Cheap flights from Seattle to London from C$ 451

In general, January is the cheapest month to fly from Seattle to London. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around C$ 453. If you aren’t able to travel to London during the month of January, then flying in February is also cheap. Prices for this month can be found on momondo for an average of C$ 602.

According to our data, Wednesday is the cheapest day to fly to London from Seattle. The lowest ticket price found for a Wednesday departure recently was C$ 1,138. Keep in mind that prices can always vary depending on your route and whether or not you are flying domestic or international. When flying out on a Thursday, the most expensive travel day of the week, you can expect to see flight prices from Seattle to London for around C$ 1,219.

Our most recent data shows that the best time of day to fly to London is in the evening. Flights from Seattle to London during this time can be as low as C$ 1,127. In the afternoon is when there is more demand to fly to London, so prices are often more expensive at around C$ 1,167 per ticket.

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 C$ 1,177 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to London from Seattle for as low as C$ 1,023 on momondo.

There are 4 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 2% 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.

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

Virgin Atlantic, British Airways and Icelandair 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 43% 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 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 has had the least delays on this route over the last 12 months, with about 6% of their flights experiencing any sort of delay.

20 flights are operational daily from Seattle to London as of June 2026. The most popular departure time for this route is 1:00p.m., with 72% of flights per day taking off in the evening.

As of June 2026, there are 142 flights per week flying from Seattle to London. The most common day of the week flights depart is Tue, with 16% of flights taking off on this day.