Question 1

What is the cheapest time of day to depart on your flight to London Heathrow Airport?

Accepted Answer

According to our data, the cheapest time of day to fly to London Heathrow Airport is at midday. momondo users have found flights departing from Seattle to London Heathrow Airport at midday for as low as £545. Keep in mind that these prices may fluctuate based on what airline you choose and the time of year you plan to travel. If you have a flexible travel schedule, then try to avoid flying in the evening when prices are £636 on average. Flights to London Heathrow Airport from Seattle in the evening are generally more expensive because this time of day is more convenient for travellers’ schedules.

Question 2

What is the most punctual flight time for Seattle to London flights?

Accepted Answer

Generally, flights departing in the early afternoon tend to experience fewer delays. Flights departing in the evening have, in the past, seen delays more frequently in comparison.

Question 3

How often are flights from Seattle to London delayed?

Accepted Answer

Historically, on average around 15% of flights between Seattle and London have experienced a delay on any given week. The average delay length over the past 12 months has been 126 minutes.

Question 4

What is the cheapest airline that flies from Seattle/Tacoma Intl to London Heathrow?

Accepted Answer

Icelandair, Lufthansa, and KLM are the most popular carriers operating from Seattle/Tacoma Intl to London Heathrow

Question 5

How many flights depart from Seattle to London Heathrow Airport on average per week?

Accepted Answer

87 flights are operational weekly from Seattle to London Heathrow Airport as of December 2025. The most popular departure day for this route is Mon, with 17% of flights per week taking off on this day.

Question 6

How have Seattle to London Heathrow Airport flight prices changed over time?

Accepted Answer

As of December 2025, prices for Seattle to London Heathrow Airport flights are approximately 4% cheaper when compared to flights at the same time last year.

Question 7

What is the cheapest day to depart on your flight to London Heathrow Airport?

Accepted Answer

On average, the least expensive day to fly to London Heathrow Airport from Seattle is on a Tuesday. momondo users have found tickets for Tuesday departures for as low as £516. However, this price may fluctuate depending on the airline, the season, and holidays. Be sure to avoid booking your departure on a Sunday as prices are generally higher than usual. According to our data, the average ticket price to London Heathrow Airport on Sunday is £658.

Question 8

Can stopping save me money on Seattle to London Heathrow Airport flights?

Accepted Answer

No. A direct flight is the cheapest option for a flight between Seattle to London Heathrow Airport.

Question 9

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

Accepted Answer

In general, October is the cheapest month to fly from Seattle to London Heathrow Airport. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around £495. The month of March is another great option to travel to London Heathrow Airport, with average flight prices from Seattle averaging around £513.

Question 10

What is the cheapest Seattle/Tacoma Intl to London Heathrow flight route?

Accepted Answer

Fly from Seattle/Tacoma Intl to London Heathrow for the best Seattle/Tacoma Intl - London Heathrow flight prices

Question 11

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

Accepted Answer

You are more likely to see cheaper flights to London Heathrow Airport from Seattle when booking weeks ahead of your departure date. In general, you can expect to find flights to London Heathrow Airport for around £599 when searching weeks before you fly. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to London Heathrow Airport from Seattle for as low as £528 on momondo.

Question 12

Which airline has the best punctuality record on Seattle to London flights?

Accepted Answer

According to our data, Virgin Atlantic have had the fewest delays on this route over the last 12 months, with about 5% of their flights experiencing any sort of delay.

Question 13

How many flights depart from Seattle to London Heathrow Airport on average per day?

Accepted Answer

As of December 2025, 12 flights take off from Seattle and land in London Heathrow Airport each day. The most common flight departure time for this route is 16:00, with 61% of daily flights taking off in the afternoon.

Question 14

What day of the week experiences the fewest flight delays on this route?

Accepted Answer

Tuesday is statistically the day of the week that experiences the fewest delays on this flight route. Sunday has historically seen more delays on average compared to the rest of the week.

Question 15

What cabin class options are available on Seattle/Tacoma Intl to London Heathrow flights?

Accepted Answer

There are 3 cabin classes available to choose from on Seattle/Tacoma Intl to London Heathrow flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Question 16

When did momondo last update prices for flights from Seattle/Tacoma Intl Airport to London Heathrow Airport?

Accepted Answer

Prices for flights from Seattle/Tacoma Intl Airport to London Heathrow Airport are refreshed on a daily basis.

Question 17

How many operators does momondo search for flights from Seattle/Tacoma Intl Airport to London Heathrow Airport?

Accepted Answer

There are 2 operators available for flights from Seattle/Tacoma Intl Airport to London Heathrow Airport as of December 2025.

