Cheap flights from Portland to London from $297

The cheapest month to fly to London from Portland is in October. Flight prices, which tend to average around $648, are often lower during this time because this is during the off-season. The month of November is another great option to travel to London, with average flight prices from Portland averaging around $659.

The cheapest day to depart from Portland to London is on a Monday. Travelers who choose to depart for London on a Monday will often find tickets for as low as $832. If your travel schedule is flexible, try to avoid departing on a Saturday because tickets tend to average around $996. These prices are subject to change though, so be sure to set up a Price Alert for flights to London.

Flying to London from Portland in the afternoon is the least expensive time of day to depart. momondo users have found prices as low as $728 when looking at flights departing in the afternoon. Flights to London are more costly in the evening, with an average ticket price of $916. Departure times in the evening fall within the peak daily travel times, which is why tickets can be more expensive.

Fly from Portland to London Heathrow for the best Portland - London flight prices

You are more likely to see cheaper flights to London from Portland when booking weeks ahead of your departure date. In general, you can expect to find flights to London for around $861 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to London from Portland for as low as $757 on momondo.

There are 4 cabin classes available to choose from on Portland 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 6% on your flight if you consider stops on a Portland to London flight.

As of April 2026, prices for Portland to London flights are approximately 60% cheaper when compared to flights at the same time last year.

United Airlines, Delta, and SWISS are the most popular carriers operating from Portland to London

British Airways, Icelandair and American Airlines are the top three most popular airlines that fly to London from Portland according to our data. British Airways is the first choice among our users, with 66% of people opting to fly with this airline when traveling to London. Keep in mind that there are 13 different airlines that fly to London on a routine basis, so you have a few additional options to choose from.

Reykjavik (KEF) was the most common stop: 52% of momondo users choosing 1-stop flights on this route connected there.

Flights via Phoenix (PHX) offer the lowest average round-trip price of $538.

Flights connecting via Reykjavik (KEF) have the shortest average one-way travel time: 12h 37m.

Denver (DEN) has the shortest average layover time for this route: 1h 26m.

As of April 2026, 4 flights take off from Portland and land in London each day. The most common flight departure time for this route is 7:00PM, with 100% of daily flights taking off in the evening.

The number of flights available between Portland and London is 32 per week as of April 2026. The most frequent departure day is Thu, with 22% of weekly flights leaving on this day.