Cheap Flights from Seattle to London
Seattle (SEA) → London Heathrow (LHR) · 8–13 hours
Flights from Seattle (SEA) to London (LHR) are operated by Delta, United, American, British Airways, Lufthansa and Air France–KLM among others, with nonstop from the major gateways, or a single connection through a European hub. Total journey time is typically 8–13 hours. You depart from Seattle–Tacoma International (SEA) and arrive at London Heathrow (LHR), with Gatwick (LGW) as the value alternative.
| Departure airport | Seattle–Tacoma International (SEA) |
|---|---|
| Arrival airport | London Heathrow (LHR), with Gatwick (LGW) as the value alternative |
| Main airlines | Delta, United, American, British Airways, Lufthansa and Air France–KLM |
| Routing | Nonstop from the major gateways, or a single connection through a European hub |
| Journey time | 8–13 hours |
| When to book | Two to five months ahead for summer travel and six to eight weeks for the rest of the year; January and February are the cheapest months on this corridor by a clear margin |
Flying out of Seattle–Tacoma
Seattle–Tacoma is the Pacific Northwest's long-haul gateway and, like San Francisco, it is geographically well placed for anything crossing the Pacific. SEA's Asian and Gulf service means travellers from Bellevue, Redmond and the wider Eastside can usually reach India or Southeast Asia with one stop. The regional catchment is large — much of Oregon, Idaho and Alaska feeds through SEA — so booking early matters more here than the airport's size would suggest.
What to know before you fly to London
Entry requirements for US travellers
US citizens can visit the UK without a visa for short stays but now need an Electronic Travel Authorisation (ETA) before flying. It is applied for online and approval is usually quick, but it is a genuine requirement and airlines do check — apply through the UK government's official service, not a third-party site that charges a fee.
Best time to go
May, June and September give the best combination of weather and price. July and August are peak in both directions. January and February are the cheapest months of the year on the transatlantic corridor by a wide margin, and London is a perfectly good winter city.
Airports and arrival
Heathrow (LHR) has the widest schedule and the best onward connections. Gatwick (LGW) frequently carries lower fares on the same dates, and Stansted and Luton serve the budget European network — worth knowing if London is a stepping stone rather than the destination.
Baggage
Transatlantic economy now spans basic fares with carry-on only through to fares including two checked bags, at prices that are much closer together than they look. Matching the fare to how you actually pack is the whole game on this route.
Airlines from Seattle to London
Itineraries offer nonstop from the major gateways, or a single connection through a European hub.
Getting the best price to London
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Seattle to London — frequently asked questions
Fares on the Seattle–London route vary widely by season and how far ahead you book. We do not publish an estimate we have not measured for this pair; call our agents and they will quote the live consolidator fare for your dates.
Carriers on this route include Delta, United, American, British Airways, Lufthansa and Air France–KLM. Others serve it on one-stop itineraries, and the cheapest is not always a name you would expect — the lowest fare we have tracked here was on a carrier outside that list more than once. Itineraries offer nonstop from the major gateways, or a single connection through a European hub, and total journey time runs about 8–13 hours. Which carrier is cheapest changes with the season and the fare bucket rather than staying fixed, which is why we compare them all on every quote.
Plan on 8–13 hours from Seattle–Tacoma International (SEA) to London Heathrow (LHR), with Gatwick (LGW) as the value alternative, including time on the ground if your itinerary connects.
Book two to five months ahead for summer travel and six to eight weeks for the rest of the year; January and February are the cheapest months on this corridor by a clear margin.
Yes — this route has nonstop service, with nonstop from the major gateways, or a single connection through a European hub. Nonstop is not always the cheapest option: a one-stop itinerary on the same dates is frequently a few hundred dollars less, and on a journey of 8–13 hours that trade is worth pricing rather than assuming. Frequencies change by season, so call us for what is actually flying on your dates.
Sea-Tac (SEA) is the region's only significant airport, with Paine Field serving a handful of domestic routes. SEA's international departures and its domestic concourses are connected by an underground train, and the airport has grown faster than its footprint — the security wait is the part travellers underestimate.
Less than on the long-haul Asian routes, honestly — transatlantic economy is the most competitive market in aviation and the public fares are genuinely keen. Where we do earn our place is on the fare rules: basic economy on this corridor is restrictive in ways that are easy to miss, and the fare that includes a bag and a free change is frequently only a little more. SkyKaro's agents are reachable 24/7, and nothing is charged until an agent has confirmed the itinerary and the price with you.