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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 12/3. Fares are subject to change and may not be available on all flights or dates of travel.
IAD — SEA
14 Dec — 21 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 14 November 2025.

Fri 5/1207:34IAD - SEA
Nonstop6h 01mAlaska Airlines
Mon 15/1222:11SEA - IAD
Nonstop4h 55mAlaska Airlines
Deal found 13/11£181
Mon 8/1207:34IAD - SEA
Nonstop6h 01mAlaska Airlines
Fri 12/1222:11SEA - IAD
Nonstop4h 55mAlaska Airlines
Deal found 13/11£182
Fri 12/1217:55IAD - SEA
Nonstop5h 59mUnited Airlines
Sat 13/1208:10SEA - IAD
Nonstop5h 08mUnited Airlines
Deal found 12/11£182
Wed 3/1207:15IAD - SEA
Nonstop5h 57mDelta
Sat 6/1215:30SEA - IAD
Nonstop4h 57mDelta
Deal found 11/11£185
Thu 11/1217:55IAD - SEA
Nonstop5h 59mUnited Airlines
Mon 15/1213:05SEA - IAD
1 stop8h 51mUnited Airlines
Deal found 12/11£188
Thu 4/1217:37IAD - SEA
1 stop9h 35mAlaska Airlines
Tue 9/1208:40SEA - IAD
Nonstop4h 56mAlaska Airlines
Deal found 13/11£188
Mon 8/1217:55IAD - SEA
Nonstop5h 59mUnited Airlines
Wed 10/1217:11SEA - IAD
1 stop9h 16mUnited Airlines
Deal found 12/11£189
Wed 3/1207:15IAD - SEA
Nonstop5h 57mDelta
Tue 9/1213:40SEA - IAD
1 stop6h 49mDelta
Deal found 11/11£192
Mon 8/1218:39IAD - SEA
1 stop9h 11mUnited Airlines
Tue 9/1212:35SEA - IAD
1 stop7h 40mUnited Airlines
Deal found 13/11£193
Wed 17/1217:15IAD - SEA
1 stop8h 13mUnited Airlines
Sat 24/108:40SEA - IAD
1 stop9h 27mUnited Airlines
Deal found 13/11£195
Wed 3/1217:37IAD - SEA
1 stop9h 35mAlaska Airlines
Mon 8/1222:11SEA - IAD
Nonstop4h 55mAlaska Airlines
Deal found 12/11£196
Sun 7/1206:03IAD - SEA
1 stop7h 51mDelta
Wed 10/1211:15SEA - IAD
1 stop9h 14mDelta
Deal found 12/11£197

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 14 November 2025.

Round-trip from

£181

One-way from

£106

Popular in

December

Cheapest in

February

Average price

£324

Good round-trip deal

£1,533 or less
Alaska Airlines
  • Alaska Airlines
  • 5/12-7/12
  • Nonstop
  • 10h 56m total
  • Washington, D.C. to Seattle
Search Deals
United Airlines
  • United Airlines
  • 12/3
  • Nonstop
  • 6h 00m total
  • Washington, D.C. to Seattle
Search Deals
Highest demand for flights based on searches. 2% potential increase in price (£7 potential increase over avg. return price).
Search Deals
Cheapest flight prices on average. 1% potential price decrease (£5 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 14 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

Sun 8/2

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Wed 11/2

15:20-23:10

Nonstop4h 50m

£182

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sun 25/1

07:30-10:29

Nonstop5h 59m

Seattle/Tacoma Intl

Thu 29/1

15:20-23:10

Nonstop4h 50m

£182

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 28/1

07:15-14:18

1 stop10h 03m

Seattle/Tacoma Intl

Sun 1/2

06:05-16:46

1 stop7h 41m

£182

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Fri 27/2

07:05-10:05

Nonstop6h 00m

Seattle/Tacoma Intl

Mon 2/3

20:11-17:27

1 stop18h 16m

£188

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sun 11/1

16:11-21:15

1 stop8h 04m

Seattle/Tacoma Intl

Thu 15/1

05:00-16:35

1 stop8h 35m

£197

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Fri 12/12

17:55-20:54

Nonstop5h 59m

Seattle/Tacoma Intl

Fri 19/12

23:39-07:35

Nonstop4h 56m

£200

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 4/12

17:55-20:54

Nonstop5h 59m

Seattle/Tacoma Intl

Sun 7/12

08:10-16:18

Nonstop5h 08m

£201

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Fri 5/12

07:15-10:12

Nonstop5h 57m

Seattle/Tacoma Intl

Sun 7/12

15:30-23:27

Nonstop4h 57m

£211

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 21/2

07:00-14:52

1 stop10h 52m

Seattle/Tacoma Intl

Wed 25/2

15:20-23:10

Nonstop4h 50m

£219

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Thu 4/12

14:30-21:46

1 stop10h 16m

Seattle/Tacoma Intl

Fri 19/12

23:39-07:35

Nonstop4h 56m

£222

Flights are sorted by cheapest return flights first.

Deals found on 13/11

Showing 1-10 of 21 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 7 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 £119). Flying from Washington, D.C. Dulles Intl Airport to Seattle in July is currently the most expensive (average of £182). 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 14 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 19 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 and Alaska 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 cheapest airlines to fly from Washington, D.C. Dulles Intl Airport to Seattle one-way?

    The cheapest airline one-way is United Airlines, with whom users have recently found tickets for as low as £109. However, be on the lookout for offers from Alaska Airlines and Southwest, 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 £1,533, our data indicates the cheapest price to be £385. The most popular route (Washington, D.C. Dulles Intl - Seattle/Tacoma Intl), is priced around £267.

  • 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 £119). Flying from Washington, D.C. Dulles Intl Airport to Seattle in July is currently the most expensive (average of £182). 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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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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