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

Airfare is below average for this route at the moment. Seattle to London Heathrow Airport flights typically cost between C$ 911 and C$ 1,237 in September. The cheapest round-trip price found within the last 3 days was C$ 708 on British Airways (3 Sep-26 Sep).

Question 1

What’s the cheapest layover airport for flights from Seattle to London Heathrow Airport?

Accepted Answer

Reykjavik (KEF) is the most affordable 1-stop option, with an average round-trip price of C$ 707.

Question 2

Which airport typically offers the quickest layover for flights from Seattle to London Heathrow Airport?

Accepted Answer

Flights via Dublin (DUB) offer the fastest connection on this route, with an average layover time of 2h 21m.

Question 3

What’s the fastest layover option from Seattle to London Heathrow Airport?

Accepted Answer

Flights via Dublin (DUB) have the shortest average one-way travel time for 1-stop routes: 2h 56m.

Question 4

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

Accepted Answer

Airfare is below average for this route at the moment.Seattle to London Heathrow Airport flights typically cost between C$ 911 and C$ 1,237 in September.
The cheapest round-trip price found within the last 3 days was C$ 708 on British Airways (3 Sep-26 Sep).

Question 5

What’s the top layover airport for flights from Seattle to London Heathrow Airport?

Accepted Answer

Reykjavik (KEF) – chosen by Cheapflights users on 55% of one-stop itineraries from Seattle to London Heathrow Airport on Cheapflights.

Question 6

What are the cheapest airlines flying from Seattle to London Heathrow Airport round-trip?

Accepted Answer

Flying on British Airways is currently your cheapest option to London Heathrow Airport, with prices starting at C$ 708. Additional round-trip tickets that might be worth considering are offered by Delta and SWISS, with the lowest prices starting at C$ 709 and C$ 711, respectively. Users have found that British Airways is 35% cheaper than the other options available to this destination.

Question 7

What are the cheapest airlines to fly from Seattle to London Heathrow Airport one-way?

Accepted Answer

One-way options have recently been found by users for as low as C$ 357 on Icelandair. Other airlines that offer cheap prices include Lufthansa from C$ 362 and WestJet from C$ 423 one-way.

Question 8

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

Accepted Answer

The best time to book flights from Seattle to London Heathrow Airport is 32 days before your desired departure date. The cost of your flight will likely increase significantly if you book two weeks in advance of your flight.

Question 9

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

Accepted Answer

Currently, January is the cheapest month in which you can book a flight from Seattle to London Heathrow Airport (average of C$ 560). Flying from Seattle to London Heathrow Airport in July is currently the most expensive (average of C$ 857). 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.

Question 10

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

Accepted Answer

Travelers seeking maximum savings on their Seattle to London Heathrow Airport flight should consider departing on Sunday at noon when fares are most often at their lowest. Friday at noon flights should be avoided if possible as fares are typically the most expensive at this time.

Question 11

Weekly flight availability from Seattle to London Heathrow Airport

Accepted Answer

The most flights from SEA to LHR are scheduled on a Monday (22 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (16 on average).

Question 12

E

Accepted Answer

In terms of precipitation, rainfall in London Heathrow Airport ranges from 40.0 - 70.0 mm per month. January is typically the wettest month, when rainfall can reach 70.0 mm. July is typically the driest time to visit London Heathrow Airport when rainfall is around 40.0 mm.

Question 13

E

Accepted Answer

If weather is an important factor for your trip to London Heathrow Airport, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 17.0 C. Travellers hoping to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 4.0 C).

Question 14

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

Accepted Answer

While on average a flight from Seattle to London Heathrow Airport is generally C$ 1,441, our data shows the cheapest flight currently is C$ 586. When looking at the most popular route, (Seattle/Tacoma Intl - London Heathrow), you can expect to pay C$ 657 for that flight.

Question 15

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

Accepted Answer

Looking for the most reliable airlines to get you to your destination on time? Our data shows these are most likely to get you from Seattle to London Heathrow Airport on time: Scandinavian Airlines (92%), KLM (91%), Air France (91%).

Question 16

What are the most popular airlines that fly from Seattle to London Heathrow Airport?

Accepted Answer

When booking a flight from Seattle to London Heathrow Airport, you may want to consider flying on British Airways, Icelandair or Iberia as they are the most popular for this route.

Question 17

What is the cheapest day to fly round-trip from Seattle to London Heathrow Airport?

Accepted Answer

Users have found that flying from Seattle to London Heathrow Airport on a Thursday typically leans towards higher prices. However, this doesn’t mean you still can’t find a deal. Flexibility with other aspects of your flight can still land a great price for your trip.

Question 18

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

Accepted Answer

When searching for a good deal, it’s best to be prepared for potential fluctuations in price. We recommend booking at least 51 days in advance, which can save you up to 44% on flights from Seattle to London Heathrow Airport compared to booking the week you need them. Waiting 51 days out may not be for everyone, so we have options available for flights within the next two weeks, with the lowest price starting at C$ 1,104. For sooner than that we have options available in the next 3 days from C$ 1,346.

Question 19

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

Accepted Answer

October is one of the best times of the year to fly to London Heathrow Airport from Seattle. Prices for October average C$ 1,054 per person but you can even find prices for as low as C$ 739. The most expensive prices can be found in the month of June. Opting for a October flight can save you 30% on your journey compared to booking in June

Question 20

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

Accepted Answer

Unlike in the afternoon, when flights are generally more expensive, you can save up to 28% on flights from Seattle to London Heathrow Airport by exploring options for tickets in the morning.

