Seattle (SEA) to London (LHR) is about 4,786 miles (7,702 km), roughly 10 h 05 min of flying time. London is 8 hours ahead of Seattle all year.
When is the cheapest time to fly from Seattle to London?
Lowest round-trip fares found in recent searches for each month (7 to 14 day trips). Pick a cheap month, then confirm the live price.
Are there nearby airports that could be cheaper?
Fares at a neighboring airport are sometimes lower. Worth comparing on this route:
- PAEPaine Field a small commercial terminal in Everett, north of Seattle.
- LGWLondon Gatwick Airport south of London.
- STNLondon Stansted Airport northeast of London.
What do I need before flying to London?
This is an international trip, so you need a valid passport. Entry rules, visas and health requirements change, so check the official US State Department page before you book: United Kingdom travel information. US citizens also need a UK Electronic Travel Authorisation before flying; see our UK ETA guide.
Plan how you will stay connected; an eSIM is usually cheaper than your carrier's roaming plan. See travel services.
Stay connected in London
An eSIM gives you local data from the moment you land, usually far cheaper than roaming.
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Things to do in London
Popular attractions and tickets, most with free cancellation.
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Frequently asked questions
How far is Seattle from London by plane?
The great-circle distance between SEA and LHR is about 4,786 miles (7,702 km).
How long does it take to fly from Seattle to London?
About 10 h 05 min of flying time based on distance, if a nonstop flight operates. Actual schedules vary by airline and wind, and itineraries with connections take longer.
What is the time difference between Seattle and London?
London is 8 hours ahead of Seattle all year.
Distance and flying time are calculated from airport coordinates (OurAirports data) and a typical cruise speed; they are planning estimates, not schedules. Updated 2026-10-28.
