$521 Cheap Flights from Washington (IAD) to Samui Intl. Airport (USM)

View $521 flight on Thu, Apr 23, 2026Opens in a new window

Popular airlines from Washington Dulles Intl. Airport (IAD) to Samui Intl. Airport (USM)

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

Prices were available within the past 7 days and start at $521 for one-way flights and $936 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

United
Wed, Apr 22 - Thu, Apr 30
IAD
Washington
USM
Koh Samui
$936 Roundtrip, found 6 days ago
$936
Roundtrip
found 6 days ago
Select United flight, departing Wed, Apr 22 from Washington to Koh Samui, returning Thu, Apr 30, priced at $936 found 6 days ago
United
Mon, Oct 27 - Mon, Nov 3
IAD
Washington
USM
Koh Samui
$940 Roundtrip, found 1 day ago
$940
Roundtrip
found 1 day ago
Select United flight, departing Mon, Oct 27 from Washington to Koh Samui, returning Mon, Nov 3, priced at $940 found 1 day ago
United
Wed, Apr 22 - Thu, Apr 30
IAD
Washington
USM
Koh Samui
$954 Roundtrip, found 6 days ago
$954
Roundtrip
found 6 days ago
Select United flight, departing Wed, Apr 22 from Washington to Koh Samui, returning Thu, Apr 30, priced at $954 found 6 days ago
United
Mon, Oct 27 - Mon, Nov 3
IAD
Washington
USM
Koh Samui
$959 Roundtrip, found 1 day ago
$959
Roundtrip
found 1 day ago
Select United flight, departing Mon, Oct 27 from Washington to Koh Samui, returning Mon, Nov 3, priced at $959 found 1 day ago
United
Thu, Apr 23 - Sat, May 9
IAD
Washington
USM
Koh Samui
$976 Roundtrip, found 1 day ago
$976
Roundtrip
found 1 day ago
Select United flight, departing Thu, Apr 23 from Washington to Koh Samui, returning Sat, May 9, priced at $976 found 1 day ago
United
Fri, Oct 31 - Tue, Nov 11
IAD
Washington
USM
Koh Samui
$980 Roundtrip, found 3 days ago
$980
Roundtrip
found 3 days ago
Select United flight, departing Fri, Oct 31 from Washington to Koh Samui, returning Tue, Nov 11, priced at $980 found 3 days ago
Etihad Airways
Sun, Apr 26 - Sun, May 17
IAD
Washington
USM
Koh Samui
$1,033 Roundtrip, found 2 days ago
$1,033
Roundtrip
found 2 days ago
Select Etihad Airways flight, departing Sun, Apr 26 from Washington to Koh Samui, returning Sun, May 17, priced at $1,033 found 2 days ago
Turkish Airlines
Mon, Nov 24 - Wed, Dec 3
IAD
Washington
USM
Koh Samui
$1,148 Roundtrip, found 2 days ago
$1,148
Roundtrip
found 2 days ago
Select Turkish Airlines flight, departing Mon, Nov 24 from Washington to Koh Samui, returning Wed, Dec 3, priced at $1,148 found 2 days ago
Qatar Airways
Mon, Oct 27 - Mon, Nov 3
IAD
Washington
USM
Koh Samui
$1,304 Roundtrip, found 1 day ago
$1,304
Roundtrip
found 1 day ago
Select Qatar Airways flight, departing Mon, Oct 27 from Washington to Koh Samui, returning Mon, Nov 3, priced at $1,304 found 1 day ago
Emirates
Sun, Nov 9 - Fri, Nov 21
IAD
Washington
USM
Koh Samui
$1,566 Roundtrip, found 6 hours ago
$1,566
Roundtrip
found 6 hours ago
Select Emirates flight, departing Sun, Nov 9 from Washington to Koh Samui, returning Fri, Nov 21, priced at $1,566 found 6 hours ago

Alternative airports near Koh Samui

Prices were available within the past 7 days. Prices and availability are subject to change.

Select flight to Samui Intl. Airport USM. Cheapest and Closest option available. Average driving time to city center is 31 minutes. Flights from $1,542
USM
Samui Intl. Airport
CheapestClosest
Average driving time to city center31 min
Flights from $1,542

Frequently asked questions

How much does a flight from Washington Dulles Intl. Airport (IAD) to Ko Samui Airport (USM) cost?
Grab a cheap one-way flight from $521 or cheap return flight from $936 from Washington Dulles Intl. Airport (IAD) to Ko Samui Airport (USM) with Expedia. Enter your travel dates and sort by "Price (lowest to highest)" to see our cheapest flight offers on this route.
What is the cheapest month to fly from Washington Dulles Intl. Airport (IAD) to Ko Samui Airport (USM)?
Planning your trip for April can help you save, as it's the cheapest month for flights between IAD and USM. You'll often find the lowest prices during off-peak months.
What is the cheapest airline that flies from Washington Dulles Intl. Airport (IAD) to Ko Samui Airport (USM)?
Expedia's filter tool lets you easily compare different airlines, flight durations and fares all in one place. Tailor the search to your trip, then sort by "Price (lowest to highest)" to see which carrier offers the cheapest IAD to USM flight.
How many flights per day from Washington Dulles Intl. Airport (IAD) to Ko Samui Airport (USM)?
Direct flights from Washington Dulles Intl. Airport (IAD) to Ko Samui Airport (USM) aren't available daily, so you'll need to take a flight with a layover. Explore your options with Expedia's filters. Enter your travel dates and select either "1 Stop" or "2+ Stops."
What day of the week has the most flights from IAD to USM?
You'll usually find Tuesday the quietest day for flights, while Fridays are often the busiest.* However this can vary from season to season and during peak travel times or public holidays.*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 Ko Samui Airport (USM)?
To avoid potential delays on the Washington Dulles Intl. Airport (IAD) to Ko Samui Airport (USM) route, aim to fly before 3 PM. Flights after this time have a 22% higher chance of cancellation.**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 Ko Samui Airport (USM) last-minute?
Booking your flight from IAD to USM right before your trip is typically more expensive. However, if there's some wiggle room with your travel dates and times, you could bag a cheap last-minute fare.
Is it cheaper to book an IAD to USM flight and hotel package?
Compared with arranging hotels and flights separately, booking an IAD to USM flight and hotel package with Expedia could lead to significant savings. What's more, having everything in one convenient place will take the stress out of planning your trip. Simply pick your flights and choose from our extensive range of stays, then personalize your trip with other add-ons like tours, car rentals and activities.
Can I cancel or change the date of my flight from Washington Dulles Intl. Airport (IAD) to Ko Samui Airport (USM)?
If you reserved your IAD to USM flight in the last 24 hours, you may be able to cancel or modify it without fees. Depending on the airline and the fare type you purchased, additional charges may apply for changes beyond that time. Airline policies and contact information can be found in your itinerary or confirmation email. Or, visit our Customer Service portal if you want more information.

Travel information

Origin airport
Washington Dulles Intl.
Destination airport
Samui Intl. Airport
Airlines serving
Air France, Austrian Airlines, British Airways, Emirates, Etihad Airways, KLM, Lufthansa, Qatar Airways, Swiss International Air Lines, Turkish Airlines
Roundtrip price
$936
Distance
9081 mi

Book with confidence

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 April. 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 $521 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.

 

Washington to Samui Intl. Airport Flights
*Available to One Key members.