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Cheap flights from Washington, D.C. Dulles Intl Airport to Seattle from £118

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 26/8. Fares are subject to change and may not be available on all flights or dates of travel.
IAD — SEA
22 Jun — 29 Jun1
1 adult
1 adult, Economy, 0 bags

Cheap flight deals from Dulles Intl to Seattle

Enter your travel dates to find the best prices.

Cheapest flights from Dulles Intl to Seattle
Explore the most affordable flight options available from Dulles Intl to Seattle. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 23 May 2026.

Mon 13/719:53
IAD
-
SEA
1 stop16h 26m
Alaska Airlines
Wed 22/722:43
SEA
-
IAD
Nonstop4h 56m
Alaska Airlines
Deal found 21/5£231
Wed 26/817:15
IAD
-
SEA
1 stop8h 30m
United Airlines
Mon 31/823:00
SEA
-
IAD
1 stop7h 28m
United Airlines
Deal found 22/5£232
Tue 21/717:42
IAD
-
SEA
1 stop9h 02m
United Airlines
Tue 28/723:20
SEA
-
IAD
Nonstop5h 02m
United Airlines
Deal found 21/5£232
Mon 10/819:53
IAD
-
SEA
1 stop16h 26m
Alaska Airlines
Wed 26/820:51
SEA
-
IAD
1 stop18h 23m
Alaska Airlines
Deal found 18/5£234
Fri 25/907:00
IAD
-
SEA
Nonstop5h 37m
Alaska Airlines
Mon 5/1020:04
SEA
-
IAD
1 stop18h 49m
Alaska Airlines
Deal found 20/5£235
Tue 14/717:55
IAD
-
SEA
Nonstop5h 51m
United Airlines
Tue 28/723:20
SEA
-
IAD
Nonstop5h 02m
United Airlines
Deal found 20/5£237
Mon 13/707:00
IAD
-
SEA
Nonstop5h 45m
Delta
Thu 16/716:00
SEA
-
IAD
Nonstop5h 03m
Delta
Deal found 18/5£238
Tue 14/717:55
IAD
-
SEA
Nonstop5h 51m
United Airlines
Wed 22/723:20
SEA
-
IAD
Nonstop5h 02m
United Airlines
Deal found 21/5£239
Sun 16/806:30
IAD
-
SEA
1 stop8h 14m
United Airlines
Tue 25/813:57
SEA
-
IAD
1 stop7h 47m
United Airlines
Deal found 21/5£240
Thu 17/919:47
IAD
-
SEA
1 stop16h 33m
Alaska Airlines
Sat 26/908:30
SEA
-
IAD
Nonstop5h 13m
Alaska Airlines
Deal found 18/5£242
Wed 15/707:00
IAD
-
SEA
Nonstop5h 45m
Delta
Thu 23/716:00
SEA
-
IAD
Nonstop5h 03m
Delta
Deal found 20/5£243
Thu 11/606:33
IAD
-
SEA
1 stop8h 24m
United Airlines
Wed 17/608:00
SEA
-
IAD
Nonstop5h 09m
United Airlines
Deal found 21/5£243

Find flight deals from Dulles Intl to Seattle

Discover tips and strategies to find the most affordable flight options for your journey from Dulles Intl (IAD) to Seattle (SEA). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated 23 May 2026.

Round-trip from

£231

One-way from

£118

Popular in

June

Cheapest in

January

Average price

£337
Alaska Airlines
  • Alaska Airlines
  • 13/7-22/7
  • 1 total stop
  • 21h 22m total
  • Washington, D.C. to Seattle
Search Deals
United Airlines
  • United Airlines
  • 8/9
  • 1 total stop
  • 8h 54m total
  • Washington, D.C. to Seattle
Search Deals
Highest demand for flights based on searches. 16% potential increase in price (£41 potential increase over avg. return price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease (£6 potential savings vs. average return price).
Search Deals
Average for round-trip flights in May 2026
Search Deals

Cheapflights Fare Finder

 
Customise your flight search to find flights from Dulles Intl to Seattle that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 858,174 searches. Data last updated 23 May 2026.
Use the filters below to find and compare flights from Washington, D.C. Dulles Intl Airport to Seattle that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest return flight

