Cheap Flights from Washington Dulles (IAD) to Seattle / Tacoma International (SEA)

Compare Washington Dulles to Seattle / Tacoma International flight deals

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Flight deals from Washington Dulles to Seattle / Tacoma International

Looking for a cheap last-minute deal or the best return flight from Washington Dulles Airport to Seattle / Tacoma International Airport? If you want to travel next month, return fares start from £246. Find the lowest prices on one-way and return tickets right here.

Seattle.£84 per passenger.Departing Fri, 28 Aug.One-way flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Washington Dulles on Fri, 28 Aug, arriving in Seattle / Tacoma International.Price includes taxes and charges.From £84, select.

Seattle.£88 per passenger.Departing Mon, 20 Jul.One-way flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Washington Dulles on Mon, 20 Jul, arriving in Seattle / Tacoma International.Price includes taxes and charges.From £88, select.

Seattle.£96 per passenger.Departing Tue, 8 Sep.One-way flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Washington Dulles on Tue, 8 Sep, arriving in Seattle / Tacoma International.Price includes taxes and charges.From £96, select.

Seattle.£103 per passenger.Departing Tue, 10 Nov.One-way flight with American Airlines.Outbound indirect flight with American Airlines, departs from Washington Dulles on Tue, 10 Nov, arriving in Seattle / Tacoma International.Price includes taxes and charges.From £103, select.

Seattle.£107 per passenger.Departing Mon, 17 Aug.One-way flight with Alaska Airlines.Outbound direct flight with Alaska Airlines departs from Washington Dulles on Mon, 17 Aug, arriving in Seattle / Tacoma International.Price includes taxes and charges.From £107, select.

Seattle.£108 per passenger.Departing Wed, 30 Sep.One-way flight with Alaska Airlines.Outbound direct flight with Alaska Airlines departs from Washington Dulles on Wed, 30 Sep, arriving in Seattle / Tacoma International.Price includes taxes and charges.From £108, select.

Seattle.£119 per passenger.Departing Thu, 1 Oct.One-way flight with American Airlines.Outbound indirect flight with American Airlines, departs from Washington Dulles on Thu, 1 Oct, arriving in Seattle / Tacoma International.Price includes taxes and charges.From £119, select.

Seattle.£148 per passenger.Departing Thu, 1 Oct.One-way flight with Alaska Airlines.Outbound direct flight with Alaska Airlines departs from Washington Dulles on Thu, 1 Oct, arriving in Seattle / Tacoma International.Price includes taxes and charges.From £148, select.

Seattle.£148 per passenger.Departing Tue, 10 Nov.One-way flight with Alaska Airlines.Outbound direct flight with Alaska Airlines departs from Washington Dulles on Tue, 10 Nov, arriving in Seattle / Tacoma International.Price includes taxes and charges.From £148, select.

Seattle.£150 per passenger.Departing Wed, 15 Jul.One-way flight with Delta.Outbound direct flight with Delta departs from Washington Dulles on Wed, 15 Jul, arriving in Seattle / Tacoma International.Price includes taxes and charges.From £150, select.

Seattle.£182 per passenger.Departing Tue, 15 Dec.One-way flight with Delta.Outbound direct flight with Delta departs from Washington Dulles on Tue, 15 Dec, arriving in Seattle / Tacoma International.Price includes taxes and charges.From £182, select.

Seattle.£182 per passenger.Departing Wed, 24 Feb.One-way flight with United.Outbound direct flight with United departs from Washington Dulles on Wed, 24 Feb, arriving in Seattle / Tacoma International.Price includes taxes and charges.From £182, select.

Seattle.£182 per passenger.Departing Sun, 24 Jan.One-way flight with Delta.Outbound direct flight with Delta departs from Washington Dulles on Sun, 24 Jan, arriving in Seattle / Tacoma International.Price includes taxes and charges.From £182, select.

Seattle.£183 per passenger.Departing Sun, 7 Mar.One-way flight with United.Outbound direct flight with United departs from Washington Dulles on Sun, 7 Mar, arriving in Seattle / Tacoma International.Price includes taxes and charges.From £183, select.