Question 21

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

Accepted Answer

Seattle/Tacoma Intl (SEA) is the airport you will fly out of if you book a flight from Seattle to London Heathrow. You should not have trouble finding flights to London Heathrow from Seattle/Tacoma Intl; the airport handles an average of 21 outbound flights to London Heathrow per day. You should also have plenty of airline options to choose from since 4 airlines have flights from the Seattle airport to London Heathrow. It is only a 18.4 km journey to Seattle/Tacoma Intl (SEA) from Seattle’s city centre.

Question 22

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

Accepted Answer

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

Question 23

How can I find direct flights from Seattle to Heathrow?

Accepted Answer

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

Question 24

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

Accepted Answer

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

Question 25

How does Cheapflights help users find flights from Seattle to Heathrow?

Accepted Answer

900+ travel sites are searched through when a user searches for a flight using Cheapflights. From the search interface, users can use filters to choose airlines, airports, flight times, cabin classes and more to their preference. Book your flight to Heathrow from Seattle today with Cheapflights!

Question 26

Why should you use Cheapflights to find cheap flight tickets from Seattle to Heathrow?

Accepted Answer

Millions of users choose and trust Cheapflights to book the best flight deals from Seattle to Heathrow for free. We help you search and compare prices from hundreds of airlines for the right flight just for you.

Question 27

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

Accepted Answer

Users can book flights with no change fees policies with our dedicated filters. Book flights from Seattle to Heathrow flexibly with Cheapflights today.

Question 28

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

Accepted Answer

Yes, Cheapflights offers price alerts on Seattle to Heathrow flights so you can book your travel at the perfect time. Price Alerts can be enabled by clicking the bell icon next to the flight deals above and providing your email address where you want to receive the alerts.

Round-trip from	C$ 708
One-way from	C$ 357
Popular in	June
Cheapest in	March
Average price	C$ 1,365
Good round-trip deal	C$ 969 or less
Good one-way deal	C$ 586 or less

Airline	Cheapest	Average	Flexibility	On-time
Icelandair	CheapestC$ 571	AverageC$ 757	FlexibilityNo cancel fee	On-time76%	Search Icelandair flights
Iberia	CheapestC$ 718	AverageC$ 864	FlexibilityNo cancel fee	On-time77%	Search Iberia flights
Virgin Atlantic	CheapestC$ 787	AverageC$ 990	FlexibilityNo cancel fee	On-time72%	Search Virgin Atlantic flights
British Airways	CheapestC$ 819	AverageC$ 1,123	FlexibilityNo cancel fee	On-time70%	Search British Airways flights

Cheap flights from Seattle to London Heathrow Airport from C$ 357

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 14/9. Fares are subject to change and may not be available on all flights or dates of travel.

Cheapflights Tip: The best prices from Seattle/Tacoma Intl to London Heathrow are usually found in March or April, booked 32 days in advance, depart on a Sunday or Thursday and return on a Tuesday

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Find flight deals from Seattle to Heathrow

Cheapest flights from Seattle to HeathrowExplore the most affordable flight options available from Seattle to Heathrow. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 29 July 2025.

Explore the most affordable flight options available from Seattle to Heathrow. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 29 July 2025.

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Use the filters below to find and compare flights from Seattle to London Heathrow Airport that are best for you.

Best time to book a flight from Seattle to Heathrow

Have a flexible travel schedule? Discover the best time to fly to Heathrow from Seattle with our price prediction graph.

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

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

Use this chart to determine the optimal time to book a round-trip flight from Seattle to Heathrow. Price data was last updated on 25 July 2025.

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

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

Find hourly flight availability from Seattle to Heathrow. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated 29 July 2025.

Weekly flight availability from Seattle to London Heathrow Airport

Explore weekly flight availability from Seattle to Heathrow. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated 29 July 2025.

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

What’s the top layover airport for flights from Seattle to London Heathrow Airport?

Share of one-stop round-trip flights from Seattle to London Heathrow Airport chosen by Cheapflights users in the past 12 months, using the same layover each way.

What’s the cheapest layover airport for flights from Seattle to London Heathrow Airport?

Average round-trip fare for 1-stop flights from Seattle to London Heathrow Airport, chosen by Cheapflights users in the past 12 months, with the same layover each way.

What’s the fastest layover option from Seattle to London Heathrow Airport?

Shortest average travel time for 1-stop one-way flights from Seattle to London Heathrow Airport, based on itineraries clicked by Cheapflights users over the past 12 months, grouped by layover airport.

Which airport typically offers the quickest layover for flights from Seattle to London Heathrow Airport?

Average layover duration for 1-stop one-way flights from Seattle to London Heathrow Airport, chosen by Cheapflights users in the last 12 months, grouped by stopover airport.

Reviews of airlines servicing Heathrow

Read through reviews of airlines operating flights from Seattle to London Heathrow Airport, such as Delta,KLM, andAustrian Airlines. Reviews also offer insight into each airline's entertainment options, comfort, food, crew/service, and boarding process.

Related info for your journey

Find useful and relevant information for your journey from Seattle to Heathrow. 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 from for flights from Seattle to London Heathrow?

What are the cheapest airlines flying from Seattle to London Heathrow Airport round-trip?

What are the cheapest airlines to fly from Seattle to London Heathrow Airport one-way?

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

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

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

How can I find direct flights from Seattle to Heathrow?

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

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

Travelling to a place near London Heathrow Airport?

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Alternative routes for Seattle to Heathrow

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Top 4 airlines flying from Seattle to Heathrow

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How does Cheapflights help users find flights from Seattle to Heathrow?

Why should you use Cheapflights to find cheap flight tickets from Seattle to Heathrow?

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

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

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Cheapest flights from Seattle to Heathrow
Explore the most affordable flight options available from Seattle to Heathrow. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 29 July 2025.