Cheap Flights from Seattle / Tacoma International to London Heathrow

Compare Seattle / Tacoma International to London Heathrow flight deals

Find the cheapest month or even day of the year to fly to London Heathrow

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Flight deals from Seattle / Tacoma International to London Heathrow

Looking for a cheap last-minute deal or the best round-trip flight from Seattle / Tacoma International to London Heathrow? Find the lowest prices on one-way and round-trip tickets right here.

London.$490 per passenger.Departing Mon, Dec 1, returning Tue, Dec 9.Round-trip flight with Icelandair.Outbound indirect flight with Icelandair, departing from Seattle / Tacoma International on Mon, Dec 1, arriving in London Heathrow.Inbound indirect flight with Icelandair, departing from London Heathrow on Tue, Dec 9, arriving in Seattle / Tacoma International.Price includes taxes and charges.From $490, select.

London.$505 per passenger.Departing Mon, Jan 5, returning Tue, Jan 20.Round-trip flight with Icelandair.Outbound indirect flight with Icelandair, departing from Seattle / Tacoma International on Mon, Jan 5, arriving in London Heathrow.Inbound indirect flight with Icelandair, departing from London Heathrow on Tue, Jan 20, arriving in Seattle / Tacoma International.Price includes taxes and charges.From $505, select.

London.$505 per passenger.Departing Thu, Dec 4, returning Mon, Jan 12.Round-trip flight with Icelandair.Outbound indirect flight with Icelandair, departing from Seattle / Tacoma International on Thu, Dec 4, arriving in London Heathrow.Inbound indirect flight with Icelandair, departing from London Heathrow on Mon, Jan 12, arriving in Seattle / Tacoma International.Price includes taxes and charges.From $505, select.

London.$508 per passenger.Departing Wed, Mar 11, returning Tue, Mar 17.Round-trip flight with Icelandair.Outbound indirect flight with Icelandair, departing from Seattle / Tacoma International on Wed, Mar 11, arriving in London Heathrow.Inbound indirect flight with Icelandair, departing from London Heathrow on Tue, Mar 17, arriving in Seattle / Tacoma International.Price includes taxes and charges.From $508, select.

London.$509 per passenger.Departing Thu, Jan 15, returning Sat, Feb 7.Round-trip flight with Icelandair.Outbound indirect flight with Icelandair, departing from Seattle / Tacoma International on Thu, Jan 15, arriving in London Heathrow.Inbound indirect flight with Icelandair, departing from London Heathrow on Sat, Feb 7, arriving in Seattle / Tacoma International.Price includes taxes and charges.From $509, select.

London.$516 per passenger.Departing Thu, Feb 19, returning Thu, Mar 5.Round-trip flight with Icelandair.Outbound indirect flight with Icelandair, departing from Seattle / Tacoma International on Thu, Feb 19, arriving in London Heathrow.Inbound indirect flight with Icelandair, departing from London Heathrow on Thu, Mar 5, arriving in Seattle / Tacoma International.Price includes taxes and charges.From $516, select.

London.$516 per passenger.Departing Sun, Feb 15, returning Thu, Feb 19.Round-trip flight with Icelandair.Outbound indirect flight with Icelandair, departing from Seattle / Tacoma International on Sun, Feb 15, arriving in London Heathrow.Inbound indirect flight with Icelandair, departing from London Heathrow on Thu, Feb 19, arriving in Seattle / Tacoma International.Price includes taxes and charges.From $516, select.

London.$523 per passenger.Departing Thu, Apr 9, returning Thu, Apr 16.Round-trip flight with Icelandair.Outbound indirect flight with Icelandair, departing from Seattle / Tacoma International on Thu, Apr 9, arriving in London Heathrow.Inbound indirect flight with Icelandair, departing from London Heathrow on Thu, Apr 16, arriving in Seattle / Tacoma International.Price includes taxes and charges.From $523, select.

Find the cheapest month to fly from Seattle / Tacoma International to London Heathrow

We’re always keeping an eye on fares, so you can find the best one in seconds. It looks like Seattle / Tacoma International to London Heathrow flights are currently cheapest in December.

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Direct flights from Seattle / Tacoma International to London Heathrow

Seattle / Tacoma International to London Heathrow: Alternative routes

Compare routes from Seattle / Tacoma International to London below. You may find an airport to fly into that's cheaper, faster, or easier than London Heathrow.

Seattle to London: Flight information

The things to know before you go.

Cheapest flight found	$490
Cheapest month to fly	December
Average flight time	9 hrs, 33 mins
Most popular airline	KLM
Average flights per week	128

Finding cheap flights from Seattle / Tacoma International to London Heathrow: Frequently asked questions

How much are round-trip flights from Seattle / Tacoma International to London Heathrow?

The best price we found for a round-trip flight from Seattle / Tacoma International to London Heathrow is $490. This is an estimate based on information collected from different airlines and travel providers over the last 4 days and is subject to change and availability.

How long does it take to fly from Seattle / Tacoma International to London Heathrow?

9 hours and 33 minutes is the average flight time from Seattle / Tacoma International to London Heathrow.

Which airlines fly direct from Seattle / Tacoma International to London Heathrow?

KLM, Delta and Virgin Atlantic fly direct from Seattle / Tacoma International to London Heathrow.

How many flights are there a week from Seattle / Tacoma International to London Heathrow?

There are 128 flights per week flying from Seattle / Tacoma International to London Heathrow, as of November 2025.

When is the cheapest time to fly from Seattle / Tacoma International to London Heathrow?

The cheapest month to fly from Seattle / Tacoma International to London Heathrow is usually December.

Which upcoming date is cheapest to fly from Seattle / Tacoma International Airport to London Heathrow Airport on?

