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Cheap flights from Washington, D.C. Dulles Intl Airport to Seattle from £90

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 12/5. Fares are subject to change and may not be available on all flights or dates of travel.
IAD — SEA
18 Apr — 25 Apr1
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 19 March 2026.

Tue 5/517:55
IAD
-
SEA
Nonstop5h 58m
United Airlines
Tue 12/508:10
SEA
-
IAD
Nonstop5h 12m
United Airlines
Deal found 16/3£149
Sat 2/507:10
IAD
-
SEA
Nonstop5h 48m
Alaska Airlines
Sat 9/515:55
SEA
-
IAD
Nonstop5h 14m
Alaska Airlines
Deal found 17/3£155
Tue 14/407:00
IAD
-
SEA
Nonstop5h 54m
Delta
Mon 20/422:40
SEA
-
IAD
1 stop10h 25m
Delta
Deal found 15/3£157
Tue 28/407:00
IAD
-
SEA
1 stop9h 15m
American Airlines
Tue 5/522:29
SEA
-
IAD
1 stop7h 20m
American Airlines
Deal found 14/3£164
Wed 22/411:04
IAD
-
SEA
1 stop10h 24m
Delta
Thu 7/522:35
SEA
-
IAD
1 stop10h 48m
Delta
Deal found 16/3£164
Wed 29/406:20
IAD
-
SEA
2 stops14h 25m
Southwest
Mon 4/513:55
SEA
-
IAD
1 stop7h 25m
Southwest
Deal found 16/3£168
Thu 9/407:00
IAD
-
SEA
Nonstop5h 53m
Alaska Airlines
Tue 28/415:55
SEA
-
IAD
Nonstop5h 14m
Alaska Airlines
Deal found 16/3£172
Fri 1/516:30
IAD
-
SEA
1 stop11h 25m
Southwest
Mon 11/506:30
SEA
-
IAD
2 stops14h 50m
Southwest
Deal found 16/3£173
Sat 25/407:00
IAD
-
SEA
Nonstop5h 54m
Delta
Mon 11/516:05
SEA
-
IAD
Nonstop5h 10m
Delta
Deal found 16/3£176
Wed 22/407:10
IAD
-
SEA
Nonstop5h 48m
Alaska Airlines
Sun 3/515:55
SEA
-
IAD
Nonstop5h 14m
Alaska Airlines
Deal found 16/3£179
Sat 25/409:00
IAD
-
SEA
Nonstop5h 47m
Alaska Airlines
Wed 29/421:41
SEA
-
IAD
Nonstop5h 09m
Alaska Airlines
Deal found 17/3£183
Fri 24/419:20
IAD
-
SEA
Nonstop5h 45m
Alaska Airlines
Mon 4/515:55
SEA
-
IAD
Nonstop5h 14m
Alaska Airlines
Deal found 16/3£186

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 19 March 2026.

Round-trip from

£149

One-way from

£90

Popular in

June

Cheapest in

January

Average price

£310

Good round-trip deal

£99 or less
United Airlines
  • United Airlines
  • 5/5-12/5
  • Nonstop
  • 11h 10m total
  • Washington, D.C. to Seattle
Search Deals
Delta
  • Delta
  • 12/5
  • Nonstop
  • 5h 44m total
  • Washington, D.C. to Seattle
Search Deals
Highest demand for flights based on searches. 12% potential increase in price (£30 potential increase over avg. return price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease (£5 potential savings vs. average return price).
Search Deals
Average for round-trip flights in March 2026
Search Deals
Price to beat on a round-trip flight from Washington, D.C. Dulles Intl to Seattle/Tacoma Intl.
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 19 March 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
Fastest return journey

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 25/4

06:00-10:32

1 stop7h 32m

Seattle/Tacoma Intl

Mon 11/5

16:05-00:15

Nonstop5h 10m

£157

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Tue 28/4

07:00-09:54

Nonstop5h 54m

Seattle/Tacoma Intl

Tue 5/5

06:00-17:57

1 stop8h 57m

£157

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Tue 28/4

17:30-23:35

1 stop9h 05m

Seattle/Tacoma Intl

Tue 5/5

09:20-23:40

2 stops11h 20m

£168

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 9/5

14:36-21:06

1 stop9h 30m

Seattle/Tacoma Intl

Sat 16/5

22:41-06:50

Nonstop5h 09m

£172

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 8/4

10:10-16:37

1 stop9h 27m

Seattle/Tacoma Intl

Wed 15/4

08:00-16:11

Nonstop5h 11m

£197

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 2/5

05:50-17:05

2 stops14h 15m

Seattle/Tacoma Intl

Sat 9/5

05:45-16:25

1 stop7h 40m

£231

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 2/5

17:55-20:53

Nonstop5h 58m

Seattle/Tacoma Intl

Sat 9/5

19:36-07:35

1 stop8h 59m

£239

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Mon 13/4

18:22-09:27

1 stop18h 05m

Seattle/Tacoma Intl

Mon 20/4

19:49-17:22

1 stop18h 33m

£243

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Tue 14/4

06:20-17:45

2 stops14h 25m

Seattle/Tacoma Intl

Mon 20/4

13:55-00:20

1 stop7h 25m

£261

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 14/5

19:37-19:04

1 stop26h 27m

Seattle/Tacoma Intl

Sun 17/5

23:30-07:34

Nonstop5h 04m

£271

Flights are sorted by cheapest return flights first.

Deals found on 13/3

Showing 1-10 of 21 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?

Use this chart to determine the optimal time to book a return flight from Dulles Intl to Seattle. Price data was last updated on 13 March 2026.

The best time to book flights from Washington, D.C. Dulles Intl Airport to Seattle is 36 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, February is the cheapest month in which you can book a flight from Washington, D.C. Dulles Intl Airport to Seattle (average of £89). Flying from Washington, D.C. Dulles Intl Airport to Seattle in September is currently the most expensive (average of £174). 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 19 March 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.

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 12 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?

    Delta, Southwest, and United Airlines can get you from Washington, D.C. Dulles Intl Airport to Seattle in just under 7h 32m. Your travel time can differ by up to 1h 58m. 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 Japan Airlines (87%), Air Tahiti Nui (87%) and Iberia (84%).

  • What are the cheapest flights from Washington, D.C. Dulles Intl Airport to Seattle?

    Looking for the cheapest flight from Washington, D.C. Dulles Intl Airport to Seattle? While on average our users pay £280, our data indicates the cheapest price to be £98. The most popular route (Washington, D.C. Dulles Intl - Seattle/Tacoma Intl), is priced around £157.

  • 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, February is the cheapest month in which you can book a flight from Washington, D.C. Dulles Intl Airport to Seattle (average of £89). Flying from Washington, D.C. Dulles Intl Airport to Seattle in September is currently the most expensive (average of £174). 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
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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?

Cheapflights simply makes it quick and affordable to book flights from Dulles Intl to Seattle by bringing together all flight options from hundreds of airlines and agencies online — and put it in one place for you to choose from. Plus, Cheapflights is 100% free to use for all.

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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