Seattle.£183 per passenger.Departing Sat, 1 May.One-way flight with United.Outbound direct flight with United departs from Washington Dulles on Sat, 1 May, arriving in Seattle / Tacoma International.Price includes taxes and charges.From £183, select.

Seattle.£189 per passenger.Departing Sun, 28 Jun.One-way flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Washington Dulles on Sun, 28 Jun, arriving in Seattle / Tacoma International.Price includes taxes and charges.From £189, select.

Find the cheapest month to fly from Washington Dulles to Seattle / Tacoma International

We’re always keeping an eye on fares, so you can find the best one in seconds. It looks like Washington Dulles to Seattle / Tacoma International flights are currently cheapest in August.

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Direct flights from Washington Dulles to Seattle / Tacoma International

Washington Dulles to Seattle / Tacoma International: Alternative routes

Compare routes from Washington Dulles to Seattle below. You may find an airport to fly into that's cheaper, faster, or easier than Seattle / Tacoma International.

Washington D.C. to Seattle: Flight information

The things to know before you go.

Cheapest flight found	£84
Cheapest month to fly	August
Average flight time	5 hrs, 49 mins
Most popular airline	Alaska Airlines
Average flights per week	213

Finding cheap flights from Washington Dulles to Seattle / Tacoma International: Frequently asked questions

How much are return flights from Washington Dulles to Seattle / Tacoma International?

The best price we found for a return flight from Washington Dulles to Seattle / Tacoma International is £184. This is an estimate based on information collected from different airlines and travel providers over the last 4 days and is subject to change and availability.

How long does it take to fly from Washington Dulles to Seattle / Tacoma International?

5 hours and 49 minutes is the average flight time from Washington Dulles to Seattle / Tacoma International.

Which airlines fly direct from Washington Dulles to Seattle / Tacoma International?

Alaska Airlines, Qatar Airways and United fly direct from Washington Dulles to Seattle / Tacoma International.

How many flights are there a week from Washington Dulles to Seattle / Tacoma International?

As of June 2026, there are 166 flights per week flying from Washington Dulles to Seattle / Tacoma International.

When is the cheapest time to fly from Washington Dulles to Seattle / Tacoma International?

The cheapest month to fly from Washington Dulles to Seattle / Tacoma International is usually August.

Which upcoming date is cheapest to fly from Washington Dulles Airport to Seattle / Tacoma International Airport on?

After crunching the numbers on our flight calendar, we found that it's currently cheapest to fly from Washington Dulles Airport to Seattle / Tacoma International Airport on Thursday, 20 August 2026.

Can I get a direct flight from Washington Dulles Airport to Seattle / Tacoma International Airport?

Yes – the average flight time is 5 hours and 49 minutes.

How can I find the best flight deal to Seattle / Tacoma International?

We show every price from over 1,200 airlines and travel agents, comparing them all so you don’t have to. If you know you want to fly to Seattle / Tacoma International but you’re not ready to book, set up a Price Alert. We’ll track prices for you, and let you know when they rise or fall.

When is the best time to book flights to Seattle?

We crunched all the numbers in our flight calendar and it looks like the cheapest time to book a flight to Seattle is around 40 days in advance, so don’t leave your flight to the last minute.

Which is the cheapest airline to fly from Washington Dulles Airport to Seattle / Tacoma International with?

Currently, Frontier Airlines and Delta offer the cheapest flight tickets to Seattle / Tacoma International.

Travelling from Washington Dulles Airport (IAD) to Seattle / Tacoma International Airport (SEA): what you need to know

