Find flights
Deals
When to book
FAQs

Cheap flights from Washington, D.C. Dulles Intl Airport to Seattle from £97

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 5/3. Fares are subject to change and may not be available on all flights or dates of travel.
IAD — SEA
11 Jan — 18 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

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 12 December 2025.

Wed 31/1206:20IAD - SEA
1 stop10h 38mUnited Airlines
Sat 10/108:10SEA - IAD
Nonstop5h 06mUnited Airlines
Deal found 10/12£238
Tue 30/1206:30IAD - SEA
1 stop8h 33mUnited Airlines
Wed 7/108:10SEA - IAD
Nonstop5h 06mUnited Airlines
Deal found 9/12£279
Wed 31/1209:47IAD - SEA
1 stop11h 19mUnited Airlines
Wed 7/108:10SEA - IAD
Nonstop5h 06mUnited Airlines
Deal found 11/12£286
Tue 30/1206:30IAD - SEA
1 stop8h 33mUnited Airlines
Tue 6/108:10SEA - IAD
Nonstop5h 06mUnited Airlines
Deal found 9/12£294
Wed 31/1206:20IAD - SEA
1 stop10h 38mUnited Airlines
Sun 4/123:59SEA - IAD
1 stop8h 29mUnited Airlines
Deal found 10/12£316
Fri 26/1207:05IAD - SEA
Nonstop5h 57mDelta
Thu 8/115:20SEA - IAD
Nonstop4h 50mDelta
Deal found 11/12£326
Thu 25/1207:05IAD - SEA
1 stop8h 31mDelta
Sat 10/115:20SEA - IAD
Nonstop4h 50mDelta
Deal found 11/12£334

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 12 December 2025.

Round-trip from

£161

One-way from

£97

Popular in

June

Cheapest in

January

Average price

£335

Good round-trip deal

£1,507 or less
United Airlines
  • United Airlines
  • 9/1-16/1
  • Nonstop
  • 11h 08m total
  • Washington, D.C. to Seattle
Search Deals
Delta
  • Delta
  • 7/1
  • 1 total stop
  • 10h 50m total
  • Washington, D.C. to Seattle
Search Deals
Highest demand for flights based on searches. 7% potential increase in price (£18 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 December 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 12 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

Fri 16/1

17:55-20:57

Nonstop6h 02m

Seattle/Tacoma Intl

Mon 19/1

07:00-17:35

1 stop7h 35m

£170

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 7/1

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Fri 9/1

15:20-23:10

Nonstop4h 50m

£178

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 29/1

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Sun 1/2

15:20-23:10

Nonstop4h 50m

£185

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Fri 16/1

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Tue 20/1

15:20-23:10

Nonstop4h 50m

£185

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Fri 30/1

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Sun 1/2

15:20-23:10

Nonstop4h 50m

£185

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Fri 9/1

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Fri 16/1

15:20-23:10

Nonstop4h 50m

£185

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 5/2

07:00-14:45

1 stop10h 45m

Seattle/Tacoma Intl

Fri 6/2

15:20-23:10

Nonstop4h 50m

£186

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Mon 19/1

17:17-22:43

1 stop8h 26m

Seattle/Tacoma Intl

Wed 21/1

19:30-06:47

1 stop8h 17m

£190

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 5/2

17:26-09:28

1 stop19h 02m

Seattle/Tacoma Intl

Fri 6/2

20:21-17:04

1 stop17h 43m

£191

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 5/3

17:26-22:45

1 stop8h 19m

Seattle/Tacoma Intl

Sun 8/3

19:10-05:17

1 stop7h 07m

£192

Flights are sorted by cheapest return flights first.

Deals found on 10/12

Showing 1-10 of 21 results
1
2
3

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 5 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 March is currently the most expensive (average of £198). 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 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 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 can get you from Washington, D.C. Dulles Intl Airport to Seattle in just under 10h 37m. Your travel time can differ by up to . The distance from Washington, D.C. Dulles Intl Airport to Seattle is about 2299 mi.

  • 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 (89%), Alaska Airlines (81%) and China Eastern (80%).

  • 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 £1,507, our data indicates the cheapest price to be £379. The most popular route (Washington, D.C. Dulles Intl - Seattle/Tacoma Intl), is priced around £207.

  • 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 March is currently the most expensive (average of £198). 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

Travelling to a place near Seattle?

Book flights to Seattle if you plan to visit one of these locations
Tacoma
Leavenworth
SeaTac

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Fly with Cheapflights

Find the best flight deals on Cheapflights, where travellers can enjoy low prices and a wide availability of flights to their desired destinations.

How does Cheapflights help users find flights from Dulles Intl to Seattle?

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.

100% Free

Cheapflights is completely free to use, so you can start saving the moment you arrive.

Book with Flexibility

Our users can plan ahead with confidence and find flights with no change fees

Travel Smart

Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.