$121 Cheap Flights from Washington (IAD) to Seattle (SEA)

View $121 flight on Mon, Sep 15, 2025Opens in a new window

Popular airlines from Washington Dulles Intl. Airport (IAD) to Seattle-Tacoma International Airport (SEA)

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Today's featured flight deals from Washington Dulles Intl. Airport (IAD) to Seattle-Tacoma International Airport (SEA)

Nonstop
Carry-on included
Lower price than typical

Cheap Flights from Washington to Seattle (IAD-SEA)

Prices were available within the past 7 days and start at $121 for one-way flights and $259 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Frontier Airlines
Mon, Sep 22 - Wed, Oct 1
IAD
Washington
SEA
Seattle
$259 Roundtrip, found 4 hours ago
$259
Roundtrip
found 4 hours ago
Select Frontier Airlines flight, departing Mon, Sep 22 from Washington to Seattle, returning Wed, Oct 1, priced at $259 found 4 hours ago
Southwest Airlines
Tue, Oct 7 - Thu, Oct 16
IAD
Washington
SEA
Seattle
$260 Roundtrip, found 4 hours ago
$260
Roundtrip
found 4 hours ago
Select Southwest Airlines flight, departing Tue, Oct 7 from Washington to Seattle, returning Thu, Oct 16, priced at $260 found 4 hours ago
Southwest Airlines
Tue, Sep 23 - Fri, Oct 3
IAD
Washington
SEA
Seattle
$265 Roundtrip, found 2 hours ago
$265
Roundtrip
found 2 hours ago
Select Southwest Airlines flight, departing Tue, Sep 23 from Washington to Seattle, returning Fri, Oct 3, priced at $265 found 2 hours ago
Southwest Airlines
Tue, Oct 7 - Fri, Oct 17
IAD
Washington
SEA
Seattle
$265 Roundtrip, found 2 hours ago
$265
Roundtrip
found 2 hours ago
Select Southwest Airlines flight, departing Tue, Oct 7 from Washington to Seattle, returning Fri, Oct 17, priced at $265 found 2 hours ago
Frontier Airlines
Mon, Sep 8 - Wed, Sep 17
IAD
Washington
SEA
Seattle
$269 Roundtrip, found 4 hours ago
$269
Roundtrip
found 4 hours ago
Select Frontier Airlines flight, departing Mon, Sep 8 from Washington to Seattle, returning Wed, Sep 17, priced at $269 found 4 hours ago
Frontier Airlines
Sat, Oct 25 - Tue, Nov 4
IAD
Washington
SEA
Seattle
$270 Roundtrip, found 2 hours ago
$270
Roundtrip
found 2 hours ago
Select Frontier Airlines flight, departing Sat, Oct 25 from Washington to Seattle, returning Tue, Nov 4, priced at $270 found 2 hours ago
Southwest Airlines
Tue, Nov 4 - Thu, Nov 13
IAD
Washington
SEA
Seattle
$275 Roundtrip, found 4 hours ago
$275
Roundtrip
found 4 hours ago
Select Southwest Airlines flight, departing Tue, Nov 4 from Washington to Seattle, returning Thu, Nov 13, priced at $275 found 4 hours ago
Alaska Airlines
Mon, Sep 22 - Mon, Sep 29
IAD
Washington
SEA
Seattle
$277 Roundtrip, just found
$277
Roundtrip
just found
Select Alaska Airlines flight, departing Mon, Sep 22 from Washington to Seattle, returning Mon, Sep 29, priced at $277 just found
Delta
Tue, Oct 14 - Mon, Oct 20
IAD
Washington
SEA
Seattle
$277 Roundtrip, just found
$277
Roundtrip
just found
Select Delta flight, departing Tue, Oct 14 from Washington to Seattle, returning Mon, Oct 20, priced at $277 just found
United
Tue, Oct 14 - Mon, Oct 20
IAD
Washington
SEA
Seattle
$277 Roundtrip, just found
$277
Roundtrip
just found
Select United flight, departing Tue, Oct 14 from Washington to Seattle, returning Mon, Oct 20, priced at $277 just found

Find the cheapest month to fly from Washington (IAD) to Seattle (SEA)

September is typically the cheapest month to fly

From $198 - $312 per traveler.

Graph displaying average flight prices per month

Flights from Washington (IAD) to Seattle (SEA)
Origin airport
Washington Dulles Intl.
Destination airport
Seattle - Tacoma Intl.
Airlines serving
Alaska Airlines, American Airlines, Delta, Frontier Airlines, Hawaiian Airlines, Southwest Airlines, Sun Country Airlines, United
Roundtrip price
$258
Distance
2299 mi
Average flight time
2 hours 43 mins

Washington to Seattle Flights

The cheapest times to fly from Washington to Seattle

On average, Thursday can be the cheapest time to fly, according to data from the Airlines Reporting Corporation (ARC), one of the world's biggest databases for global airline sales. The data reveals that you could save up to 16% by flying on a Thursday—the cheapest day to travel on average—instead of a Sunday—the most expensive. Some of the most affordable flights from Washington to Seattle are during the month of September. You can find some of the cheapest flights from Washington to Seattle with Expedia's search tool and vast selection of airlines.

