$913 Cheap Flights from Washington (IAD) to Sihanoukville (KOS)

View $913 flight on Mon, Dec 29, 2025Opens in a new window

Popular airlines from Washington Dulles Intl. Airport (IAD) to Sihanoukville (KOS)

Cheap Flights from Washington to Sihanoukville (IAD-KOS)

Prices were available within the past 7 days and start at $913 for one-way flights and $1,168 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Qatar Airways
Thu, Jan 8 - Thu, Jan 22
IAD
Washington
KOS
Sihanoukville
$1,168 Roundtrip, found 23 hours ago
$1,168
Roundtrip
found 23 hours ago
Select Qatar Airways flight, departing Thu, Jan 8 from Washington to Sihanoukville, returning Thu, Jan 22, priced at $1,168 found 23 hours ago
Qatar Airways
Mon, Jan 26 - Thu, Feb 12
IAD
Washington
KOS
Sihanoukville
$1,171 Roundtrip, found 23 hours ago
$1,171
Roundtrip
found 23 hours ago
Select Qatar Airways flight, departing Mon, Jan 26 from Washington to Sihanoukville, returning Thu, Feb 12, priced at $1,171 found 23 hours ago
Qatar Airways
Fri, Jan 9 - Thu, Jan 22
IAD
Washington
KOS
Sihanoukville
$1,208 Roundtrip, found 23 hours ago
$1,208
Roundtrip
found 23 hours ago
Select Qatar Airways flight, departing Fri, Jan 9 from Washington to Sihanoukville, returning Thu, Jan 22, priced at $1,208 found 23 hours ago
Qatar Airways
Fri, Jan 30 - Thu, Feb 12
IAD
Washington
KOS
Sihanoukville
$1,211 Roundtrip, found 23 hours ago
$1,211
Roundtrip
found 23 hours ago
Select Qatar Airways flight, departing Fri, Jan 30 from Washington to Sihanoukville, returning Thu, Feb 12, priced at $1,211 found 23 hours ago
Qatar Airways
Thu, Jan 8 - Wed, Jan 21
IAD
Washington
KOS
Sihanoukville
$1,238 Roundtrip, found 23 hours ago
$1,238
Roundtrip
found 23 hours ago
Select Qatar Airways flight, departing Thu, Jan 8 from Washington to Sihanoukville, returning Wed, Jan 21, priced at $1,238 found 23 hours ago
Qatar Airways
Fri, Jan 9 - Sun, Jan 25
IAD
Washington
KOS
Sihanoukville
$1,248 Roundtrip, found 23 hours ago
$1,248
Roundtrip
found 23 hours ago
Select Qatar Airways flight, departing Fri, Jan 9 from Washington to Sihanoukville, returning Sun, Jan 25, priced at $1,248 found 23 hours ago
Qatar Airways
Fri, Jan 30 - Sun, Feb 15
IAD
Washington
KOS
Sihanoukville
$1,251 Roundtrip, found 23 hours ago
$1,251
Roundtrip
found 23 hours ago
Select Qatar Airways flight, departing Fri, Jan 30 from Washington to Sihanoukville, returning Sun, Feb 15, priced at $1,251 found 23 hours ago
Qatar Airways
Fri, Jan 9 - Wed, Jan 21
IAD
Washington
KOS
Sihanoukville
$1,278 Roundtrip, found 23 hours ago
$1,278
Roundtrip
found 23 hours ago
Select Qatar Airways flight, departing Fri, Jan 9 from Washington to Sihanoukville, returning Wed, Jan 21, priced at $1,278 found 23 hours ago
Qatar Airways
Mon, Jan 12 - Fri, Jan 30
IAD
Washington
KOS
Sihanoukville
$1,307 Roundtrip, found 23 hours ago
$1,307
Roundtrip
found 23 hours ago
Select Qatar Airways flight, departing Mon, Jan 12 from Washington to Sihanoukville, returning Fri, Jan 30, priced at $1,307 found 23 hours ago
Qatar Airways
Tue, Dec 9 - Thu, Dec 25
IAD
Washington
KOS
Sihanoukville
$1,309 Roundtrip, found 23 hours ago
$1,309
Roundtrip
found 23 hours ago
Select Qatar Airways flight, departing Tue, Dec 9 from Washington to Sihanoukville, returning Thu, Dec 25, priced at $1,309 found 23 hours ago
Qatar Airways
Tue, Dec 9 - Wed, Dec 24
IAD
Washington
KOS
Sihanoukville
$1,312 Roundtrip, found 23 hours ago
$1,312
Roundtrip
found 23 hours ago
Select Qatar Airways flight, departing Tue, Dec 9 from Washington to Sihanoukville, returning Wed, Dec 24, priced at $1,312 found 23 hours ago
Qatar Airways
Fri, Jan 2 - Sun, Jan 18
IAD
Washington
KOS
Sihanoukville
$1,321 Roundtrip, found 23 hours ago
$1,321
Roundtrip
found 23 hours ago
Select Qatar Airways flight, departing Fri, Jan 2 from Washington to Sihanoukville, returning Sun, Jan 18, priced at $1,321 found 23 hours ago
Qatar Airways
Tue, Dec 30 - Tue, Jan 13
IAD
Washington
KOS
Sihanoukville
$1,325 Roundtrip, found 23 hours ago
$1,325
Roundtrip
found 23 hours ago
Select Qatar Airways flight, departing Tue, Dec 30 from Washington to Sihanoukville, returning Tue, Jan 13, priced at $1,325 found 23 hours ago
Qatar Airways
Thu, Dec 4 - Wed, Dec 17
IAD
Washington
KOS
Sihanoukville
$1,328 Roundtrip, found 23 hours ago
$1,328
Roundtrip
found 23 hours ago
Select Qatar Airways flight, departing Thu, Dec 4 from Washington to Sihanoukville, returning Wed, Dec 17, priced at $1,328 found 23 hours ago

