$542 Cheap Flights from Washington (DCA) to Samui Intl. Airport (USM)

View $542 flight on Wed, Aug 27, 2025Opens in a new window

Popular airlines from Ronald Reagan Washington National Airport (DCA) to Samui Intl. Airport (USM)

Cheap Flights from Washington to Samui Intl. Airport (DCA-USM)

Prices were available within the past 7 days and start at $542 for one-way flights and $932 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

United
Thu, Sep 4 - Mon, Sep 29
DCA
Washington
USM
Koh Samui
$932 Roundtrip, found 1 day ago
$932
Roundtrip
found 1 day ago
Select United flight, departing Thu, Sep 4 from Washington to Koh Samui, returning Mon, Sep 29, priced at $932 found 1 day ago
United
Mon, Aug 18 - Mon, Aug 25
DCA
Washington
USM
Koh Samui
$940 Roundtrip, found 3 days ago
$940
Roundtrip
found 3 days ago
Select United flight, departing Mon, Aug 18 from Washington to Koh Samui, returning Mon, Aug 25, priced at $940 found 3 days ago
United
Mon, Aug 18 - Mon, Aug 25
DCA
Washington
USM
Koh Samui
$946 Roundtrip, found 3 days ago
$946
Roundtrip
found 3 days ago
Select United flight, departing Mon, Aug 18 from Washington to Koh Samui, returning Mon, Aug 25, priced at $946 found 3 days ago
United
Mon, Aug 18 - Mon, Aug 25
DCA
Washington
USM
Koh Samui
$949 Roundtrip, found 3 days ago
$949
Roundtrip
found 3 days ago
Select United flight, departing Mon, Aug 18 from Washington to Koh Samui, returning Mon, Aug 25, priced at $949 found 3 days ago
United
Mon, Aug 18 - Mon, Aug 25
DCA
Washington
USM
Koh Samui
$950 Roundtrip, found 3 days ago
$950
Roundtrip
found 3 days ago
Select United flight, departing Mon, Aug 18 from Washington to Koh Samui, returning Mon, Aug 25, priced at $950 found 3 days ago
United
Mon, Aug 18 - Mon, Aug 25
DCA
Washington
USM
Koh Samui
$955 Roundtrip, found 3 days ago
$955
Roundtrip
found 3 days ago
Select United flight, departing Mon, Aug 18 from Washington to Koh Samui, returning Mon, Aug 25, priced at $955 found 3 days ago
United
Mon, Aug 18 - Mon, Aug 25
DCA
Washington
USM
Koh Samui
$958 Roundtrip, found 3 days ago
$958
Roundtrip
found 3 days ago
Select United flight, departing Mon, Aug 18 from Washington to Koh Samui, returning Mon, Aug 25, priced at $958 found 3 days ago
United
Mon, Aug 18 - Mon, Aug 25
DCA
Washington
USM
Koh Samui
$960 Roundtrip, found 3 days ago
$960
Roundtrip
found 3 days ago
Select United flight, departing Mon, Aug 18 from Washington to Koh Samui, returning Mon, Aug 25, priced at $960 found 3 days ago
United
Mon, Aug 18 - Mon, Aug 25
DCA
Washington
USM
Koh Samui
$964 Roundtrip, found 3 days ago
$964
Roundtrip
found 3 days ago
Select United flight, departing Mon, Aug 18 from Washington to Koh Samui, returning Mon, Aug 25, priced at $964 found 3 days ago
Cathay Pacific
Sun, Sep 7 - Sat, Sep 27
DCA
Washington
USM
Koh Samui
$1,862 Roundtrip, found 1 day ago
$1,862
Roundtrip
found 1 day ago
Select Cathay Pacific flight, departing Sun, Sep 7 from Washington to Koh Samui, returning Sat, Sep 27, priced at $1,862 found 1 day ago
Flights from Washington (DCA) to Samui Intl. Airport (USM)
Origin airport
Ronald Reagan Washington National
Destination airport
Samui Intl. Airport
Airlines serving
Cathay Pacific
Roundtrip price
$931
Distance
9087 mi

Washington to Samui Intl. Airport Flights

The cheapest times to fly from Washington to Samui Intl. Airport

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

 

The best time to book a flight from Washington to Samui Intl. Airport

Sunday is one of the best days to book for cheap flights from Washington to Samui Intl. Airport: 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 Samui Intl. Airport

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 Samui Intl. Airport in 2025. You can also book with separate airlines for your outbound and return journeys, from $542 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 Samui Intl. Airport 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 Samui Intl. Airport 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 Ronald Reagan Washington National Airport (DCA) to Ko Samui Airport (USM) cost?
Secure a cheap one-way flight from $542 or cheap return flight from $932 from Ronald Reagan Washington National Airport (DCA) to Ko Samui Airport (USM) with Expedia. Enter your travel dates and sort by "Price (lowest to highest)" to see our cheapest flight deals on this route.
What is the cheapest month to fly from Ronald Reagan Washington National Airport (DCA) to Ko Samui Airport (USM)?
Planning your getaway for September can help you save, as it's the cheapest month for flights between DCA and USM. You'll often find the lowest fares during off-peak months.
What is the cheapest airline that flies from Ronald Reagan Washington National Airport (DCA) to Ko Samui Airport (USM)?
Expedia's filter tool lets you easily compare airlines, flight times and fares all in one place. Customize the search to your preferences, then sort by "Price (lowest to highest)" to find out which carrier offers the cheapest DCA to USM flight.
How many flights per day from Ronald Reagan Washington National Airport (DCA) to Ko Samui Airport (USM)?
Direct flights from Ronald Reagan Washington National Airport (DCA) to Ko Samui Airport (USM) aren't available daily, so you'll have to take a flight with a layover. Explore your options with Expedia's filters. Enter your travel dates and choose either "1 Stop" or "2+ Stops."
What day of the week has the most flights from DCA to USM?
Typically you'll find the greatest selection of flight options on a Friday. Tuesdays tend to be the quietest.* However, this can vary depending on the time of year, carrier and other factors.*Busiest/quietest day to travel is based on Expedia flight demand through January to December 2024.
What is the best time to fly from Ronald Reagan Washington National Airport (DCA) to Ko Samui Airport (USM)?
To land at Ko Samui Airport (USM) on schedule, opt for a flight that leaves Ronald Reagan Washington National Airport (DCA) before 3 PM. The chance 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 Ronald Reagan Washington National Airport (DCA) to Ko Samui Airport (USM) last-minute?
Waiting until just before your departure to book a ticket from DCA to USM often results in higher prices. While you may find some last-minute offers, they aren't always guaranteed. Allow some flexibility in your schedule to maximize your chances of snagging a bargain.
Is it cheaper to book a DCA to USM flight and hotel package?
Opting for a DCA to USM flight and hotel package is usually cheaper than booking separately. With Expedia, you can enjoy the ease of organizing your trip all in one place. Select from our wide range of accommodations and then add car rentals, flights and activities 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 Ronald Reagan Washington National Airport (DCA) to Ko Samui Airport (USM)?
In most instances, you can cancel or modify your DCA to USM flight. However, additional fees may apply, especially if your booking was made more than 24 hours ago. Double-check your itinerary for the airline's rules and fees on flight changes, or if you'd like more details, visit our Customer Service portal.

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*Available to One Key members.