHR
1 stop12h 15m
Icelandair
Deal found 27/3C$ 979
Wed 8/49:25 p.m.
LHR
-
SEA
1 stop28h 30m
Icelandair
Sat 18/47:00 p.m.
SEA
-
LHR
1 stop17h 20m
Icelandair
Deal found 27/3C$ 994

Find flight deals from Heathrow to Seattle

Discover tips and strategies to find the most affordable flight options for your journey from Heathrow (LHR) to Seattle (SEA). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated 27 March 2026.

Round-trip from

C$ 921

One-way from

C$ 699

Popular in

July

Cheapest in

February

Average price

C$ 1,084

Good one-way deal

C$ 840 or less
United Airlines
  • United Airlines
  • 23/5-24/5
  • 3 total stops
  • 63h 40m total
  • London to Seattle
Search Deals
Icelandair
  • Icelandair
  • 23/9
  • 1 total stop
  • 15h 35m total
  • London to Seattle
Search Deals
Highest demand for flights based on searches. 12% potential increase in price (C$ 207 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease (C$ 34 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in March 2026
Search Deals
Price to beat on a one-way flight from London Heathrow to Seattle/Tacoma Intl.
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Heathrow to Seattle that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 629,999 searches. Data last updated 27 March 2026.
Use the filters below to find and compare flights from London Heathrow Airport to Seattle that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

LondonSeattle

LHR - SEA

LHRSEA

London Heathrow

Sun 12/4

6:30 a.m.-4:30 p.m.

1 stop18h 00m

Seattle/Tacoma Intl

Sat 18/4

11:11 p.m.-7:10 a.m.

1 stop23h 59m

C$ 1,127

LondonSeattle

LHR - SEA

LHRSEA

London Heathrow

Thu 21/5

8:40 a.m.-4:30 p.m.

1 stop15h 50m

Seattle/Tacoma Intl

Wed 3/6

6:20 p.m.-12:10 p.m.

Nonstop9h 50m

C$ 1,134

LondonSeattle

LHR - SEA

LHRSEA

London Heathrow

Thu 9/4

9:55 a.m.-4:30 p.m.

1 stop14h 35m

Seattle/Tacoma Intl

Mon 4/5

9:45 p.m.-3:35 p.m.

Nonstop9h 50m

C$ 1,140

LondonSeattle

LHR - SEA

LHRSEA

London Heathrow

Fri 12/6

9:55 a.m.-4:24 p.m.

1 stop14h 29m

Seattle/Tacoma Intl

Mon 22/6

10:05 p.m.-3:35 p.m.

Nonstop9h 30m

C$ 1,145
Quickest round-trip

LondonSeattle

LHR - SEA

LHRSEA

London Heathrow

Mon 8/6

11:40 a.m.-2:00 p.m.

Nonstop10h 20m

Seattle/Tacoma Intl

Mon 22/6

10:05 p.m.-3:35 p.m.

Nonstop9h 30m

C$ 1,161

LondonSeattle

LHR - SEA

LHRSEA

London Heathrow

Thu 7/5

9:55 a.m.-4:30 p.m.

1 stop14h 35m

Seattle/Tacoma Intl

Thu 14/5

8:10 p.m.-2:00 p.m.

Nonstop9h 50m

C$ 1,169

LondonSeattle

LHR - SEA

LHRSEA

London Heathrow

Wed 17/6

6:30 a.m.-4:24 p.m.

1 stop17h 54m

Seattle/Tacoma Intl

Fri 17/7

9:50 p.m.-3:35 p.m.

Nonstop9h 45m

C$ 1,181

LondonSeattle

LHR - SEA

LHRSEA

London Heathrow

Mon 18/5

9:55 a.m.-4:30 p.m.

1 stop14h 35m

Seattle/Tacoma Intl

Tue 2/6

10:05 p.m.-3:35 p.m.

Nonstop9h 30m

C$ 1,190

LondonSeattle

LHR - SEA

LHRSEA

London Heathrow

Wed 1/7

11:20 a.m.-8:19 p.m.

1 stop16h 59m

Seattle/Tacoma Intl

Wed 8/7

7:15 a.m.-6:20 a.m.

