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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 27/1. Fares are subject to change and may not be available on all flights or dates of travel.
IAD — SEA
27 Jan — 3 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

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 28 December 2025.

Fri 26/1218:43IAD - SEA
Nonstop5h 49mAlaska Airlines
Fri 4/921:03SEA - IAD
1 stop18h 58mAlaska Airlines
Deal found 25/12£487
Fri 26/1207:05IAD - SEA
Nonstop5h 57mDelta
Fri 4/915:55SEA - IAD
Nonstop5h 00mDelta
Deal found 25/12£498
Fri 26/1206:20IAD - SEA
1 stop10h 38mUnited Airlines
Fri 4/911:00SEA - IAD
1 stop11h 17mUnited Airlines
Deal found 25/12£517
Wed 31/1217:55IAD - SEA
Nonstop6h 02mUnited Airlines
Thu 1/107:00SEA - IAD
1 stop11h 21mUnited Airlines
Deal found 25/12£547
Sat 27/1217:55IAD - SEA
Nonstop6h 02mUnited Airlines
Thu 1/107:00SEA - IAD
1 stop11h 21mUnited Airlines
Deal found 25/12£562
Fri 26/1213:45IAD - SEA
2 stops14h 10mSouthwest
Fri 4/906:15SEA - IAD
1 stop8h 00mSouthwest
Deal found 25/12£587
Sun 28/1208:45IAD - SEA
2 stops15h 32mUnited Airlines
Thu 1/107:00SEA - IAD
1 stop11h 21mUnited Airlines
Deal found 25/12£588

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 28 December 2025.

Round-trip from

£147

One-way from

£89

Popular in

December

Cheapest in

January

Average price

£350

Good round-trip deal

£1,494 or less
Delta
  • Delta
  • 21/1-24/1
  • Nonstop
  • 10h 49m total
  • Washington, D.C. to Seattle
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Delta
  • Delta
  • 27/1
  • Nonstop
  • 5h 59m total
  • Washington, D.C. to Seattle
Search Deals
High demand for flights, 4% potential price rise
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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 December 2025
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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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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 28 December 2025.
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

Sat 24/1

18:04-21:08

Nonstop6h 04m

Seattle/Tacoma Intl

Wed 28/1

08:30-16:26

Nonstop4h 56m

£147

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 28/1

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Mon 2/2

15:20-23:10

Nonstop4h 50m

£147

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Tue 24/2

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Sat 7/3

15:20-23:10

Nonstop4h 50m

£147

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 24/1

18:04-21:08

Nonstop6h 04m

Seattle/Tacoma Intl

Fri 30/1

08:30-16:26

Nonstop4h 56m

£147

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 29/1

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Mon 2/2

15:20-23:10

Nonstop4h 50m

£147

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 28/2

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Fri 6/3

15:20-23:10

Nonstop4h 50m

£147

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 26/2

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Sat 7/3

15:20-23:10

Nonstop4h 50m

£147

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 31/1

17:27-21:49

1 stop7h 22m

Seattle/Tacoma Intl

Sat 21/2

15:40-23:34

Nonstop4h 54m

£155

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sun 15/2

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Sat 21/2

06:00-16:28

1 stop7h 28m

£155

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 25/2

17:13-22:05

1 stop7h 52m

Seattle/Tacoma Intl

Fri 6/3

15:20-23:10

Nonstop4h 50m

£155

Flights are sorted by cheapest return flights first.

Deals found on 26/12

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 26 December 2025.

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 £117). Flying from Washington, D.C. Dulles Intl Airport to Seattle in July is currently the most expensive (average of £177). 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 28 December 2025.

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 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?

    Alaska Airlines, 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 2h 27m. 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 ITA Airways (100%), United Airlines (87%) and Austrian 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 £1,494, our data indicates the cheapest price to be £375. The most popular route (Washington, D.C. Dulles Intl - Seattle/Tacoma Intl), is priced around £140.

  • 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 £117). Flying from Washington, D.C. Dulles Intl Airport to Seattle in July is currently the most expensive (average of £177). 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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