$129 Cheap United flights Washington (IAD) to Seattle (SEA)

Use the “Price (lowest to highest)” filter on Expedia to look for cheap United Airlines return flights from $257 from IAD to SEA. Affordable one-way tickets from $129 are also on offer.**These prices were available on Expedia within the past 7 days, for flights departing within the next year. Prices and availability are subject to change. Additional terms apply.

Browse for one-way or round-trip flights to Seattle in January or February. You could find an affordable fare with United Airlines during these off-peak times.

For cheap United Airlines fares from Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA), start searching one to three months before your intended departure. Securing domestic flights 34 to 86 days in advance could save you 25% compared to booking just 6 to 12 days ahead. The day you book can also impact what you pay. Sunday tends to be the most affordable, while Monday is often the most expensive for domestic flights. You can save 6% on average by booking your flight on a Sunday.**Ideal booking window recommendation is based on average round-trip ticket prices for January through November for 2024. Best day of the week to book recommendation is based on average round-trip ticket prices for January through October 2024. All data sourced from ARC’s global airline sales database.

United Airlines operates direct flights from Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA), with 7 weekly departures. Simply use the “Nonstop” and “Airline” filters while searching on Expedia to show all direct United Airlines flights to SEA.

On average, it takes 6h 1m to travel nonstop from Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA) with United Airlines.

The first flight from IAD to SEA with United Airlines departs at 5:30PM UTC-5. You’ll touch down at 8:31PM UTC-8. The last United Airlines flight of the day leaves at 5:30PM UTC-5 and arrives at 8:31PM UTC-8. With approximately 20% fewer cancellations for early and mid-morning departures, heading out early is often the smartest option.**Most reliable time of the day recommendation is based on January through August 2024 flight status data sourced from OAG’s global flight data platform.

Seattle - Tacoma Intl. Airport (SEA) is the primary Seattle gateway for United Airlines flights from Washington Dulles Intl. Airport (IAD).

A rewarding loyalty program and the ability to collect points through United Mileage Plus are the start of the reasons to jet off from IAD to SEA with United Airlines. Plus, when you join Expedia’s free One Key™ program, you can earn OneKeyCash™* in addition to any airline loyalty program earnings. It’s yours to use wherever your next trip takes you.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.

United Airlines usually flies Boeing 737-900 planes for flights from Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA). This airline also operates the Boeing 737-800 on this route. Keep in mind that aircraft type can change depending on operational reasons, so the plane you board might be different on the day you travel.

It’s usually possible to cancel or modify your flight, although there may be additional fees if your booking was made more than 24 hours ago. Need flexible options? Make use of our “No cancel fee” and “Changes included” filters to find flights that won’t penalize you if you need to adjust your plans. To update your booking, visit “Trips,” select your flight and click on “Manage Booking” for more details.