Question 18

How old do you have to be to fly from Seattle/Tacoma Intl Airport to London Heathrow Airport?

Accepted Answer

Although the minimum age for a child to fly alone is five, airlines that offer an unaccompanied minor (UMNR) service may have their own age limits, which could be impacted by factors such as flight length, timing, and layovers. It is recommended that you verify with the airline you are booking with for travel from Seattle/Tacoma Intl Airport to London Heathrow Airport.

Question 19

What documentation or ID do you need to fly to London Heathrow Airport?

Accepted Answer

The travel and health documents you'll need for your trip to London Heathrow Airport may differ based on your itinerary and personal situation. Typically, you should have several documents on hand, such as a national ID card or driver's license and a passport that is valid for six months after your intended arrival at London Heathrow Airport. It is always advisable to seek advice from your airline or a trusted third party, such as IATA.

Best price found	£310
Fastest flight time	9h 15m
Direct flights	Every day

Airline	Rating	Free Cancellation	Price
British Airways	PriceFrom £355	Free Cancellation	Rating 6.7 7,562 reviews		Search British Airways flights
Virgin Atlantic	PriceFrom £370	Free Cancellation	Rating 7.5 675 reviews		Search Virgin Atlantic flights

Cheap flights from Seattle to London from £259

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How to get the cheapest flight ticket from Seattle to London Heathrow Airport

Look no further. We've gone through all the searches for this route on momondo so you have the important information and insights to find the cheapest flight ticket for your trip

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

What is the cheapest day to depart on your flight to London Heathrow Airport?

What is the cheapest time of day to depart on your flight to London Heathrow Airport?

What is the cheapest Seattle/Tacoma Intl to London Heathrow flight route?

Fly from Seattle/Tacoma Intl to London Heathrow for the best Seattle/Tacoma Intl - London Heathrow flight prices

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

What cabin class options are available on Seattle/Tacoma Intl to London Heathrow flights?

There are 3 cabin classes available to choose from on Seattle/Tacoma Intl to London Heathrow flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Can stopping save me money on Seattle to London Heathrow Airport flights?

No. A direct flight is the cheapest option for a flight between Seattle to London Heathrow Airport.

How have Seattle to London Heathrow Airport flight prices changed over time?

As of December 2025, prices for Seattle to London Heathrow Airport flights are approximately 4% cheaper when compared to flights at the same time last year.

What is the cheapest airline that flies from Seattle/Tacoma Intl to London Heathrow?

Icelandair, Lufthansa, and KLM are the most popular carriers operating from Seattle/Tacoma Intl to London Heathrow

How often are flights from Seattle to London delayed?

Historically, on average around 15% of flights between Seattle and London have experienced a delay on any given week. The average delay length over the past 12 months has been 126 minutes.

What is the most punctual flight time for Seattle to London flights?

Generally, flights departing in the early afternoon tend to experience fewer delays. Flights departing in the evening have, in the past, seen delays more frequently in comparison.

What day of the week experiences the fewest flight delays on this route?

Tuesday is statistically the day of the week that experiences the fewest delays on this flight route. Sunday has historically seen more delays on average compared to the rest of the week.

Which airline has the best punctuality record on Seattle to London flights?

According to our data, Virgin Atlantic have had the fewest delays on this route over the last 12 months, with about 5% of their flights experiencing any sort of delay.

How many flights depart from Seattle to London Heathrow Airport on average per day?

As of December 2025, 12 flights take off from Seattle and land in London Heathrow Airport each day. The most common flight departure time for this route is 16:00, with 61% of daily flights taking off in the afternoon.

How many flights depart from Seattle to London Heathrow Airport on average per week?

87 flights are operational weekly from Seattle to London Heathrow Airport as of December 2025. The most popular departure day for this route is Mon, with 17% of flights per week taking off on this day.

When to book flights from Seattle to London Heathrow Airport

Cheap Seattle to London Heathrow Airport (SEA to LHR) flight deals and tips

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How far is Seattle/Tacoma Intl to London Heathrow by plane?

When did momondo last update prices for flights from Seattle/Tacoma Intl Airport to London Heathrow Airport?

How many operators does momondo search for flights from Seattle/Tacoma Intl Airport to London Heathrow Airport?

How old do you have to be to fly from Seattle/Tacoma Intl Airport to London Heathrow Airport?

What documentation or ID do you need to fly to London Heathrow Airport?

What is the most popular plane model from Seattle to London Heathrow Airport?

What is the most popular airline from Seattle to London Heathrow Airport?

Best airlines flying from Seattle to London Heathrow Airport

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