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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 14/11. Fares are subject to change and may not be available on all flights or dates of travel.
IAD — SEA
12 Oct — 19 Oct1
1 adult
1 adult, Economy

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 12 September 2025.

Round-trip from

£175

One-way from

£97

Popular in

December

Cheapest in

February

Average price

£274
Southwest
  • Southwest
  • 3/11-11/11
  • 2 total stops
  • 21h 40m total
  • Washington, D.C. to Seattle
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Southwest
  • Southwest
  • 14/11
  • 1 total stop
  • 7h 45m total
  • Washington, D.C. to Seattle
Search Deals
Highest demand for flights based on searches. 0% potential increase in price (£2 potential increase over avg. return price).
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Cheapest flight prices on average. 2% potential price decrease (£5 potential savings vs. average return price).
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Average for round-trip flights in September 2025
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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 12 September 2025.

Mon 3/1117:45IAD - SEA
1 stop8h 10mSouthwest
Tue 11/1105:40SEA - IAD
1 stop13h 30mSouthwest
Deal found 10/9£175
Tue 11/1117:45IAD - SEA
1 stop8h 10mSouthwest
Sat 15/1110:15SEA - IAD
1 stop9h 00mSouthwest
Deal found 10/9£177
Tue 4/1107:40IAD - SEA
2 stops18h 15mSouthwest
Sat 8/1110:15SEA - IAD
1 stop9h 00mSouthwest
Deal found 11/9£178
Sat 1/1117:00IAD - SEA
1 stop8h 30mSouthwest
Tue 4/1105:40SEA - IAD
1 stop7h 05mSouthwest
Deal found 10/9£180
Thu 23/1007:25IAD - SEA
1 stop13h 35mSouthwest
Tue 28/1005:50SEA - IAD
1 stop7h 10mSouthwest
Deal found 11/9£182
Wed 10/1207:40IAD - SEA
1 stop14h 00mSouthwest
Mon 15/1205:40SEA - IAD
1 stop7h 05mSouthwest
Deal found 10/9£189
Thu 16/1006:25IAD - SEA
Nonstop5h 43mAlaska Airlines
Mon 20/1023:25SEA - IAD
Nonstop5h 08mAlaska Airlines
Deal found 12/9£190
Wed 29/1018:40IAD - SEA
1 stop8h 05mSouthwest
Mon 3/1106:15SEA - IAD
2 stops12h 55mSouthwest
Deal found 9/9£192
Wed 12/1107:40IAD - SEA
2 stops17h 50mSouthwest
Sat 15/1110:15SEA - IAD
1 stop9h 00mSouthwest
Deal found 12/9£193
Wed 1/1016:55IAD - SEA
1 stop10h 10mSouthwest
Tue 14/1007:10SEA - IAD
1 stop7h 45mSouthwest
Deal found 10/9£194
Wed 29/1018:40IAD - SEA
1 stop8h 05mSouthwest
Sun 2/1105:15SEA - IAD
1 stop8h 55mSouthwest
Deal found 10/9£196
Fri 3/1017:55IAD - SEA
Nonstop5h 49mUnited Airlines
Tue 7/1007:01SEA - IAD
1 stop9h 02mUnited Airlines
Deal found 11/9£197

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 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

Fri 5/12

07:35-10:36

Nonstop6h 01m

Seattle/Tacoma Intl

Tue 30/12

22:14-06:13

Nonstop4h 59m

£190

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 4/10

07:35-10:16

Nonstop5h 41m

Seattle/Tacoma Intl

Sat 11/10

16:48-00:40

Nonstop4h 52m

£190

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sun 2/11

07:35-10:28

Nonstop5h 53m

Seattle/Tacoma Intl

Tue 25/11

16:59-00:54

Nonstop4h 55m

£190

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 8/10

07:35-10:28

Nonstop5h 53m

Seattle/Tacoma Intl

Tue 14/10

16:48-00:40

Nonstop4h 52m

£190

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 1/11

08:30-16:15

1 stop10h 45m

Seattle/Tacoma Intl

Tue 4/11

08:00-16:07

Nonstop5h 07m

£197

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Fri 3/10

17:55-20:44

Nonstop5h 49m

Seattle/Tacoma Intl

Sat 11/10

10:25-22:06

1 stop8h 41m

£197

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Fri 3/10

12:46-17:53

1 stop8h 07m

Seattle/Tacoma Intl

Mon 6/10

08:00-16:09

Nonstop5h 09m

£197

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Tue 9/12

07:35-10:36

Nonstop6h 01m

Seattle/Tacoma Intl

Tue 16/12

08:40-16:36

Nonstop4h 56m

£205

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 31/12

07:33-10:20

Nonstop5h 47m

Seattle/Tacoma Intl

Sun 4/1

22:14-06:13

Nonstop4h 59m

£205

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 27/11

06:30-11:30

1 stop8h 00m

Seattle/Tacoma Intl

Tue 2/12

23:59-11:23

1 stop8h 24m

£205

Flights are sorted by cheapest return flights first.

Deals found on 11/9

Showing 1-10 of 24 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 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 12 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?

    Delta can get you from Washington, D.C. Dulles Intl Airport to Seattle in just under 6h 04m. 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
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Bothell
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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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