HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news
London

$348+ Cheap flights from Portland, ME (PWM) to London (LON)

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 4/3. Fares are subject to change and may not be available on all flights or dates of travel.
PWM — LON
Mar 22 — Mar 291
Sun 3/22
Sun 3/29
1 adult, Economy
We work with more than 300 partners to bring you better travel deals

Find cheap flights from Portland to London with Cheapflights

1. Tell us where you want to go

Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”

2. Select your favorite providers

We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.

3. Compare prices and book

Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.

Cheap flight deals from Portland to London

Cheapest flights from Portland to London
Explore the most affordable flight options available from Portland to London. Find the lowest fares from popular airlines and budget airlines, with prices last updated on February 20, 2026.

This Delta deal was found by Cheapflights users on 2/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/62:51 pm
PWM
-
LHR
1 stop14h 29m
Delta
Wed 5/139:55 am
LHR
-
PWM
2 stops19h 39m
Delta
Deal found 2/19$648
This United Airlines deal was found by Cheapflights users on 2/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/256:00 am
PWM
-
LHR
1 stop9h 40m
United Airlines
Fri 9/46:50 am
LHR
-
PWM
2 stops16h 37m
United Airlines
Deal found 2/18$651
This United Airlines deal was found by Cheapflights users on 2/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/63:39 pm
PWM
-
LHR
2 stops14h 01m
United Airlines
Wed 5/136:50 am
LHR
-
PWM
2 stops16h 33m
United Airlines
Deal found 2/19$652
This United Airlines deal was found by Cheapflights users on 2/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/243:15 pm
PWM
-
LHR
2 stops14h 25m
United Airlines
Fri 9/46:50 am
LHR
-
PWM
2 stops16h 37m
United Airlines
Deal found 2/18$656
This Booking.com deal was found by Cheapflights users on 2/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 3/286:00 am
PWM
-
LHR
2 stops34h 00m
Air Canada
Fri 4/102:05 pm
LHR
-
PWM
2 stops38h 23m
Air Canada
Deal found 2/17$658
This United Airlines deal was found by Cheapflights users on 2/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 3/193:44 pm
PWM
-
LHR
1 stop10h 36m
United Airlines
Thu 3/267:40 am
LHR
-
PWM
1 stop17h 31m
United Airlines
Deal found 2/19$660
This United Airlines deal was found by Cheapflights users on 2/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/64:45 pm
PWM
-
LHR
1 stop14h 00m
United Airlines
Mon 5/115:50 pm
LHR
-
PWM
2 stops29h 33m
United Airlines
Deal found 2/19$661
This United Airlines deal was found by Cheapflights users on 2/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/256:00 am
PWM
-
LHR
1 stop9h 40m
United Airlines
Wed 9/27:30 am
LHR
-
PWM
2 stops15h 57m
United Airlines
Deal found 2/18$663
This United Airlines deal was found by Cheapflights users on 2/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/243:15 pm
PWM
-
LHR
2 stops14h 25m
United Airlines
Wed 9/27:30 am
LHR
-
PWM
2 stops15h 57m
United Airlines
Deal found 2/18$668
This Orbitz deal was found by Cheapflights users on 2/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Orbitz is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 3/196:00 am
PWM
-
LHR
2 stops25h 20m
Air Canada
Thu 3/269:00 am
LHR
-
PWM
2 stops17h 51m
Air Canada
Deal found 2/19$669
This Kiwi.com deal was found by Cheapflights users on 2/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/110:57 am
PWM
-
LGW
1 stop18h 03m
Multiple Airlines
Sun 4/122:00 pm
LGW
-
PWM
1 stop24h 07m
Multiple Airlines
Deal found 2/19$835
This KAYAK deal was found by Cheapflights users on 2/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure KAYAK is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 2/273:10 pm
PWM
-
LGW
2 stops21h 40m
Multiple Airlines
Wed 3/46:40 pm
LGW
-
PWM
2 stops28h 45m
Multiple Airlines
Deal found 2/18$905

Find flight deals from Portland to London

Discover tips and strategies to find the most affordable flight options for your journey from Portland (PWM) to London (LON). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated February 20, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$648
(Delta)

One-way from

$348
(Cheapflightsfares)

Popular in

July

Cheapest in

October

Average price

$673
Provider with most accurate pricing for Portland-London (LON) flight deals.
Search Deals
Provider most trusted by Cheapflights users for Portland-London (LON) flights.
Search Deals
From Portland to London (LON)
Search Deals
One-way flight from Portland to London (LON)
Search Deals
Highest demand for flights based on searches. 19% potential increase in price ($203 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 4% potential price decrease ($37 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in February 2026
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Portland to London that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated February 20, 2026.
Use the filters below to find and compare flights from Portland to London that are best for you.

