Find flights
Deals
When to book
FAQs

Cheap flights from Washington, D.C. Dulles Intl Airport to Seattle from £103

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 21/1. Fares are subject to change and may not be available on all flights or dates of travel.
IAD — SEA
10 Sep — 17 Sep1
1 adult

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 5 September 2025.

Round-trip from

£191

One-way from

£103

Popular in

December

Cheapest in

February

Average price

£276
Alaska Airlines
  • Alaska Airlines
  • 18/11-18/11
  • 1 total stop
  • 30h 02m total
  • Washington, D.C. to Seattle
Search Deals
American Airlines
  • American Airlines
  • 6/1
  • 1 total stop
  • 9h 56m total
  • Washington, D.C. to Seattle
Search Deals
Highest demand for flights based on searches. 1% potential increase in price (£3 potential increase over avg. return price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease (£5 potential savings vs. average return price).
Search Deals
Average for round-trip flights in September 2025
Search Deals

Find flight deals from Dulles Intl to Seattle

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 5 September 2025.

Tue 18/1107:43IAD - SEA
Nonstop5h 52mAlaska Airlines
Tue 18/1114:03SEA - IAD
1 stop24h 10mAlaska Airlines
Deal found 4/9£191
Thu 16/1007:35IAD - SEA
Nonstop5h 53mDelta
Mon 20/1016:48SEA - IAD
Nonstop4h 52mDelta
Deal found 5/9£206
Thu 11/1207:35IAD - SEA
Nonstop6h 01mHawaiian Airlines
Tue 16/1208:40SEA - IAD
Nonstop4h 56mHawaiian Airlines
Deal found 4/9£207
Tue 18/1117:55IAD - SEA
Nonstop5h 59mUnited Airlines
Wed 7/105:00SEA - IAD
1 stop8h 35mUnited Airlines
Deal found 4/9£211
Tue 28/1012:09IAD - SEA
1 stop13h 18mDelta
Sun 9/1116:59SEA - IAD
Nonstop4h 55mDelta
Deal found 2/9£212
Wed 1/1017:55IAD - SEA
Nonstop5h 49mUnited Airlines
Tue 14/1013:57SEA - IAD
1 stop7h 24mUnited Airlines
Deal found 5/9£214
Tue 28/1012:09IAD - SEA
1 stop13h 18mDelta
Mon 10/1121:59SEA - IAD
1 stop18h 09mDelta
Deal found 2/9£218
Wed 29/1017:40IAD - SEA
1 stop18h 45mAlaska Airlines
Sun 2/1120:07SEA - IAD
1 stop18h 06mAlaska Airlines
Deal found 4/9£220
Thu 25/907:00IAD - SEA
Nonstop5h 40mAlaska Airlines
Thu 2/1016:20SEA - IAD
Nonstop5h 03mAlaska Airlines
Deal found 4/9£221
Thu 25/917:55IAD - SEA
Nonstop5h 49mUnited Airlines
Sun 28/908:00SEA - IAD
Nonstop5h 09mUnited Airlines
Deal found 4/9£225
Fri 26/915:00IAD - SEA
1 stop9h 02mUnited Airlines
Sun 28/908:00SEA - IAD
Nonstop5h 09mUnited Airlines
Deal found 4/9£226
Fri 31/1019:59IAD - SEA
1 stop17h 19mDelta
Mon 10/1121:59SEA - IAD
1 stop18h 09mDelta
Deal found 2/9£226

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 5 September 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 20/11

07:43-10:35

Nonstop5h 52m

Seattle/Tacoma Intl

Wed 3/12

08:40-16:36

Nonstop4h 56m

£206

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 2/10

07:00-09:40

Nonstop5h 40m

Seattle/Tacoma Intl

Mon 6/10

16:20-00:23

Nonstop5h 03m

£206

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Fri 17/10

17:55-20:44

Nonstop5h 49m

Seattle/Tacoma Intl

Sat 25/10

08:00-16:09

Nonstop5h 09m

£206

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sun 23/11

07:15-10:19

Nonstop6h 04m

Seattle/Tacoma Intl

Fri 5/12

16:30-00:26

Nonstop4h 56m

£206

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 22/10

06:25-09:08

Nonstop5h 43m

Seattle/Tacoma Intl

Sat 25/10

10:14-18:28

Nonstop5h 14m

£206

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 5/11

18:13-21:12

Nonstop5h 59m

Seattle/Tacoma Intl

Mon 10/11

22:29-06:23

Nonstop4h 54m

£206

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 1/10

07:35-10:16

Nonstop5h 41m

Seattle/Tacoma Intl

Wed 8/10

16:48-00:40

Nonstop4h 52m

£206

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Tue 11/11

07:43-10:35

Nonstop5h 52m

Seattle/Tacoma Intl

Sun 16/11

22:29-06:23

Nonstop4h 54m

£206

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Tue 25/11

07:15-10:19

Nonstop6h 04m

Seattle/Tacoma Intl

Thu 4/12

16:30-00:26

Nonstop4h 56m

£206

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 29/10

07:43-10:35

Nonstop5h 52m

Seattle/Tacoma Intl

Wed 5/11

22:29-06:23

Nonstop4h 54m

£206

Flights are sorted by cheapest return flights first.

Deals found on 3/9

Showing 1-10 of 19 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 29 August 2025.

The best time to book flights from Washington, D.C. Dulles Intl Airport to Seattle is 28 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, January is the cheapest month in which you can book a flight from Washington, D.C. Dulles Intl Airport to Seattle (average of £622). Flying from Washington, D.C. Dulles Intl Airport to Seattle in July is currently the most expensive (average of £946). 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 5 September 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 23 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, Hawaiian Airlines, and United Airlines can get you from Washington, D.C. Dulles Intl Airport to Seattle in just under 5h 40m. 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 Japan Airlines (97%), China Eastern (90%) and Delta (90%).

  • 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, January is the cheapest month in which you can book a flight from Washington, D.C. Dulles Intl Airport to Seattle (average of £622). Flying from Washington, D.C. Dulles Intl Airport to Seattle in July is currently the most expensive (average of £946). 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

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.