After crunching the numbers on our flight calendar, we found that it's currently cheapest to fly from Seattle / Tacoma International Airport to London Heathrow Airport on Monday, December 1, 2025.

Can I get a direct flight from Seattle / Tacoma International Airport to London Heathrow Airport?

Yes – the average flight time is 9 hours and 33 minutes.

How can I find the best flight deal to London Heathrow?

We show every price from over 1,200 airlines and travel agents, comparing them all so you don’t have to. If you know you want to fly to London Heathrow but you’re not ready to book, set up a Price Alert. We’ll track prices for you, and let you know when they rise or fall.

When is the best time to book flights to London?

We crunched all the numbers in our flight calendar, and it looks like the cheapest time to book a flight to London is around 40 days in advance, so don’t leave your flight to the last minute.

Which is the cheapest airline to fly with from Seattle / Tacoma International Airport to London Heathrow?

Currently, Icelandair and Air France offer the cheapest flight tickets to London Heathrow.

Flying from Seattle-Tacoma International Airport (SEA) to London Heathrow Airport (LHR): what you need to know

The average duration of a direct flight from Seattle-Tacoma International Airport to London Heathrow Airport is 9 hours 25 minutes.
London's timezone is UTC+0, which makes London seven hours ahead of Seattle.
Take your pick of 37 weekly Seattle-Tacoma International Airport to London Heathrow Airport flights. The 13:30 departure with British Airways is the earliest flight you can take. Delta Air Lines operates the last service of the day at 21:20.
Your SEA to LHR flight won't wait if you're running late, so be at the airport on time. Arrive up to one hour in advance for domestic flights and two hours ahead when you're traveling internationally.
You'll likely experience bigger queues in popular months like July. Arriving up to four hours ahead of international flights and two hours for domestic departures is a wise move.
With direct flights from Seattle-Tacoma International Airport to London Heathrow Airport operated by a number of airlines, getting to London (and then other destinations in United Kingdom) is a breeze. You can travel nonstop with:
British Airways has the highest passenger demand on this route.
Delta Air Lines tops the rankings as the most punctual carrier for SEA to LHR flights, with 81.71% of services arriving as scheduled.
We make it a cinch to book a flight with a stopover. To see all your options for tickets from Seattle-Tacoma International Airport to London Heathrow Airport, deselect 'Direct flights only.' Then, choose a flight with a stop long enough to tour your chosen city. Top stopovers between SEA and LHR include:
- Vancouver International Airport
- Portland International Airport
- Keflavik International Airport

How to find the cheapest flights from Seattle-Tacoma International Airport (SEA) to London Heathrow Airport (LHR)

$225 is the best price for a one-way Seattle-Tacoma International Airport to London Heathrow Airport flight. A return flight starts at $490. These prices can change depending on demand.
Don't leave things to the last moment. You're more likely to get cheap tickets from SEA to LHR if you book ahead. Airlines often offer some amazing early bird rates.
November is the cheapest month for flights from Seattle-Tacoma International Airport to London Heathrow Airport. If you'd like to fly at a different time of year, the 'Whole month' tool will give you the lowest prices for each month.
Landing cheap flights from SEA to LHR is easy with Price Alerts. Simply set up one of these automatic alerts and we'll get in touch when a new discounted fare appears.
Pick your preferred arrival and departure times, number of stops and airlines with the filters. Alternatively, sort your results by 'Cheapest' to see the best deals on flights from Seattle-Tacoma International Airport to London Heathrow Airport.

Handy information about Seattle-Tacoma International Airport (SEA)

Seattle-Tacoma International Airport maintains a strong on-time performance, making delays less likely. Departures from SEA touch down on schedule 81.27% of the time.
Central Seattle to Seattle-Tacoma International Airport is approximately 23 kilometers. Depending on traffic, it'll take about 20 minutes to get there if you're driving, ride-sharing or catching a cab.
Expect a journey time of about 55 minutes when using public transport.
Taking an early flight from Seattle-Tacoma International Airport to London Heathrow Airport? Avoid rushing to the airport (and sneak in some extra snooze time) by choosing one of these hotels near SEA:

Arriving at London Heathrow Airport (LHR)

Book a hotel near LHR if you have a late Seattle-Tacoma International Airport to London Heathrow Airport flight. Check in to one of these accommodation options and skip the long transfer after landing:
Follow your own route with a London Heathrow Airport rental car. Pick up a set of wheels from Surprice, U-Save or Green Motion and discover more of London and beyond.
To lock in the lowest price, book your vehicle from London Heathrow Airport about one week in advance.

Getting from London Heathrow Airport (LHR) to central London

London Heathrow Airport is approximately 31 kilometers from central London. The drive time takes around 55 minutes.
Traveling to the center by public transport takes about 1 hour.

When to fly to London Heathrow Airport (LHR)

It's time to choose your travel dates for your flight from Seattle-Tacoma International Airport to London Heathrow Airport. July is the busiest month to head to London. If you prefer a quieter vibe, go in February.
Lock in your flight from Seattle-Tacoma International Airport to London Heathrow Airport for July if you'd like to explore London during its warmest month. Expect temperatures of between 11ºC (52ºF) and 26ºC (79ºF).
Search for cheap tickets from SEA to LHR in January if you'd rather travel during cooler conditions. Temperatures are at their lowest then, ranging between 0ºC (32ºF) and 9ºC (48ºF) on average.

Explore more of United Kingdom

Birmingham is just one of the many cities in United Kingdom waiting to be explored once you've taken in the sights of London. Around 161 kilometers away to the north-west, well-known attractions include Cadbury World, The Library of Birmingham and National Sea Life Centre.
Bristol is another well-known destination in United Kingdom and is around 177 kilometers west of London. No journey is complete without a visit to Clifton Suspension Bridge, Cabot Tower and Brandon Hill Nature Park.