Fly from

Portland

Fly to

London

Route

Depart

Return

Price

PortlandLondon

PWM - LHR

PWMLHR

Portland

Wed 5/6

2:51 pm-10:20 am

1 stop14h 29m

London Heathrow

Wed 5/13

9:55 am-12:34 am

2 stops19h 39m

$648

PortlandLondon

PWM - LHR

PWMLHR

Portland

Wed 5/6

3:39 pm-10:40 am

2 stops14h 01m

London Heathrow

Wed 5/13

6:50 am-6:23 pm

2 stops16h 33m

$652

PortlandLondon

PWM - LHR

PWMLHR

Portland

Sat 3/28

6:00 am-8:00 pm

2 stops34h 00m

London Heathrow

Fri 4/10

2:05 pm-11:28 pm

2 stops38h 23m

$658

PortlandLondon

PWM - LHR

PWMLHR

Portland

Wed 5/6

4:45 pm-11:45 am

1 stop14h 00m

London Heathrow

Mon 5/11

5:50 pm-6:23 pm

2 stops29h 33m

$661

PortlandLondon

PWM - LHR

PWMLHR

Portland

Thu 3/19

11:30 am-6:40 am

2 stops15h 10m

London Heathrow

Thu 3/26

9:10 am-6:25 pm

1 stop13h 15m

$665

PortlandLondon

PWM - LHR

PWMLHR

Portland

Thu 3/19

6:00 am-11:20 am

2 stops25h 20m

London Heathrow

Thu 3/26

9:00 am-10:51 pm

2 stops17h 51m

$669

PortlandLondon

PWM - LHR

PWMLHR

Portland

Sat 3/28

7:08 pm-7:40 pm

1 stop20h 32m

London Heathrow

Fri 4/10

11:05 am-9:40 pm

1 stop15h 35m

$669

PortlandLondon

PWM - LHR

PWMLHR

Portland

Wed 5/6

2:51 pm-8:50 am

1 stop12h 59m

London Heathrow

Wed 5/13

9:20 am-11:18 pm

1 stop18h 58m

$677

PortlandLondon

PWM - LHR

PWMLHR

Portland

Wed 5/6

12:46 pm-12:05 pm

2 stops18h 19m

London Heathrow

Mon 5/11

11:45 am-12:34 am

2 stops17h 49m

$703

PortlandLondon

PWM - LGW

PWMLGW

Portland

Wed 5/6

6:00 am-1:10 pm

2 stops50h 10m

London Gatwick

Mon 5/11

7:00 am-11:36 pm

2 stops21h 36m

$835

Flights are sorted by cheapest round-trip flights first.

Deals found on 2/20

Showing 1-10 of 36 results
1
2
3
4

Compare providers for flights from Portland to London

Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.
Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from Portland to London in February.
ProviderPrice AccuracyTrust Score*
ExpediaPrice Accuracy1 starTrust Score*3 stars
FlightHubPrice Accuracy3 starsTrust Score*3 stars
AranGrantPrice Accuracy2 starsTrust Score*2 stars
OvagoPrice Accuracy2 starsTrust Score*3 stars

*The Trust Score is based on feedback from users after their booking experience. It measures overall satisfaction, helping us identify issues like hidden fees, problems during the ticketing process, and the quality of customer service. This score is our best indicator of the provider's quality and reliability.

  • Most accurate provider: When it comes to deals on Portland, Maine-London flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on Portland, Maine-London flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from Portland, Maine-London flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on Portland, Maine-London flights, Cheapflights users trust FlightHub the most. FlightHub has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for Portland, Maine-London flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.

Best time to book a flight from Portland to London

Have a flexible travel schedule? Discover the best time to fly to London from Portland with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from Portland to London

What is the cheapest month to book a flight from Portland, Maine to London?

Currently, August is the cheapest month in which you can book a flight from Portland, Maine to London (average of $311). Flying from Portland, Maine to London in June is currently the most expensive (average of $544). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

How much does it cost to fly round-trip from Portland, Maine to London?

