Cheap flights from Seattle to London from £210

The cheapest month to fly to London from Seattle is in January. Flight prices, which tend to average around £475, are often lower during this time because this is during the off-season. The month of February is another great option to travel to London, with average flight prices from Seattle averaging around £510.

Our data shows that Tuesday is the least expensive day to fly to London. Tickets to fly out on this day can be as low as £604. When flying out on a Sunday, the most expensive travel day of the week, you can expect to see flight prices from Seattle to London for around £825.

The cheapest time of day to fly to London is at midday when flights can be purchased for as low as £611. Flights in the evening are often more expensive, with an average ticket price of £704.

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

You are more likely to see cheaper flights to London from Seattle when booking weeks ahead of your departure date. In general, you can expect to find flights to London for around £632 when searching weeks before you fly. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to London from Seattle for as low as £579 on momondo.

There are 2 cabin classes available to choose from on Seattle to London 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 17% on your flight if you consider stops on a Seattle to London flight.

As of August 2026, prices for Seattle to London flights are approximately 21% cheaper when compared to flights at the same time last year.

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

Virgin Atlantic, British Airways and Alaska Airlines are the top three most popular airlines that fly to London from Seattle according to our data. Virgin Atlantic is the first choice among our users, with 58% of people opting to fly with this airline when travelling to London. Keep in mind that there are 3 different airlines that fly to London on a routine basis, so you have a few additional options to choose from.

Historically, on average around 14% 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 134 minutes.

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.

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

According to our data, Virgin Atlantic have had the fewest delays on this route over the last 12 months, with about 6% of their flights experiencing any sort of delay.

Frankfurt am Main (FRA) was the most common stop: 50% of momondo users choosing one-stop flights on this route connected there.

Flights via Frankfurt am Main (FRA) offer the lowest average return price of £690.

Flights connecting via Reykjavik (KEF) have the shortest average one-way travel time: 12h 15m.

Frankfurt am Main (FRA) has the shortest average stopover time for this route: 1h 25m.

As of August 2026, 23 flights take off from Seattle and land in London each day. The most common flight departure time for this route is 21:00, with 74% of daily flights taking off in the evening.

167 flights are operational weekly from Seattle to London as of August 2026. The most popular departure day for this route is Tue, with 15% of flights per week taking off on this day.