Frequently asked questions

How much does a flight from Washington Dulles Intl. Airport (IAD) to Sihanoukville Airport (KOS) cost?
Secure a cheap one-way flight from $913 or cheap return flight from $1,168 from Washington Dulles Intl. Airport (IAD) to Sihanoukville Airport (KOS) 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 Sihanoukville Airport (KOS)?
January is the cheapest month to fly from IAD to KOS. Traveling during an off-peak travel window is often the key to finding better fares.
What is the cheapest airline that flies from Washington Dulles Intl. Airport (IAD) to Sihanoukville Airport (KOS)?
To find the cheapest airline flying from IAD to KOS, use Expedia's filter tool. Tailor your search based on your travel needs, such as preferred carriers and flight duration. You can then sort your results by "Price (lowest to highest)" to see the cheapest flights first.
How many flights per day from Washington Dulles Intl. Airport (IAD) to Sihanoukville Airport (KOS)?
You'll need to catch a flight with a layover if you're traveling from Washington Dulles Intl. Airport (IAD) to Sihanoukville Airport (KOS). There are no daily direct flights on this route. However, just filter your search to include one or more stops to discover an option that works for you.
What day of the week has the most flights from IAD to KOS?
Friday is generally the busiest day for flights, while Tuesday is often the quietest.* Just remember that flight schedules can change based on a range of factors, such as the season and airline.*Busiest/quietest day to travel is based on Expedia flight demand through January to December 2024.
What is the best time to fly from Washington Dulles Intl. Airport (IAD) to Sihanoukville Airport (KOS)?
To land at Sihanoukville Airport (KOS) on time, book a flight that takes off from Washington Dulles Intl. Airport (IAD) before 3 PM. The likelihood of cancellations is 22% higher, on average, for departures after this hour.**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.
Is it cheaper to buy a plane ticket from Washington Dulles Intl. Airport (IAD) to Sihanoukville Airport (KOS) last-minute?
Booking your flight from IAD to KOS right before your trip is typically more expensive. But if you're flexible with your schedule, you could bag a cheap last-minute fare.
Is it cheaper to book an IAD to KOS flight and hotel package?
You can save money by booking an IAD to KOS flight and hotel package compared to booking separately. In fact, travelers could save hundreds of dollars by bundling with Expedia. And it's easy to manage it all in one place. After selecting your ideal flights and accommodations, consider adding extras like tours, activities and car rentals.
Can I cancel or change the date of my flight from Washington Dulles Intl. Airport (IAD) to Sihanoukville Airport (KOS)?
If you reserved your IAD to KOS flight in the last 24 hours, you may be able to cancel or modify it without fees. Depending on the airline and the type of ticket you purchased, additional charges may apply for changes after that time. Airline policies and contact information can be found in your itinerary or confirmation email. Or, visit our Customer Service portal for more details.

Travel information

Origin airport
Washington Dulles Intl.
Destination airport
Sihanoukville
Roundtrip price
$1,168
Distance
9013 mi

Book with confidence

Washington to Sihanoukville Flights

The cheapest times to fly from Washington to Sihanoukville

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 Sihanoukville are during the month of January. You can find some of the cheapest flights from Washington to Sihanoukville with Expedia's search tool and vast selection of airlines.

 

The best time to book a flight from Washington to Sihanoukville

Sunday is one of the best days to book for cheap flights from Washington to Sihanoukville: 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 Sihanoukville

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 Sihanoukville in 2025. You can also book with separate airlines for your outbound and return journeys, from $913 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 Sihanoukville 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 Sihanoukville 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.

 

Washington to Sihanoukville Flights

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*Available to One Key members.