 

The best time to book a flight from Washington to Seattle

Sunday is one of the best days to book for cheap flights from Washington to Seattle: Tickets reserved on a Sunday cost between 6% and 13% less than those reserved on a Friday, according to ARC data. The data also suggests booking early can also lead to cheaper airfares. You could save 24% by buying your tickets for domestic flights at least a month in advance and 10% by booking international flights 2 months in advance.

 

How to find cheap round-trip tickets from Washington to Seattle

Being flexible with your dates and using Expedia's Price Drop Protection and Price Tracking features are some of the best ways of finding a cheap ticket from Washington to Seattle in 2025. You can also book with separate airlines for your outbound and return journeys, from $121 one-way. Expedia also offers Price Drop Protection, so if the cost of your airfare goes down after booking, you'll receive a credit for the difference*. This is available for a small fee, and is free to One Key Gold and Platinum tier members.

 

Expedia's Price Tracking feature means you can stay on top of airfares without manually checking every day. It sends you automated price alerts for cheap Washington to Seattle flights and uses historical data to indicate when the best time to book is. Download Expedia's free app to activate this handy tool in a few easy taps.

 

You could also save big by booking one of Expedia's vacation packages. Bundling together your Washington to Seattle airfare with your accommodations and car rental is often cheaper than booking everything separately. There’s also One Key, Expedia's generous rewards program. Join for free and you could earn One Key cash on most bookings to save on future adventures.

 

*Terms apply.

 

Disclaimer: ARC The statistics are based on average round-trip ticket prices between January and August 2023. The percentages you see are averages.

 

Frequently asked questions

How much does a flight from Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA) cost?
Secure a cheap one-way flight from $121 or cheap return flight from $259 from Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA) with Expedia. Enter your travel dates and sort by "Price (lowest to highest)" to find our cheapest flight offers on this route.
What is the cheapest month to fly from Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA)?
Traveling in September may help you find better deals, as it's the cheapest month for flights between IAD and SEA. You'll often find the lowest prices during the off-season.
Which airlines fly direct from Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA)?
Fly straight to Seattle - Tacoma Intl. Airport (SEA). 3 airlines offer direct flights from Washington Dulles Intl. Airport (IAD), including:

  • Delta Air Lines
  • United Airlines
  • Alaska Airlines

What is the cheapest airline that flies from Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA)?
The cheapest airline to offer flights between Washington Dulles Intl. Airport (IAD) and Seattle - Tacoma Intl. Airport (SEA) can change depending on your travel plans. Alaska Airlines and Delta Air Lines are just some of the choices offering reasonable prices. Use Expedia's search tool to compare airlines in one place and find the right IAD to SEA flight that fits your budget.
How many flights per day from Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA)?
When departing from Washington Dulles Intl. Airport (IAD), you can pick from an average of 3 daily nonstop flights to Seattle - Tacoma Intl. Airport (SEA).
What are the most popular departure times for flights from Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA)?
More travelers fly between IAD and SEA at 4 PM than at any other point in the day. Rather go when it's quieter? Consider flying outside peak hours and you're likely to save on your fare as well.
What day of the week has the most flights from IAD to SEA?
Friday offers the most flights from Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA). Consider leaving on this day and you'll have the best chance of finding a departure that fits your itinerary.
What is the earliest flight from Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA)?
The first flight of the day out of Washington Dulles Intl. Airport (IAD) is at around 4:05PM UTC-5. Board this plane and you'll reach Seattle - Tacoma Intl. Airport (SEA) at approximately 7:06PM UTC-8. The total time in the air is 6h 1m.
How long does it take to fly from Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA)?
It usually takes 6 hours and 1 minute to travel the 2,300 mi from IAD to SEA.
What airline has the least delays from IAD to SEA?
With 84% of flights generally landing on time, United Airlines has the best on-time performance for direct flights from Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA). To check your flight status and receive notifications if anything changes, head to the Expedia App.
What is the best time to fly from Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA)?
To avoid potential delays on the Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA) route, aim to travel before 3 PM. Flights after this time are 22% more likely to be canceled.**Most reliable time of the day and month to travel recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.
What airports do you fly into for Seattle from Washington Dulles Intl. Airport (IAD)?
Seattle - Tacoma Intl. Airport (SEA) is the only airport in Seattle with direct flights from Washington Dulles Intl. Airport (IAD). Consider the options and find affordable fares on Expedia.
Is it cheaper to buy a plane ticket from Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA) last-minute?
Holding off until right before your break to book your flight from IAD to SEA generally means paying more. While it's possible to find some last-minute discounts, they're not always guaranteed. Keep your travel schedule open for the best chance of landing a bargain.
Is it cheaper to book an IAD to SEA flight and hotel package?
Booking an IAD to SEA flight and hotel package tends to be cheaper than booking separately. With Expedia, you can enjoy the ease of organizing your travels in one place. Pick from our extensive range of accommodations and then add car rentals, activities and flights to your booking. Bundle it all together, and you could save hundreds of dollars.
Can I cancel or change the date of my flight from Washington Dulles Intl. Airport (IAD) to Seattle - Tacoma Intl. Airport (SEA)?
In most instances, you can cancel or reschedule your IAD to SEA flight. However, additional charges may apply, especially if your booking was made over 24 hours ago. Double-check your itinerary for the airline's guidelines and fees on flight changes, or if you need further details, visit our Customer Service portal.

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*Available to One Key members.