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Cheap flights from Washington, D.C. Dulles Intl Airport to Seattle from £102

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 23/2. Fares are subject to change and may not be available on all flights or dates of travel.
IAD — SEA
27 Dec — 3 Jan1
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

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 27 November 2025.

Wed 17/1207:15IAD - SEA
Nonstop5h 57mDelta
Sat 10/115:20SEA - IAD
Nonstop4h 50mDelta
Deal found 27/11£184
Wed 17/1207:34IAD - SEA
Nonstop6h 01mAlaska Airlines
Sat 24/108:30SEA - IAD
Nonstop4h 56mAlaska Airlines
Deal found 24/11£214
Tue 16/1217:55IAD - SEA
Nonstop5h 59mUnited Airlines
Thu 25/1223:15SEA - IAD
Nonstop4h 56mUnited Airlines
Deal found 25/11£226
Tue 16/1207:15IAD - SEA
Nonstop5h 57mDelta
Thu 25/1213:35SEA - IAD
1 stop6h 43mDelta
Deal found 25/11£234
Tue 16/1217:37IAD - SEA
1 stop9h 35mAlaska Airlines
Wed 24/1222:14SEA - IAD
Nonstop4h 59mAlaska Airlines
Deal found 25/11£237
Wed 17/1207:34IAD - SEA
Nonstop6h 01mAlaska Airlines
Wed 24/1222:14SEA - IAD
Nonstop4h 59mAlaska Airlines
Deal found 25/11£244
Wed 17/1206:30IAD - SEA
1 stop11h 59mUnited Airlines
Wed 31/1223:15SEA - IAD
Nonstop4h 56mUnited Airlines
Deal found 25/11£248
Wed 17/1206:30IAD - SEA
1 stop11h 59mUnited Airlines
Thu 1/123:15SEA - IAD
Nonstop4h 56mUnited Airlines
Deal found 25/11£249
Wed 24/1213:00IAD - SEA
1 stop8h 46mUnited Airlines
Sun 18/108:10SEA - IAD
Nonstop5h 06mUnited Airlines
Deal found 26/11£260

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 27 November 2025.

Round-trip from

£184

One-way from

£102

Popular in

December

Cheapest in

January

Average price

£339

Good round-trip deal

£1,529 or less
Delta
  • Delta
  • 5/1-15/1
  • Nonstop
  • 10h 49m total
  • Washington, D.C. to Seattle
Search Deals
Alaska Airlines
  • Alaska Airlines
  • 23/2
  • 1 total stop
  • 18h 08m total
  • Washington, D.C. to Seattle
Search Deals
Highest demand for flights based on searches. 3% potential increase in price (£7 potential increase over avg. return price).
Search Deals
Cheapest flight prices on average. 1% potential price decrease (£4 potential savings vs. average return price).
Search Deals
Average for round-trip flights in November 2025
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 27 November 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

Thu 5/3

18:20-09:28

1 stop18h 08m

Seattle/Tacoma Intl

Tue 10/3

09:27-17:20

Nonstop4h 53m

£188

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 5/3

16:10-23:28

1 stop10h 18m

Seattle/Tacoma Intl

Tue 10/3

08:59-18:47

1 stop6h 48m

£195

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 14/1

12:23-20:00

1 stop10h 37m

Seattle/Tacoma Intl

Tue 20/1

23:10-11:52

1 stop9h 42m

£196

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sun 11/1

14:24-21:15

1 stop9h 51m

Seattle/Tacoma Intl

Wed 14/1

17:12-05:24

1 stop9h 12m

£196

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 17/1

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Sat 17/1

16:05-14:45

1 stop19h 40m

£206

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 12/2

17:17-22:43

1 stop8h 26m

Seattle/Tacoma Intl

Sun 15/2

12:12-23:21

1 stop8h 09m

£208

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 12/2

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Sun 15/2

15:20-23:10

Nonstop4h 50m

£218

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Mon 9/3

07:20-14:45

1 stop10h 25m

Seattle/Tacoma Intl

Mon 9/3

22:59-12:39

1 stop10h 40m

£226

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 8/1

12:23-20:00

1 stop10h 37m

Seattle/Tacoma Intl

Mon 12/1

23:10-11:49

1 stop9h 39m

£233

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 5/3

13:15-19:03

1 stop8h 48m

Seattle/Tacoma Intl

Sat 14/3

08:00-16:02

Nonstop5h 02m

£236

Flights are sorted by cheapest return flights first.

Deals found on 26/11

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 21 November 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 £120). Flying from Washington, D.C. Dulles Intl Airport to Seattle in July is currently the most expensive (average of £181). 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 27 November 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 18 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 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 ITA Airways (91%), United Airlines (90%) and China Eastern (85%).

  • 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 £1,529, our data indicates the cheapest price to be £384. The most popular route (Washington, D.C. Dulles Intl - Seattle/Tacoma Intl), is priced around £151.

  • 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 £120). Flying from Washington, D.C. Dulles Intl Airport to Seattle in July is currently the most expensive (average of £181). 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?

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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