Great-circle route IAD ↔ SEA. Faint dots are other airports, for geographic context. Download this map — free to reuse with a link back to this page.
Frequencies below are per direction, from our most recent schedule sample. The two directions are not identical — that is normal on scheduled routes.
| Direction | Frequency | Days | Airlines |
|---|---|---|---|
| IAD → SEA Washington to Seattle |
43/wk | Daily | Alaska Airlines, Delta Air Lines, United Airlines |
| SEA → IAD Seattle to Washington |
48/wk | Daily | Alaska Airlines, Delta Air Lines, United Airlines |
Where a direction shows “—” we track it as an operating nonstop but hold no schedule sample for it — we would rather show nothing than guess.
In 2025, airlines reported 551,410 passengers on 3,883 flights between IAD and SEA — about 1,512 a day — filling 85% of the 647,825 seats flown. Alaska Airlines Inc. carried the most passengers (45%).
Source: US DOT T-100 segment reports — actual airline-reported traffic, scheduled service only, both directions combined. Cargo and charter flights excluded.
3 airlines fly the IAD–SEA nonstop, including Alaska Airlines, Delta Air Lines, United Airlines.
Recent scheduled departures on this route have used the Boeing 737-900, Boeing 737, Airbus A220-300, Boeing 737-800.
Aircraft assignments change by season and by time of day.
On a long east–west route like this one the two directions do not take the same time. Aircraft flying eastbound ride the mid-latitude jet stream and typically arrive earlier than the westbound leg, which flies into it. The difference is commonly 30 to 90 minutes on transatlantic and transpacific flights, and it varies by season. The estimate above does not model wind — treat it as a midpoint and check the airline's own timetable for the block time on your date.
The distance between Washington Dulles International Airport and Seattle Tacoma International Airport is 2,300 miles, or 3,701 kilometres.
| Great-circle distance | 2,300 mi |
| Kilometres | 3,701 km |
| Nautical miles | 1,999 nmi |
Measured airport to airport. The actual track is longer — aircraft follow airways, avoid restricted airspace and route around weather.
Yes. 3 airlines fly the route nonstop, with about 91 departures a week across both directions. The route is in our live nonstop dataset, last seeded 2026-07-07.
About 5h 01m in the air. That is a great-circle estimate from the 2,300-mile distance, not a scheduled block time — an airline's published time will differ by roughly 15 to 45 minutes depending on routing, winds and taxi.
About 43 a week from Washington to Seattle and 48 a week from Seattle to Washington, from our most recent schedule sample.
Alaska Airlines, Delta Air Lines, United Airlines.
In 2025, airlines reported 551,410 passengers on 3,883 scheduled flights between IAD and SEA — about 1,512 a day — filling 85% of the seats flown. Source: US DOT T-100 segment reports, both directions combined.
Recent scheduled departures have used the Boeing 737-900, Boeing 737, Airbus A220-300, Boeing 737-800. Assignments change by season and by time of day.
