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Cheap flights from Washington, D.C. Dulles Intl Airport to Seattle from £149

IAD — SEA
21 Sep — 28 Sep1
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 6/1009:38 -
Nonstop5h 42m
Tue 6/1014:59 -
1 stop23h 51m
Deal found 19/8£254
Thu 15/1007:02 -
Nonstop5h 42m
Tue 20/1015:56 -
Nonstop5h 03m
Deal found 20/8£260
Fri 25/917:57 -
Nonstop5h 47m
Mon 5/1015:56 -
Nonstop5h 03m
Deal found 18/8£276
Fri 18/907:25 -
Nonstop5h 40m
Sat 26/911:45 -
Nonstop5h 16m
Deal found 18/8£278
Fri 25/915:36 -
1 stop9h 23m
Sun 27/923:14 -
Nonstop5h 03m
Deal found 18/8£281
Wed 30/919:47 -
1 stop16h 33m
Sat 3/1008:15 -
Nonstop5h 15m
Deal found 22/8£286
Wed 4/1107:46 -
Nonstop5h 50m
Sun 8/1120:48 -
1 stop17h 52m
Deal found 18/8£287
Tue 29/917:57 -
Nonstop5h 47m
Sun 4/1021:36 -
Nonstop5h 04m
Deal found 20/8£288
Sat 3/1009:38 -
Nonstop5h 42m
Sun 4/1021:08 -
1 stop17h 42m
Deal found 19/8£290
Tue 13/1019:24 -
1 stop17h 04m
Mon 19/1020:07 -
1 stop18h 43m
Deal found 18/8£291
Thu 15/1005:01 -
1 stop7h 57m
Tue 20/1021:42 -
1 stop8h 02m
Deal found 20/8£292

Find flight deals from Dulles Intl to Seattle

Round-trip from

£254

One-way from

£149

Popular in

June

Cheapest in

January

Average price

£324

Good one-way deal

£144 or less
Alaska Airlines
  • Alaska Airlines
  • 6/10-6/10
  • 1 total stop
  • 29h 33m total
  • Washington, D.C. to Seattle
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Alaska Airlines
  • Alaska Airlines
  • 19/10
  • 1 total stop
  • 17h 04m 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 25/9

07:25-10:05

Nonstop5h 40m

Seattle/Tacoma Intl

Mon 28/9

14:52-22:56

Nonstop5h 04m

£276

Washington, D.C.Seattle

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

IADSEA

Washington, D.C. Dulles Intl

Thu 4/2

07:05-10:05

Nonstop6h 00m

Seattle/Tacoma Intl

Sun 7/2

15:55-23:51

Nonstop4h 56m

£276

Washington, D.C.Seattle

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

IADSEA

Washington, D.C. Dulles Intl

Thu 1/10

15:36-21:59

1 stop9h 23m

Seattle/Tacoma Intl

Sun 4/10

08:25-16:31

Nonstop5h 06m

£281

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

Mon 19/10

19:24-09:28

1 stop17h 04m

Seattle/Tacoma Intl

Mon 26/10

21:08-17:50

1 stop17h 42m

£291

Washington, D.C.Seattle

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

IADSEA

Washington, D.C. Dulles Intl

Sun 18/10

17:45-20:37

Nonstop5h 52m

Seattle/Tacoma Intl

Thu 22/10

23:14-07:17

Nonstop5h 03m

£306
Fastest return journey

Washington, D.C.Seattle

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

IADSEA

Washington, D.C. Dulles Intl

Fri 25/9

09:03-11:39

Nonstop5h 36m

Seattle/Tacoma Intl

Sun 27/9

21:35-05:40

Nonstop5h 05m

£306

Washington, D.C.Seattle

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

IADSEA

Washington, D.C. Dulles Intl

Mon 21/9

07:25-10:05

Nonstop5h 40m

Seattle/Tacoma Intl

Wed 23/9

14:52-22:56

Nonstop5h 04m

£306

Washington, D.C.Seattle

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

IADSEA

Washington, D.C. Dulles Intl

Sun 27/9

07:25-10:05

Nonstop5h 40m

Seattle/Tacoma Intl

Wed 30/9

14:52-22:56

Nonstop5h 04m

£306

Flights are sorted by cheapest return flights first.

Deals found on 22/8

Showing 1-10 of 22 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 £169). Flying from Washington, D.C. Dulles Intl Airport to Seattle in June is currently the most expensive (average of £393). 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 £254 on Alaska Airlines (6 Oct–6 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 15 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 52m. Your travel time will be generally consistent. The distance from Washington, D.C. Dulles Intl Airport to Seattle is about 2299 mi. Most flights are nonstop.

  • 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 £276.

  • 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 £169). Flying from Washington, D.C. Dulles Intl Airport to Seattle in June is currently the most expensive (average of £393). 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.

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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