Cheap flights from Seattle to Dulles (SEA to IAD) from $551

Book at the right time: For domestic routes like Seattle to Dulles, the sweet spot is 3–5 weeks before departure. Booking too early can mean missing seat sales; too late means paying peak prices.

Shift your dates by a day or two: Mid-week departures (Tuesday–Wednesday) are almost always cheaper than weekend flights. Even shifting by one day can make a meaningful difference.

Direct flights are available: Direct flights take around 10h 17m and are worth it for convenience — but check if a one-stop flight is significantly cheaper before ruling it out.

Factor in baggage fees: Low-cost carriers on this route often advertise attractive base fares but charge separately for checked luggage. Always compare the all-in price — a $20 cheaper fare plus $50 baggage fee is no saving. Alaska Airlines and American Airlines may have different inclusions, so check each airline's fare conditions.

Search in private browsing: Some booking sites use cookies to track repeat searches and may show higher prices after multiple lookups. Use an incognito or private window — or just use Booked AI, which pulls live prices without any tracking markup.

The cheapest flights from Seattle to Dulles start from $551, with typical prices ranging from $551 to $739.

The typical flight time from Seattle to Dulles is approximately 10 hours and 17 minutes. Direct flights are available on this route.

Airlines operating this route include Alaska Airlines, American Airlines, Hawaiian Airlines.