1 stop15h 05m

C$ 1,217
Cheapest one-way

LondonSeattle

LHR - SEA

LHRSEA

London Heathrow

Tue 1/9

6:55 a.m.-11:24 p.m.

3 stops24h 29m

C$ 736

Flights are sorted by cheapest round-trip flights first.

Deals found on 25/3

Showing 1-10 of 20 resultsSorted by cheapest first
1
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Best time to book a flight from Heathrow to Seattle

Have a flexible travel schedule? Discover the best time to fly to Seattle from Heathrow with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from London Heathrow Airport to Seattle

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

Use this chart to determine the optimal time to book a round-trip flight from Heathrow to Seattle. Price data was last updated on 13 March 2026.

The price you pay for your flight from London Heathrow Airport to Seattle may vary depending on when you book. For the best chance of a lower fare, look to book 81 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.

What is the cheapest month to book a flight from London Heathrow Airport to Seattle?

Currently, February is the cheapest month in which you can book a flight from London Heathrow Airport to Seattle (average of C$ 685). Flying from London Heathrow Airport to Seattle in July is currently the most expensive (average of C$ 954). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

What is the cheapest time of day to fly from LHR to SEA?

Find hourly flight availability from Heathrow to Seattle. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated 27 March 2026.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from London Heathrow Airport to Seattle as you normally would.

How much does it cost to fly round-trip from London Heathrow Airport to Seattle?

Related info for your journey

Find useful and relevant information for your journey from Heathrow to Seattle. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airport do you fly into for flights to Seattle from London Heathrow?

    Seattle/Tacoma Intl (SEA), located 18.4 km from the city centre, is the airport you fly into when you book flights from London Heathrow to Seattle. 0 airlines have flights to Seattle/Tacoma Intl from London Heathrow on a regular basis. Booking flights from London Heathrow to Seattle/Tacoma Intl should not be difficult; the airport handles an average of 7 inbound flights from London Heathrow per day.

  • How long is the flight from London Heathrow Airport to Seattle?

    A quick flight from London Heathrow Airport to Seattle can take about 15h 50m. United Airlines provides one of the quickest options available for as low as C$ 1,134. There are 7697 km between London Heathrow Airport and Seattle. When browsing for deals, the options you’ll see will be for both direct flights and flights with stops.

  • What are the most reliable airlines from London Heathrow Airport to Seattle?

    Consider KLM (98%), Air France (98%) or Delta (98%) when booking your flight. These represent the most reliable airlines when flying from London Heathrow Airport to Seattle.

  • What are the cheapest flights from London Heathrow Airport to Seattle?

    Looking for the cheapest flight from London Heathrow Airport to Seattle? While on average our users pay C$ 1,064, our data indicates the cheapest price to be C$ 720. The most popular route (London Heathrow - Seattle/Tacoma Intl), is priced around C$ 1,473.

  • Can I find deals for flights from Heathrow to Seattle that include hotel bookings?

    Yes. In addition to deals on Heathrow to Seattle flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Heathrow to Seattle?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Heathrow to Seattle.

  • Can I find deals for business class flights from Heathrow to Seattle?

    Yes. Cheapflights offers flight deals from Heathrow to Seattle by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

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

    Currently, February is the cheapest month in which you can book a flight from London Heathrow Airport to Seattle (average of C$ 685). Flying from London Heathrow Airport to Seattle in July is currently the most expensive (average of C$ 954). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

Travelling to a place near Seattle?

Book flights to Seattle if you plan to visit one of these locations
SeaTac
Leavenworth
Mukilteo
Tacoma
Kent
Bothell
Cashmere
Tukwila
Olympia
Renton
Marysville
Lynnwood
Kirkland

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Can Cheapflights find flights from Heathrow to Seattle with no change fees?

Yes, we can. To see specific flights from Heathrow to Seattle with no change fees, users can toggle flexible booking options after using the search form above to find flights.

Can Cheapflights notify me if prices for flights from Heathrow to Seattle become cheaper?

Yes, Cheapflights has a feature called Price Alert, which notifies users when flight prices change. Track prices for your flight to Seattle from Heathrow today and book when prices fit your budget.

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