Cheap flights from London to Seattle from $517

In general, February is the cheapest month to fly from London to Seattle. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $649. If you don’t want to visit Seattle in February, then you should wait until January to fly from London, when ticket prices are also cheap, with an average price of $668.

On average, the least expensive day to fly to Seattle from London is on a Monday. momondo users have found tickets for Monday departures for as low as $823. However, this price may fluctuate depending on the airline, the season, and holidays. On the other hand, Friday is the most expensive day to depart from London because it is more convenient for both business and leisure travelers. As a result, prices tend to be around $966.

Flying to Seattle from London at noon is the least expensive time of day to depart. momondo users have found prices as low as $832 when looking at flights departing at noon. Flights to Seattle are more costly in the afternoon, with an average ticket price of $928. Departure times in the afternoon fall within the peak daily travel times, which is why tickets can be more expensive.

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

You are more likely to see cheaper flights to Seattle from London when booking weeks ahead of your departure date. In general, you can expect to find flights to Seattle for around $791 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Seattle from London for as low as $706 on momondo.

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

You could potentially save up to 3% on your flight if you consider stops on a London to Seattle flight.

As of August 2026, prices for London to Seattle flights are approximately 31% cheaper when compared to flights at the same time last year.

United Airlines, American Airlines, and SWISS are the most popular carriers operating from London to Seattle/Tacoma Intl

British Airways, Virgin Atlantic and Delta are the top three most popular airlines that fly to Seattle from London according to our data. British Airways is the first choice among our users, with 35% of people opting to fly with this airline when traveling to Seattle. Keep in mind that there are 7 different airlines that fly to Seattle on a routine basis, so you have a few additional options to choose from.

Historically, on average around 11% of flights between London and Seattle have experienced a delay on any given week. The average delay length over the past 12 months has been 130 minutes.

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

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

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

Reykjavik (KEF) was the most common stop: 70% of momondo users choosing 1-stop flights on this route connected there.

Flights via Munich (MUC) offer the lowest average round-trip price of $689.

Flights connecting via Frankfurt am Main (FRA) have the shortest average one-way travel time: 13h 25m.

Frankfurt am Main (FRA) has the shortest average layover time for this route: 1h 23m.

The number of flights available between London and Seattle is 22 per day as of August 2026. The most frequent departure time is 9:00AM, with 52% of daily flights leaving in the afternoon.

As of August 2026, 159 flights take off from London and land in Seattle each week. The most common flight departure day for this route is Tue, with 15% of weekly flights taking off on this day.