Plan to arrive at SEA at least two hours before your flight due to potentially long security lines.

Most accurate provider | Mytrip 3 stars |
|---|---|
Most trusted provider | Mytrip 3 stars |
Round-trip from | $561 (Mytrip) |
One-way from | $340 (Mytrip) |
Popular in | June |
Cheapest in | November |
Average price | $987 |
Good round-trip deal | $631 or less |
Good one-way deal | $366 or less |
Fly from
Fly to
Route
Depart
Return
Price
SeattleLondon
SEA - LHR
SEALHR
Seattle/Tacoma Intl
Fri 2/20
4:55 pm-10:30 am
Nonstop9h 35m
London Heathrow
Tue 2/24
11:45 am-11:40 am
1 stop31h 55m
SeattleLondon
SEA - LHR
SEALHR
Seattle/Tacoma Intl
Thu 2/19
6:25 pm-11:55 am
Nonstop9h 30m
London Heathrow
Mon 2/23
10:00 am-11:40 am
1 stop33h 40m
SeattleLondon
SEA - LTN
SEALTN
Seattle/Tacoma Intl
Sun 4/12
6:45 pm-9:40 pm
1 stop18h 55m
London Luton
Wed 4/22
6:15 am-4:59 pm
1 stop18h 44m
SeattleLondon
SEA - LHR
SEALHR
Seattle/Tacoma Intl
Thu 2/12
8:00 am-7:05 am
1 stop15h 05m
London Heathrow
Tue 2/17
6:30 am-11:40 am
1 stop13h 10m
SeattleLondon
SEA - LHR
SEALHR
Seattle/Tacoma Intl
Tue 2/17
6:25 pm-11:55 am
Nonstop9h 30m
London Heathrow
Sun 3/1
6:20 am-1:05 pm
1 stop14h 45m
SeattleLondon
SEA - LHR
SEALHR
Seattle/Tacoma Intl
Sun 2/8
9:55 am-11:50 am
1 stop17h 55m
London Heathrow
Wed 2/18
6:50 am-10:43 pm
2 stops23h 53m
SeattleLondon
SEA - LHR
SEALHR
Seattle/Tacoma Intl
Thu 2/12
5:45 am-11:50 am
1 stop22h 05m
London Heathrow
Thu 2/19
6:50 am-7:03 pm
2 stops20h 13m
SeattleLondon
SEA - LTN
SEALTN
Seattle/Tacoma Intl
Sun 3/1
8:10 am-7:55 pm
3 stops27h 45m
London Luton
Sun 3/8
8:50 pm-1:10 pm
2 stops23h 20m
SeattleLondon
SEA - LHR
SEALHR
Seattle/Tacoma Intl
Tue 2/10
9:55 am-11:50 am
1 stop17h 55m
London Heathrow
Tue 2/17
4:40 pm-1:20 pm
1 stop28h 40m
SeattleLondon
SEA - LTN
SEALTN
Seattle/Tacoma Intl
Sat 1/24
2:35 pm-4:05 pm
2 stops17h 30m
London Luton
Fri 2/6
5:50 am-5:00 pm
2 stops19h 10m
| 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 Accuracy2 stars | Trust Score*3 stars | |
| Price Accuracy2 stars | Trust Score*2 stars | |
| Price Accuracy3 stars | Trust Score*2 stars | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy2 stars | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*3 stars |
Booking 9 days in advance of your planned departure date is, on average, the best time to get cheap flights from Seattle to London. The general trend is that the closer you book to the departure date, the more expensive your flight will be.
Currently, May is the cheapest month in which you can book a flight from Seattle to London (average of $494). Flying from Seattle to London in June is currently the most expensive (average of $790). 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 Seattle to London is to remain as flexible as possible. Flights that are in the morning tend to be the most expensive. A flight in the afternoon could potentially save you up to 26% on airfare.
The most flights from SEA to LON are scheduled on a Saturday (21 on average). You will have fewer flight options on Thursday, which is when the least amount of flights are scheduled (9 on average).
Reykjavik (KEF) – chosen by Cheapflights users on 76% of 1-stop itineraries from Seattle to London on Cheapflights.
Reykjavik (KEF) is the most affordable 1-stop option, with an average round-trip price of $546.
Flights via Dublin (DUB) have the shortest average one-way travel time for 1-stop routes: 11h 35m.
Flights via Reykjavik (KEF) offer the fastest connection on this route, with an average layover time of 1h 51m.
About 16% of weekly flights between Seattle and London have experienced delays in the past year, with the average delay time being 123 minutes.
Historically, flights departing in the early afternoon are less likely to be delayed, whereas flights leaving at night tend to experience delays more often.
Tuesday tends to have the lowest number of delays on this route, whereas Sunday has historically faced a higher average of delays compared to other days of the week.
Over the last year, Virgin Atlantic have had the lowest number of delays on this route, with just 6% of flights being delayed.
Food
Overall
Boarding
Crew
Comfort
Entertainment
Reviews
Jim,Nov 2025
AVL - ATL
Food
Overall
Boarding
Crew
Comfort
Entertainment
Reviews
Jim,Nov 2025
AVL - ATL
Food
Overall
Boarding
Crew
Comfort
Entertainment
Reviews
Jim,Nov 2025
AVL - ATL
Food
Overall
Boarding
Crew
Comfort
Entertainment
Reviews
Jim,Nov 2025
AVL - ATL
Food
Overall
Boarding
Crew
Comfort
Entertainment
Reviews
Jim,Nov 2025
AVL - ATL
Food
Overall
Boarding
Crew
Comfort
Entertainment
Reviews
Jim,Nov 2025
AVL - ATL
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$465 | Average$859 | FlexibilityNo cancel fee | On-time77% | |
| Cheapest$481 | Average$651 | FlexibilityNo cancel fee | On-time76% | |
| Cheapest$500 | Average$695 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$517 | Average$822 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$532 | Average$755 | FlexibilityNo cancel fee | On-time77% | |
| Cheapest$543 | Average$782 | FlexibilityNo cancel fee | On-time70% | |
| Cheapest$547 | Average$822 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$553 | Average$965 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$556 | Average$694 | FlexibilityNo cancel fee | On-time76% | |
| Cheapest$561 | Average$835 | FlexibilityNo cancel fee | On-timeN/A |