For a smooth departure from Heathrow, ensure all liquids are in one small bag to avoid lengthy security checks.

Most accurate provider | eDreams 3 stars |
|---|---|
Most trusted provider | eDreams 3 stars |
Round-trip from | $609 |
One-way from | $530 (Cheapflightsfares) |
Popular in | July |
Cheapest in | January |
Average price | $853 |
Good round-trip deal | $793 or less |
Good one-way deal | $713 or less |
Fly from
Fly to
Route
Depart
Return
Price
LondonSeattle
STN - SEA
STNSEA
London Stansted
Mon 2/2
6:00 am-5:00 pm
2 stops19h 00m
Seattle/Tacoma Intl
Mon 2/16
2:35 pm-10:05 pm
2 stops23h 30m
LondonSeattle
LHR - SEA
LHRSEA
London Heathrow
Mon 2/2
2:55 pm-4:55 pm
Nonstop10h 00m
Seattle/Tacoma Intl
Sun 2/15
9:00 am-6:50 am
1 stop13h 50m
LondonSeattle
LCY - SEA
LCYSEA
London City
Tue 3/10
8:05 pm-12:35 pm
1 stop23h 30m
Seattle/Tacoma Intl
Tue 3/17
4:00 pm-5:20 pm
1 stop18h 20m
LondonSeattle
LHR - SEA
LHRSEA
London Heathrow
Tue 3/10
6:30 am-1:10 pm
1 stop13h 40m
Seattle/Tacoma Intl
Tue 3/17
8:00 am-7:30 am
2 stops40h 30m
LondonSeattle
LHR - SEA
LHRSEA
London Heathrow
Tue 1/13
11:55 am-9:47 pm
1 stop17h 52m
Seattle/Tacoma Intl
Wed 1/28
6:50 pm-12:20 pm
Nonstop9h 30m
LondonSeattle
LHR - SEA
LHRSEA
London Heathrow
Mon 4/20
9:50 am-11:35 am
Nonstop9h 45m
Seattle/Tacoma Intl
Fri 4/24
3:57 pm-2:25 pm
1 stop14h 28m
LondonSeattle
LHR - SEA
LHRSEA
London Heathrow
Thu 4/9
6:30 am-11:35 am
1 stop13h 05m
Seattle/Tacoma Intl
Mon 4/13
1:30 pm-9:50 am
1 stop12h 20m
LondonSeattle
LHR - SEA
LHRSEA
London Heathrow
Mon 4/20
9:50 am-11:35 am
Nonstop9h 45m
Seattle/Tacoma Intl
Fri 4/24
8:20 pm-1:45 pm
Nonstop9h 25m
LondonSeattle
LCY - SEA
LCYSEA
London City
Fri 1/30
9:20 am-10:43 pm
2 stops21h 23m
Seattle/Tacoma Intl
Mon 2/9
12:35 pm-5:05 pm
2 stops20h 30m
LondonSeattle
LCY - SEA
LCYSEA
London City
Sat 2/28
8:35 am-11:30 pm
2 stops22h 55m
Seattle/Tacoma Intl
Thu 3/5
12:36 pm-5:05 pm
2 stops20h 29m
| Provider | Price Accuracy | Trust Score* |
|---|---|---|
| Price Accuracy2 stars | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*1 star | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*2 stars | |
| Price Accuracy2 stars | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*1 star | |
| Price Accuracy1 star | Trust Score*3 stars |
To ensure you get the cheapest price possible for a flight from London to Seattle, you should look to book at least 90 days in advance of your intended travel date. The price of your flight may increase if you delay and leave booking until a week or so before departure.
Currently, March is the cheapest month in which you can book a flight from London to Seattle (average of $408). Flying from London to Seattle in August is currently the most expensive (average of $617). 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.
One of the essential ways to save on airfare from London to Seattle is to remain as flexible as possible. Flights that are in the evening tend to be the most expensive. A flight at noon could potentially save you up to 21% on airfare.
Travelers seeking maximum savings on their London to Seattle flight should consider departing on Monday mornings when fares are most often at their lowest. Friday afternoons flights should be avoided if possible as fares are typically the most expensive at this time.
The most flights from LON to SEA are scheduled on a Thursday (15 on average). You will have fewer flight options on Monday, which is when the least amount of flights are scheduled (10 on average).
Reykjavik (KEF) – chosen by Cheapflights users on 67% of 1-stop itineraries from London to Seattle on Cheapflights.
Reykjavik (KEF) is the most affordable 1-stop option, with an average round-trip price of $497.
Flights via Reykjavik (KEF) have the shortest average one-way travel time for 1-stop routes: 13h 05m.
Flights via Denver (DEN) offer the fastest connection on this route, with an average layover time of 1h 25m.
About 13% of weekly flights between London and Seattle have experienced delays in the past year, with the average delay time being 119 minutes.
Historically, flights departing in the evening are less likely to be delayed, whereas flights leaving in the early afternoon tend to experience delays more often.
Tuesday tends to have the lowest number of delays on this route, whereas Wednesday has historically faced a higher average of delays compared to other days of the week.
Over the last year, Delta have had the lowest number of delays on this route, with just 6% of flights being delayed.
Entertainment
Food
Boarding
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Reviews
Jim,Nov 2025
AVL - ATL
Entertainment
Food
Boarding
Comfort
Crew
Overall
Reviews
Jim,Nov 2025
AVL - ATL
Entertainment
Food
Boarding
Comfort
Crew
Overall
Reviews
Jim,Nov 2025
AVL - ATL
Entertainment
Food
Boarding
Comfort
Crew
Overall
Reviews
Jim,Nov 2025
AVL - ATL
Entertainment
Food
Boarding
Comfort
Crew
Overall
Reviews
Jim,Nov 2025
AVL - ATL
Entertainment
Food
Boarding
Comfort
Crew
Overall
Reviews
Jim,Nov 2025
AVL - ATL
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$418 | Average$899 | FlexibilityNo cancel fee | On-time76% | |
| Cheapest$553 | Average$749 | FlexibilityNo cancel fee | On-time70% | |
| Cheapest$574 | Average$772 | FlexibilityNo cancel fee | On-time72% | |
| Cheapest$575 | Average$833 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$589 | Average$854 | FlexibilityNo cancel fee | On-time71% |