Cheap flights from Seattle to London from C$ 450

The month of January is, on average, the cheapest month to fly to London Heathrow Airport from Seattle, with most prices found around C$ 909. If you aren’t able to travel to London Heathrow Airport 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$ 969.

According to our data, Wednesday is the cheapest day to fly to London Heathrow Airport from Seattle. The lowest ticket price found for a Wednesday departure recently was C$ 1,136. 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 Heathrow Airport for around C$ 1,217.

Our data shows that the cheapest Seattle to London Heathrow Airport flights are usually those with departure times in the evening. Our users have found flights to London Heathrow Airport in the evening for as low as C$ 1,125. In the afternoon is when there is more demand to fly to London Heathrow Airport, so prices are often more expensive at around C$ 1,164 per ticket.

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

You are more likely to see cheaper flights to London Heathrow Airport from Seattle when booking weeks ahead of your departure date. In general, you can expect to find flights to London Heathrow Airport for around C$ 1,175 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to London Heathrow Airport from Seattle for as low as C$ 1,022 on momondo.

There are 4 cabin classes available to choose from on Seattle to London Heathrow Airport 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 Heathrow Airport flight.

As of June 2026, prices for Seattle to London Heathrow Airport flights are approximately 35% cheaper when compared to flights at the same time last year.

British Airways, United Airlines, and Icelandair are the most popular carriers operating from Seattle/Tacoma Intl to London Heathrow

Virgin Atlantic, British Airways and Icelandair are the top three most popular airlines that fly to London Heathrow Airport 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 Heathrow Airport. Keep in mind that there are 3 different airlines that fly to London Heathrow Airport 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.

As of June 2026, there are 22 flights per day flying from Seattle to London Heathrow Airport. The most common time of day flights depart is 1:00p.m., with 72% of flights taking off in the evening.

The number of flights available between Seattle and London Heathrow Airport is 154 per week as of June 2026. The most frequent departure day is Tue, with 15% of weekly flights leaving on this day.