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Tue 14/7

19:53-09:19

1 stop16h 26m

Seattle/Tacoma Intl

Tue 21/7

21:04-18:45

1 stop18h 41m

£249

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Mon 13/7

19:53-09:19

1 stop16h 26m

Seattle/Tacoma Intl

Wed 22/7

06:21-18:45

1 stop9h 24m

£249

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 20/8

07:00-09:37

Nonstop5h 37m

Seattle/Tacoma Intl

Mon 24/8

19:50-18:14

1 stop19h 24m

£257
Fastest return journey

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Mon 10/8

07:10-09:55

Nonstop5h 45m

Seattle/Tacoma Intl

Fri 21/8

15:58-23:59

Nonstop5h 01m

£258

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Fri 9/10

07:05-10:05

Nonstop6h 00m

Seattle/Tacoma Intl

Mon 12/10

15:55-23:51

Nonstop4h 56m

£266

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 27/8

19:35-09:20

1 stop16h 45m

Seattle/Tacoma Intl

Sat 29/8

21:35-05:40

Nonstop5h 05m

£275

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 12/8

15:40-22:45

1 stop10h 05m

Seattle/Tacoma Intl

Tue 22/9

08:10-16:16

Nonstop5h 06m

£279

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 27/8

07:10-09:55

Nonstop5h 45m

Seattle/Tacoma Intl

Mon 31/8

11:25-23:51

1 stop9h 26m

£287

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 4/7

06:00-12:58

1 stop9h 58m

Seattle/Tacoma Intl

Sat 11/7

16:00-00:03

Nonstop5h 03m

£287

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 8/7

19:49-09:19

1 stop16h 30m

Seattle/Tacoma Intl

Tue 21/7

09:13-17:11

Nonstop4h 58m

£290

Flights are sorted by cheapest return flights first.

Deals found on 22/5

Showing 1-10 of 23 resultsSorted by cheapest first
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Best time to book a flight from Dulles Intl to Seattle

Have a flexible travel schedule? Discover the best time to fly to Seattle from Dulles Intl with our price prediction graph.
Estimated return price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from Washington, D.C. Dulles Intl Airport to Seattle

How far ahead should I book a flight from Washington, D.C. Dulles Intl Airport to Seattle?

The best time to book flights from Washington, D.C. Dulles Intl Airport to Seattle is 35 days before your desired departure date. The cost of your flight will likely increase significantly if you book two weeks in advance of your flight.

What is the cheapest month to book a flight from Washington, D.C. Dulles Intl Airport to Seattle?

Currently, January is the cheapest month in which you can book a flight from Washington, D.C. Dulles Intl Airport to Seattle (average of £172). Flying from Washington, D.C. Dulles Intl Airport to Seattle in June is currently the most expensive (average of £355). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

What is the cheapest time of day to fly from IAD to SEA?

Find hourly flight availability from Dulles Intl to Seattle. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated 23 May 2026.

When flying from Washington, D.C. Dulles Intl Airport to Seattle, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.

How much does it cost for a return flight from Washington, D.C. Dulles Intl Airport to Seattle?

Related info for your journey

Find useful and relevant information for your journey from Dulles Intl to Seattle. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airport do you fly into for flights to Seattle from Washington, D.C. Dulles Intl?

    Located just 11.4 mi from the city center, Seattle/Tacoma Intl is the airport most travelers will use when flying to Seattle from Washington, D.C. Dulles Intl. Booking flights from Washington, D.C. Dulles Intl to Seattle/Tacoma Intl (SEA) should be relatively easy as there are 18 daily inbound flights from Washington, D.C. Dulles Intl from 0 different airlines.

  • How long is the flight from Washington, D.C. Dulles Intl Airport to Seattle?

    Alaska Airlines and Delta can get you from Washington, D.C. Dulles Intl Airport to Seattle in just under 5h 45m. Your travel time can differ by up to 10h 41m. The distance from Washington, D.C. Dulles Intl Airport to Seattle is about 2299 mi. When browsing for deals, the options you’ll see will be for both direct flights and flights with stops.

  • What are the most reliable airlines from Washington, D.C. Dulles Intl Airport to Seattle?

    The top 3 most reliable airlines when flying from Washington, D.C. Dulles Intl Airport to Seattle are Lufthansa (92%), Japan Airlines (84%) and Austrian Airlines (83%).

  • Can I find deals for flights from Dulles Intl to Seattle that include hotel bookings?

    Yes. In addition to deals on Dulles Intl to Seattle flights, Cheapflights offers holiday packages that include both flights and hotel.

  • How can I find direct flights from Dulles Intl to Seattle?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Dulles Intl to Seattle.

  • Can I find deals for business class flights from Dulles Intl to Seattle?

    Yes. Cheapflights offers flight deals from Dulles Intl to Seattle by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from Washington, D.C. Dulles Intl Airport to Seattle?

    Currently, January is the cheapest month in which you can book a flight from Washington, D.C. Dulles Intl Airport to Seattle (average of £172). Flying from Washington, D.C. Dulles Intl Airport to Seattle in June is currently the most expensive (average of £355). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

Travelling to a place near Seattle?

Book flights to Seattle if you plan to visit one of these locations
Tacoma
Federal Way
SeaTac

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When you search for this flight from Dulles Intl to Seattle, Cheapflights searches on 900+ travel sites to save you time finding great flight deals online. Additionally, we offer filter features so you can choose a preferred cabin class or airline, see different price ranges, and much more so you can book the flight for you.

Why should you use Cheapflights to find cheap flight tickets from Dulles Intl to Seattle?

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Can Cheapflights find flights from Dulles Intl to Seattle with no change fees?

Need flexible booking options for your flight to Seattle from Dulles Intl? Don’t worry, Cheapflights have you covered. Use our search filter to only show flights with no change fees.

Can Cheapflights notify me if prices for flights from Dulles Intl to Seattle become cheaper?

Yes, Cheapflights offers price alerts on Dulles Intl to Seattle flights so you can book your travel at the perfect time. Price Alerts can be enabled by clicking the bell icon next to the flight deals above and providing your email address where you want to receive the alerts.

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