Seattle-Tacoma International (SEA) to Heathrow (LHR). Served by Delta, British Airways.
| Departure | Return | Price |
|---|---|---|
| 05/26/2026 | 06/01/2026 | $822 |
| 05/26/2026 | 06/02/2026 | $829 |
| 08/03/2026 | 08/12/2026 | $836 |
| 08/04/2026 | 08/12/2026 | $836 |
| 08/05/2026 | 08/12/2026 | $836 |
| 05/26/2026 | 06/04/2026 | $872 |
| 07/18/2026 | 07/23/2026 | $879 |
| 07/18/2026 | 07/26/2026 | $879 |
| 07/18/2026 | 07/27/2026 | $879 |
| 07/19/2026 | 07/26/2026 | $879 |
Based on current fares, August is the cheapest month to fly from Seattle to London, with average fares around $853 round trip (as low as $836).
See the full month-by-month and day-of-week price analysis
Best Time to Fly SEA → LHRDeparture date prices (economy, round trip). Green = cheap, red = expensive.
The cheapest month to fly from Seattle to London is August, with average round-trip fares around $853. Fares in August start as low as $836. The most expensive month is June, averaging $1019.
A nonstop flight from Seattle to London takes approximately 9h 30m.
Delta and British Airways fly from SEA to LHR. That's 2 airlines serving this route.
The cheapest flight from Seattle to London currently starts at $822 round trip in economy class.
The average round-trip flight price from Seattle to London is $1006 in economy class.
The distance is 4787 miles (7702 km). with a nonstop flight time of about 9h 30m. Airlines on this route include Delta, British Airways. The lowest fare currently available is $822 departing in May. The average round-trip fare is $1006.
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