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 | $551 (Cheapflightsfares) |
One-way from | $332 (Kiwi.com) |
Popular in | June |
Cheapest in | January |
Average price | $641 |
Good round-trip deal | $637 or less |
Good one-way deal | $364 or less |
Fly from
Fly to
Route
Depart
Return
Price
SeattleLondon
SEA - LTN
SEALTN
Seattle/Tacoma Intl
Wed 3/4
3:10 pm-6:40 pm
2 stops19h 30m
London Luton
Wed 3/11
7:30 pm-10:16 pm
2 stops33h 46m
SeattleLondon
SEA - LHR
SEALHR
Seattle/Tacoma Intl
Sun 3/8
7:20 am-8:35 am
1 stop18h 15m
London Heathrow
Fri 3/20
8:50 am-7:20 pm
1 stop17h 30m
SeattleLondon
SEA - LHR
SEALHR
Seattle/Tacoma Intl
Wed 3/11
9:05 pm-4:50 pm
1 stop12h 45m
London Heathrow
Tue 3/17
8:45 pm-7:20 pm
1 stop29h 35m
SeattleLondon
SEA - LTN
SEALTN
Seattle/Tacoma Intl
Fri 2/27
3:10 pm-8:10 pm
2 stops21h 00m
London Luton
Fri 3/6
8:50 pm-12:10 pm
2 stops23h 20m
SeattleLondon
SEA - LTN
SEALTN
Seattle/Tacoma Intl
Wed 2/25
3:10 pm-6:40 pm
2 stops19h 30m
London Luton
Wed 3/4
7:30 pm-10:16 pm
2 stops34h 46m
SeattleLondon
SEA - LHR
SEALHR
Seattle/Tacoma Intl
Tue 4/14
8:20 pm-1:45 pm
Nonstop9h 25m
London Heathrow
Tue 4/28
9:50 am-5:10 pm
1 stop15h 20m
SeattleLondon
SEA - LHR
SEALHR
Seattle/Tacoma Intl
Mon 3/23
7:50 pm-12:20 pm
Nonstop9h 30m
London Heathrow
Thu 4/16
12:00 pm-5:10 pm
1 stop13h 10m
SeattleLondon
SEA - LHR
SEALHR
Seattle/Tacoma Intl
Wed 1/28
4:45 pm-10:30 am
Nonstop9h 45m
London Heathrow
Tue 2/3
6:20 am-11:25 am
1 stop13h 05m
SeattleLondon
SEA - LHR
SEALHR
Seattle/Tacoma Intl
Sat 1/31
8:00 pm-11:50 am
1 stop31h 50m
London Heathrow
Tue 2/10
6:35 am-6:26 pm
2 stops19h 51m
SeattleLondon
SEA - LHR
SEALHR
Seattle/Tacoma Intl
Wed 3/4
1:38 pm-10:00 am
1 stop12h 22m
London Heathrow
Wed 3/11
6:20 am-2:05 pm
1 stop14h 45m
| 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 64 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 $493). Flying from Seattle to London in June is currently the most expensive (average of $791). 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.
Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Seattle to London as you normally would.
The most flights from SEA to LON are scheduled on a Monday (15 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (12 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.
Comfort
Boarding
Crew
Entertainment
Food
Overall
Reviews
Jim,Nov 2025
AVL - ATL
Comfort
Boarding
Crew
Entertainment
Food
Overall
Reviews
Jim,Nov 2025
AVL - ATL
Comfort
Boarding
Crew
Entertainment
Food
Overall
Reviews
Jim,Nov 2025
AVL - ATL
Comfort
Boarding
Crew
Entertainment
Food
Overall
Reviews
Jim,Nov 2025
AVL - ATL
Comfort
Boarding
Crew
Entertainment
Food
Overall
Reviews
Jim,Nov 2025
AVL - ATL
Comfort
Boarding
Crew
Entertainment
Food
Overall
Reviews
Jim,Nov 2025
AVL - ATL
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$465 | Average$859 | FlexibilityNo cancel fee | On-time77% | |
| Cheapest$480 | Average$639 | FlexibilityNo cancel fee | On-time76% | |
| Cheapest$500 | Average$711 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$517 | Average$827 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$532 | Average$755 | FlexibilityNo cancel fee | On-time77% | |
| Cheapest$541 | Average$779 | FlexibilityNo cancel fee | On-time70% | |
| Cheapest$547 | Average$824 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$553 | Average$980 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$556 | Average$693 | FlexibilityNo cancel fee | On-time76% | |
| Cheapest$560 | Average$833 | FlexibilityNo cancel fee | On-timeN/A |