The average time for a direct flight from Washington Dulles Airport to Seattle / Tacoma International Airport is 5 hours 50 minutes.
The timezone in Seattle is UTC-8, which is three hours behind Washington DC.
Flights from IAD to SEA start from 06:30 — the earliest with Alaska Airlines. The latest departure is at 22:14 with United Airlines. In total, you can take your pick of 35 weekly Washington Dulles Airport to Seattle / Tacoma International Airport flights.
Arriving two hours before an international flight and one hour ahead of a domestic departure are travel rules worth sticking to. Be at the airport with enough time to catch your IAD to SEA flight.
Travelling during a peak month such as July? School holidays and other popular periods can mean longer lines and delays at airport checkpoints. Play it safe and get there up to four hours ahead of international flights and two hours before domestic departures.
You'll find a variety of airlines offering direct flights from Washington Dulles Airport to Seattle / Tacoma International Airport. When you're ready to start your Seattle holiday, let one of these carriers transport you to this unmissable part of the United States:
Alaska Airlines tops the list for bookings on this route.
United ranks as the top on-time carrier for IAD to SEA flights, with 83.65% of services reaching their destination on schedule.
We make it a cinch to book a flight with a stopover. To see all your options for tickets from Washington Dulles Airport to Seattle / Tacoma International Airport, deselect 'Direct flights only.' Then, pick a flight offering a stop long enough to explore the city of your choice. Stopovers between IAD and SEA include:
- Chicago O'Hare International Airport
- Denver International Airport
- Detroit Wayne County Airport

How to find the cheapest flights from Washington Dulles Airport (IAD) to Seattle / Tacoma International Airport (SEA)

£84 is the best price for a one-way Washington Dulles Airport to Seattle / Tacoma International Airport flight. Return flights start at £184. These prices can change depending on demand and availability.
To score cheap tickets from IAD to SEA, reserve your journey one month before your planned departure.
June is the cheapest month for flights from Washington Dulles Airport to Seattle / Tacoma International Airport. If you prefer to travel at a different time of year, the 'Whole month' tool will show you the lowest prices across every month.
Picking up cheap flights from IAD to SEA is a cinch with Price Alerts. All you need to do is create one of these automatic alerts and we'll let you know when fares go down.
Tailor your trip with filters. Pick your preferred arrival and departure times, total journey duration and airlines. You can also sort the results by 'Cheapest,' 'Fastest' or 'Best' flights from Washington Dulles Airport to Seattle / Tacoma International Airport.

Handy information about Washington Dulles Airport (IAD)

IAD is located at 1 Saarinen Circle.
77% of flights leaving from Washington Dulles Airport reach their destination on schedule.
Central Washington DC to Washington Dulles Airport is around 40 kms (25 miles). Depending on traffic, it'll take you about 45 minutes to get there if you're ride-sharing, catching a taxi or driving.
The journey when using public transport usually takes 1 hour 10 minutes.
Get your break off to a leisurely start by staying near IAD. Whether you're taking an early flight from Washington Dulles Airport to Seattle / Tacoma International Airport or want to avoid feeling rushed, these hotels have you covered:

Arriving at Seattle / Tacoma International Airport (SEA)

Reserve a hotel close to SEA if you have a late Washington Dulles Airport to Seattle / Tacoma International Airport flight. Settle into one of these accommodation options and skip the long transfer:
Get on the fast track to adventure by picking up a Seattle / Tacoma International Airport rental car. Grab a set of wheels from Thrifty, Europcar or Budget and experience the lesser-explored corners of Seattle and beyond.
To secure the lowest price, book your ride from Seattle / Tacoma International Airport about one week before your trip.

When to fly to Seattle / Tacoma International Airport (SEA)

It's time to pick your trip dates for your flight from Washington Dulles Airport to Seattle / Tacoma International Airport. July is the most popular month to visit Seattle. If you like a quieter vibe, go in March.
The warmest month in Seattle is August, with temperatures ranging between 12ºC and 28ºC. Book your flights from Washington Dulles Airport to Seattle / Tacoma International Airport in this month if you like this kind of weather.
If you want to travel in cooler conditions, search for a cheap ticket from IAD to SEA in February. Average temperatures are between -1ºC and 11ºC then.

Explore more of the United States

You've visited Seattle, now it's time to explore other corners of the United States. Journey about 241 kms (150 miles) south to Portland to tick off its top attractions. From Portland Japanese Garden to Peninsula Park Rose Garden and Beyond Van Gogh Portland, you've got a jam-packed schedule ahead.
Around 370 kms (230 miles) east of Seattle, Spokane is another favourite stop in the United States. No visit is complete without checking out Riverside State Park, Spokane Falls (Upper Falls) and Cathedral of Our Lady of Lourdes.