Reviews of airlines servicing London

Get insights into the airlines that provide service to London. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to London. Reviews last updated February 20, 2026.
Get a feel of what it's like to fly with Delta, United Airlines, and American Airlines from Portland to London by reading reviews from past customers. Users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Delta
7.9
Good
8,228 reviews

Food

7.2

Overall

7.9

Comfort

7.9

Crew

8.5

Entertainment

7.8

Boarding

8.1

Reviews

1 / 20
6.0
Good

Jim,Nov 2025

AVL - ATL

The exit row seats without a seat in front are great for leg room but don’t have a fold out entertainment console so you’re forced to use the screen several feet in front of you (there is, at least, a remote). Best to bring a tablet loaded with entertainment or a book.
Delta
7.9
Good
8,228 reviews
Delta
7.9
Good
8,228 reviews

Food

7.2

Overall

7.9

Comfort

7.9

Crew

8.5

Entertainment

7.8

Boarding

8.1

Reviews

1 / 20
6.0
Good

Jim,Nov 2025

AVL - ATL

The exit row seats without a seat in front are great for leg room but don’t have a fold out entertainment console so you’re forced to use the screen several feet in front of you (there is, at least, a remote). Best to bring a tablet loaded with entertainment or a book.
United Airlines
7.4
Good
9,335 reviews
Delta
7.9
Good
8,228 reviews

Food

7.2

Overall

7.9

Comfort

7.9

Crew

8.5

Entertainment

7.8

Boarding

8.1

Reviews

1 / 20
6.0
Good

Jim,Nov 2025

AVL - ATL

The exit row seats without a seat in front are great for leg room but don’t have a fold out entertainment console so you’re forced to use the screen several feet in front of you (there is, at least, a remote). Best to bring a tablet loaded with entertainment or a book.
American Airlines
7.2
Good
11,334 reviews
Delta
7.9
Good
8,228 reviews

Food

7.2

Overall

7.9

Comfort

7.9

Crew

8.5

Entertainment

7.8

Boarding

8.1

Reviews

1 / 20
6.0
Good

Jim,Nov 2025

AVL - ATL

The exit row seats without a seat in front are great for leg room but don’t have a fold out entertainment console so you’re forced to use the screen several feet in front of you (there is, at least, a remote). Best to bring a tablet loaded with entertainment or a book.
JetBlue
7.2
Good
2,898 reviews
Delta
7.9
Good
8,228 reviews

Food

7.2

Overall

7.9

Comfort

7.9

Crew

8.5

Entertainment

7.8

Boarding

8.1

Reviews

1 / 20
6.0
Good

Jim,Nov 2025

AVL - ATL

The exit row seats without a seat in front are great for leg room but don’t have a fold out entertainment console so you’re forced to use the screen several feet in front of you (there is, at least, a remote). Best to bring a tablet loaded with entertainment or a book.

Related info for your journey

Find useful and relevant information for your journey from Portland to London. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airport do you fly from for flights from Portland to London?

    Portland (PWM) is the airport you will fly out of if you book a flight from Portland to London. You should not have trouble finding flights to London from Portland; the airport handles an average of 0 outbound flights to London per day. You should also have plenty of airline options to choose from since 1 airline has flights from the Portland airport to London. It is only a 2.9 mi journey to Portland (PWM) from Portland’s city center.

  • How long is the flight from Portland, Maine to London?

    There are many flights that can get you from Portland, Maine to London in 13h 52m. Fly via Delta, United Airlines, or KLM to get the fastest option. There are 3193 mi between Portland, Maine and London. This flight may include one or multiple stops.

  • What is the cheapest airline to fly from Portland, Maine to London round-trip?

    Flying on United Airlines is currently your cheapest option to London, with prices starting at $648. United Airlines is 20% cheaper than the average price of flights available within the next 90 days to this destination.

  • What are the most popular routes from Portland, Maine to London?

    Most travelers choose Portland - London Heathrow, Portland - London Gatwick or Portland - London City when deciding on the best route from Portland, Maine to London.

  • Can I find deals for flights from Portland to London that include hotel bookings?

    Yes. In addition to deals on Portland to London flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Portland to London?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Portland to London.

  • Can I find deals for business class flights from Portland to London?

    Yes. Cheapflights offers flight deals from Portland to London by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from Portland, Maine to London?

    Currently, August is the cheapest month in which you can book a flight from Portland, Maine to London (average of $311). Flying from Portland, Maine to London in June is currently the most expensive (average of $544). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

Traveling to a place near London?

Book flights to London if you plan to visit one of these locations
Ilford
Croydon
Hounslow
Southend-on-Sea
Harrow
Eastleigh
Gatwick
Dartford
Dover
Winchester
Orpington
Watford
Hayes
Borehamwood
Aylesbury
Chipping Norton
Kingston upon Thames
Eastbourne
Sutton
Slough

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Top airline flying from Portland to London

Discover the top airline that operate flights from Portland to London. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated February 20, 2026.
AirlineCheapestAverageFlexibilityOn-time
United AirlinesCheapest$648Average$818FlexibilityNo cancel feeOn-time69%

100% Free

Cheapflights is completely free to use, so you can start saving the moment you arrive.

Book with Flexibility

Our users can plan ahead with confidence and find flights with no change fees

Travel Smart

Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.