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Cheap flights from Washington, D.C. Dulles Intl Airport to Seattle from £106

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 27/11. Fares are subject to change and may not be available on all flights or dates of travel.
IAD — SEA
7 Dec — 14 Dec1
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 February or January, booked 36 days in advance, depart on a Tuesday or Monday and return on a Monday

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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 7 November 2025.

Wed 3/1207:34IAD - SEA
Nonstop6h 01mAlaska Airlines
Thu 11/1222:11SEA - IAD
Nonstop4h 55mAlaska Airlines
Deal found 7/11£182
Thu 4/1217:55IAD - SEA
Nonstop5h 59mUnited Airlines
Fri 5/1208:10SEA - IAD
Nonstop5h 08mUnited Airlines
Deal found 6/11£183
Wed 3/1207:15IAD - SEA
Nonstop5h 57mDelta
Sun 7/1215:30SEA - IAD
Nonstop4h 57mDelta
Deal found 5/11£186
Thu 27/1117:55IAD - SEA
Nonstop5h 59mUnited Airlines
Sun 7/1223:59SEA - IAD
1 stop8h 24mUnited Airlines
Deal found 4/11£189
Fri 5/1217:37IAD - SEA
1 stop9h 35mAlaska Airlines
Mon 8/1222:11SEA - IAD
Nonstop4h 55mAlaska Airlines
Deal found 6/11£189
Mon 8/1217:55IAD - SEA
Nonstop5h 59mUnited Airlines
Thu 11/1205:00SEA - IAD
1 stop7h 01mUnited Airlines
Deal found 4/11£190
Thu 18/1217:20IAD - SEA
1 stop8h 39mUnited Airlines
Mon 12/108:10SEA - IAD
Nonstop5h 06mUnited Airlines
Deal found 7/11£191
Wed 3/1207:15IAD - SEA
Nonstop5h 57mDelta
Wed 17/1221:59SEA - IAD
1 stop10h 40mDelta
Deal found 5/11£193
Wed 3/1206:00IAD - SEA
1 stop8h 16mUnited Airlines
Wed 3/1219:34SEA - IAD
1 stop8h 56mUnited Airlines
Deal found 5/11£194
Sun 7/1217:55IAD - SEA
Nonstop5h 59mUnited Airlines
Sun 14/1208:10SEA - IAD
Nonstop5h 08mUnited Airlines
Deal found 7/11£195
Wed 3/1206:00IAD - SEA
1 stop9h 42mUnited Airlines
Wed 10/1212:35SEA - IAD
1 stop7h 40mUnited Airlines
Deal found 5/11£196

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 7 November 2025.

Round-trip from

£182

One-way from

£106

Popular in

December

Cheapest in

February

Average price

£296

Good round-trip deal

£1,541 or less
Alaska Airlines
  • Alaska Airlines
  • 30/1-6/2
  • Nonstop
  • 11h 00m total
  • Washington, D.C. to Seattle
Search Deals
United Airlines
  • United Airlines
  • 27/11
  • Nonstop
  • 5h 59m total
  • Washington, D.C. to Seattle
Search Deals
High demand for flights, 0% potential price rise
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 7 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

Tue 9/12

17:37-00:12

1 stop9h 35m

Seattle/Tacoma Intl

Sat 13/12

08:40-16:36

Nonstop4h 56m

£189

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Fri 5/12

17:37-00:12

1 stop9h 35m

Seattle/Tacoma Intl

Sun 14/12

22:11-06:06

Nonstop4h 55m

£189

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Fri 5/12

17:37-00:12

1 stop9h 35m

Seattle/Tacoma Intl

Mon 8/12

22:11-06:06

Nonstop4h 55m

£189

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 4/12

17:37-00:12

1 stop9h 35m

Seattle/Tacoma Intl

Tue 9/12

08:40-16:36

Nonstop4h 56m

£189

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 4/12

17:37-00:12

1 stop9h 35m

Seattle/Tacoma Intl

Sun 7/12

22:11-06:06

Nonstop4h 55m

£189

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 4/12

17:37-00:12

1 stop9h 35m

Seattle/Tacoma Intl

Sat 13/12

08:40-16:36

Nonstop4h 56m

£189

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

Sun 11/1

15:20-23:10

Nonstop4h 50m

£190

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 3/12

07:15-10:12

Nonstop5h 57m

Seattle/Tacoma Intl

Sat 13/12

23:55-11:18

1 stop8h 23m

£193

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 3/12

07:15-10:12

Nonstop5h 57m

Seattle/Tacoma Intl

Thu 11/12

23:15-10:26

1 stop8h 11m

£193

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Mon 5/1

18:29-09:34

1 stop18h 05m

Seattle/Tacoma Intl

Thu 8/1

20:21-17:04

1 stop17h 43m

£196

Flights are sorted by cheapest return flights first.

Deals found on 5/11

Showing 1-10 of 20 results
1
2

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 31 October 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 £121). Flying from Washington, D.C. Dulles Intl Airport to Seattle in March is currently the most expensive (average of £186). 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 7 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 17 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, United Airlines, and Alaska 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 3h 02m. 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 cheapest airlines to fly from Washington, D.C. Dulles Intl Airport to Seattle one-way?

    The cheapest airline one-way is Delta, with whom users have recently found tickets for as low as £111. However, be on the lookout for offers from Southwest and Alaska Airlines, as they are both options that can get you from Washington, D.C. Dulles Intl Airport to Seattle for a low price.

  • 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 Japan Airlines (95%), ITA Airways (91%) and United Airlines (91%).

  • 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 £1,541, our data indicates the cheapest price to be £387. The most popular route (Washington, D.C. Dulles Intl - Seattle/Tacoma Intl), is priced around £204.

  • 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 £121). Flying from Washington, D.C. Dulles Intl Airport to Seattle in March is currently the most expensive (average of £186). 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
Bothell
SeaTac

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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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