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Cheap flights from Washington, D.C. Dulles Intl Airport to Seattle from £89

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 11/2. Fares are subject to change and may not be available on all flights or dates of travel.
IAD — SEA
11 Feb — 18 Feb1
1 adult
1 adult, Economy, 0 bags
Cheapflights Tip: The best prices from Washington, D.C. Dulles Intl to Seattle/Tacoma Intl are usually found in January or February, booked 36 days in advance, depart on a Tuesday or Monday and return on a Monday

Cheap 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 12 January 2026.

Round-trip from

£148

One-way from

£89

Popular in

June

Cheapest in

January

Average price

£184

Good round-trip deal

£1,500 or less
Delta
  • Delta
  • 18/2-21/2
  • Nonstop
  • 10h 53m total
  • Washington, D.C. to Seattle
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Alaska Airlines
  • Alaska Airlines
  • 19/3
  • Nonstop
  • 5h 53m total
  • Washington, D.C. to Seattle
Search Deals
Highest demand for flights based on searches. 10% potential increase in price (£24 potential increase over avg. return price).
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Cheapest flight prices on average. 1% potential price decrease (£4 potential savings vs. average return price).
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Average for round-trip flights in January 2026
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Price to beat on a round-trip flight from Washington, D.C. Dulles Intl to Seattle/Tacoma Intl.
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Find 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 12 January 2026.

Sat 14/207:05
IAD
-
SEA
Nonstop6h 00m
Alaska Airlines
Thu 19/209:27
SEA
-
IAD
Nonstop4h 53m
Alaska Airlines
Deal found 12/1£148
Sat 14/207:05
IAD
-
SEA
Nonstop6h 00m
Alaska Airlines
Sun 22/221:45
SEA
-
IAD
Nonstop4h 55m
Alaska Airlines
Deal found 12/1£155
Wed 25/211:30
IAD
-
SEA
1 stop9h 59m
American Airlines
Wed 4/322:08
SEA
-
IAD
1 stop7h 40m
American Airlines
Deal found 11/1£162
Wed 4/207:30
IAD
-
SEA
Nonstop5h 59m
Delta
Mon 9/215:20
SEA
-
IAD
Nonstop4h 50m
Delta
Deal found 12/1£163
Sat 7/207:30
IAD
-
SEA
Nonstop5h 59m
Delta
Sun 15/215:20
SEA
-
IAD
Nonstop4h 50m
Delta
Deal found 12/1£164
Tue 24/215:58
IAD
-
SEA
1 stop8h 14m
United Airlines
Mon 2/312:43
SEA
-
IAD
1 stop7h 38m
United Airlines
Deal found 12/1£167
Tue 10/218:04
IAD
-
SEA
Nonstop6h 04m
Alaska Airlines
Tue 17/209:27
SEA
-
IAD
Nonstop4h 53m
Alaska Airlines
Deal found 11/1£169
Fri 13/316:10
IAD
-
SEA
1 stop10h 18m
United Airlines
Tue 17/308:00
SEA
-
IAD
Nonstop5h 02m
United Airlines
Deal found 12/1£170
Sat 14/217:17
IAD
-
SEA
1 stop8h 26m
United Airlines
Sun 15/212:12
SEA
-
IAD
1 stop8h 09m
United Airlines
Deal found 12/1£175
Fri 24/407:10
IAD
-
SEA
Nonstop5h 48m
Alaska Airlines
Wed 29/415:55
SEA
-
IAD
Nonstop5h 14m
Alaska Airlines
Deal found 12/1£176
Fri 13/218:27
IAD
-
SEA
Nonstop6h 08m
Alaska Airlines
Sun 15/221:45
SEA
-
IAD
Nonstop4h 55m
Alaska Airlines
Deal found 12/1£177
Thu 12/206:00
IAD
-
SEA
1 stop7h 42m
Delta
Sun 15/215:20
SEA
-
IAD
Nonstop4h 50m
Delta
Deal found 12/1£178

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 12 January 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

Dulles Intl

Fly to

Seattle

Route

Depart

Return

Price

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 18/2

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Sat 21/2

15:40-23:34

Nonstop4h 54m

£148

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 4/2

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Mon 9/2

07:10-19:09

1 stop8h 59m

£163

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 12/2

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Thu 19/2

15:20-23:10

Nonstop4h 50m

£163

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 21/2

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Wed 25/2

13:30-23:09

1 stop6h 39m

£163

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 14/2

13:20-19:03

1 stop8h 43m

Seattle/Tacoma Intl

Tue 17/2

12:43-23:21

1 stop7h 38m

£175

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Tue 28/4

07:10-09:58

Nonstop5h 48m

Seattle/Tacoma Intl

Tue 5/5

15:55-00:09

Nonstop5h 14m

£176

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Fri 24/4

07:10-09:58

Nonstop5h 48m

Seattle/Tacoma Intl

Wed 29/4

21:41-05:50

Nonstop5h 09m

£176

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 4/3

17:55-20:56

Nonstop6h 01m

Seattle/Tacoma Intl

Wed 18/3

08:00-16:02

Nonstop5h 02m

£176

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 25/4

07:00-09:54

Nonstop5h 54m

Seattle/Tacoma Intl

Wed 29/4

15:55-23:51

Nonstop4h 56m

£176

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Tue 3/3

07:05-10:05

Nonstop6h 00m

Seattle/Tacoma Intl

Thu 5/3

09:27-17:20

Nonstop4h 53m

£178

Flights are sorted by cheapest return flights first.

Deals found on 11/1

Showing 1-10 of 23 results
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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 9 January 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, April is the cheapest month in which you can book a flight from Washington, D.C. Dulles Intl Airport to Seattle (average of £115). Flying from Washington, D.C. Dulles Intl Airport to Seattle in July is currently the most expensive (average of £178). 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 12 January 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 16 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 59m. Your travel time can differ by up to 5h 55m. 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 United Airlines (82%), Austrian Airlines (78%) and Copa Airlines (78%).

  • 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 £1,500, our data indicates the cheapest price to be £377. The most popular route (Washington, D.C. Dulles Intl - Seattle/Tacoma Intl), is priced around £148.

  • 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, April is the cheapest month in which you can book a flight from Washington, D.C. Dulles Intl Airport to Seattle (average of £115). Flying from Washington, D.C. Dulles Intl Airport to Seattle in July is currently the most expensive (average of £178). 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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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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