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Cheap flights from Washington, D.C. Dulles Intl Airport to Seattle from £142

IAD — SEA
24 Sep — 1 Oct1
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

Tue 20/1019:24 -
1 stop20h 04m
Wed 21/1015:56 -
Nonstop5h 03m
Deal found 25/8£247
Thu 15/1007:02 -
Nonstop5h 42m
Tue 20/1015:56 -
Nonstop5h 03m
Deal found 20/8£260
Fri 25/917:45 -
Nonstop5h 52m
Sun 4/1008:25 -
Nonstop5h 06m
Deal found 24/8£276
Thu 24/907:25 -
Nonstop5h 40m
Wed 30/914:52 -
Nonstop5h 04m
Deal found 23/8£277
Thu 19/1117:17 -
Nonstop5h 56m
Sun 22/1108:15 -
Nonstop4h 58m
Deal found 23/8£280
Fri 25/915:36 -
1 stop9h 23m
Mon 28/923:14 -
Nonstop5h 03m
Deal found 24/8£281
Fri 25/919:47 -
1 stop16h 33m
Thu 1/1015:56 -
Nonstop5h 03m
Deal found 25/8£284
Fri 25/919:47 -
1 stop16h 33m
Sat 3/1008:15 -
Nonstop5h 15m
Deal found 23/8£285
Wed 30/919:47 -
1 stop16h 33m
Sat 3/1008:15 -
Nonstop5h 15m
Deal found 22/8£286
Thu 5/1117:17 -
Nonstop5h 56m
Sun 8/1119:46 -
1 stop18h 54m
Deal found 23/8£287
Fri 25/919:47 -
1 stop16h 33m
Sun 27/921:35 -
Nonstop5h 05m
Deal found 24/8£287
Tue 29/917:57 -
Nonstop5h 47m
Sun 4/1021:36 -
Nonstop5h 04m
Deal found 20/8£288

Find flight deals from Dulles Intl to Seattle

Round-trip from

£247

One-way from

£142

Popular in

June

Cheapest in

January

Average price

£324

Good one-way deal

£144 or less
Alaska Airlines
  • Alaska Airlines
  • 20/10-21/10
  • 1 total stop
  • 25h 07m total
  • Washington, D.C. to Seattle
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Alaska Airlines
  • Alaska Airlines
  • 1/9
  • 1 total stop
  • 16h 45m total
  • Washington, D.C. to Seattle
Search Deals
Highest demand for flights based on searches. 21% potential increase in price (£56 potential increase over avg. return price).
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Cheapest flight prices on average. 3% potential price decrease (£8 potential savings vs. average return price).
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Average for round-trip flights in August 2026
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Price to beat on a one-way flight from Washington, D.C. Dulles Intl to Seattle/Tacoma Intl.
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Cheapflights Fare Finder

 
Use the filters below to find and compare flights from Washington, D.C. Dulles Intl Airport to Seattle that are best for you.

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Fly to

Route

Depart

Return

Price

Cheapest return flight

Washington, D.C.Seattle

IAD Washington, D.C. Dulles Intl - SEA Seattle/Tacoma Intl

IADSEA

Washington, D.C. Dulles Intl

Fri 23/10

07:05-09:56

Nonstop5h 51m

Seattle/Tacoma Intl

Sun 25/10

14:50-22:49

Nonstop4h 59m

£276
Fastest return journey

Washington, D.C.Seattle

IAD Washington, D.C. Dulles Intl - SEA Seattle/Tacoma Intl

IADSEA

Washington, D.C. Dulles Intl

Thu 1/10

07:25-10:05

Nonstop5h 40m

Seattle/Tacoma Intl

Tue 6/10

14:50-22:49

Nonstop4h 59m

£276

Washington, D.C.Seattle

IAD Washington, D.C. Dulles Intl - SEA Seattle/Tacoma Intl

IADSEA

Washington, D.C. Dulles Intl

Wed 28/10

07:05-09:56

Nonstop5h 51m

Seattle/Tacoma Intl

Sun 1/11

11:58-20:06

Nonstop5h 08m

£276

Washington, D.C.Seattle

IAD Washington, D.C. Dulles Intl - SEA Seattle/Tacoma Intl

IADSEA

Washington, D.C. Dulles Intl

Fri 29/1

15:45-21:56

1 stop9h 11m

Seattle/Tacoma Intl

Sun 31/1

08:00-15:53

Nonstop4h 53m

£281

Washington, D.C.Seattle

IAD Washington, D.C. Dulles Intl - SEA Seattle/Tacoma Intl

IADSEA

Washington, D.C. Dulles Intl

Fri 16/10

15:36-21:59

1 stop9h 23m

Seattle/Tacoma Intl

Wed 28/10

08:09-16:08

Nonstop4h 59m

£281

Washington, D.C.Seattle

IAD Washington, D.C. Dulles Intl - SEA Seattle/Tacoma Intl

IADSEA

Washington, D.C. Dulles Intl

Wed 30/9

19:47-09:20

1 stop16h 33m

Seattle/Tacoma Intl

Tue 6/10

15:56-23:59

Nonstop5h 03m

£284

Washington, D.C.Seattle

IAD Washington, D.C. Dulles Intl - SEA Seattle/Tacoma Intl

IADSEA

Washington, D.C. Dulles Intl

Thu 15/10

09:38-12:20

Nonstop5h 42m

Seattle/Tacoma Intl

Tue 20/10

20:35-17:50

1 stop18h 15m

£284

Washington, D.C.Seattle

IAD Washington, D.C. Dulles Intl - SEA Seattle/Tacoma Intl

IADSEA

Washington, D.C. Dulles Intl

Fri 30/10

17:50-20:56

Nonstop6h 06m

Seattle/Tacoma Intl

Wed 4/11

22:56-11:52

1 stop9h 56m

£284

Washington, D.C.Seattle

IAD Washington, D.C. Dulles Intl - SEA Seattle/Tacoma Intl

IADSEA

Washington, D.C. Dulles Intl

Wed 7/10

07:02-09:44

Nonstop5h 42m

Seattle/Tacoma Intl

Sun 11/10

21:36-05:40

Nonstop5h 04m

£284

Washington, D.C.Seattle

IAD Washington, D.C. Dulles Intl - SEA Seattle/Tacoma Intl

IADSEA

Washington, D.C. Dulles Intl

Tue 13/10

19:24-09:28

1 stop17h 04m

Seattle/Tacoma Intl

Thu 15/10

21:08-17:50

1 stop17h 42m

£291

Flights are sorted by cheapest return flights first.

Deals found on 25/8

Showing 1-10 of 20 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

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 20 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 £165). Flying from Washington, D.C. Dulles Intl Airport to Seattle in June is currently the most expensive (average of £394). 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?

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?

Airfare is typical for this route at the moment.

Washington, D.C. Dulles Intl Airport to Seattle flights typically cost between £241 and £387 in October.
The cheapest return price found within the last 5 days was £247 on Alaska Airlines (20 Oct–21 Oct).

Related info for your journey

  • 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 21 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 and United Airlines can get you from Washington, D.C. Dulles Intl Airport to Seattle in just under 5h 51m. Your travel time can differ by up to 3h 20m. 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 Finnair (96%), Japan Airlines (89%) and United Airlines (82%).

  • 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 £406, our data indicates the cheapest price to be £144. The most popular route (Washington, D.C. Dulles Intl - Seattle/Tacoma Intl), is priced around £495.

  • 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 £165). Flying from Washington, D.C. Dulles Intl Airport to Seattle in June is currently the most expensive (average of £394). 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

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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.

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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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