Cheap flights from Seattle to London from £230

The cheapest month to fly to London from Seattle is in January. Flight prices, which tend to average around £242, 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 £321.

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 £519. When flying out on a Monday, the most expensive travel day of the week, you can expect to see flight prices from Seattle to London for around £680.

The cheapest time of day to fly to London is in the evening when flights can be purchased for as low as £592. Flights in the afternoon are often more expensive, with an average ticket price of £621.

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 £627 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 £546 on momondo.

There are 3 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 56% on your flight if you consider stops on a Seattle to London flight.

As of June 2026, prices for Seattle to London flights are approximately 13% more expensive when compared to flights at the same time last year.

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 128 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 £707.

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 June 2026, 20 flights take off from Seattle and land in London each day. The most common flight departure time for this route is 13:00, with 72% of daily flights taking off in the evening.

142 flights are operational weekly from Seattle to London as of June 2026. The most popular departure day for this route is Tue, with 16% of flights per week taking off on this day.