$1,325+ Cheap flights from Dulles Intl (IAD) to Ko Samui (USM)
This is the cheapest round-trip flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 1/9. Fares are subject to change and may not be available on all flights or dates of travel.
Find cheap flights from Dulles Intl to Ko Samui with Cheapflights
1. Tell us where you want to go
Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”2. Select your favorite providers
We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.3. Compare prices and book
Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.Cheap flight deals from Dulles Intl to Ko Samui
Cheapest flights from Dulles Intl to Ko SamuiExplore the most affordable flight options available from Dulles Intl to Ko Samui. Find the lowest fares from popular airlines and budget airlines, with prices last updated on diciembre 12, 2025.
Explore the most affordable flight options available from Dulles Intl to Ko Samui. Find the lowest fares from popular airlines and budget airlines, with prices last updated on diciembre 12, 2025.
This Ovago deal was found by Cheapflights users on 12/11. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Ovago is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Find flight deals from Dulles Intl to Ko Samui
Discover tips and strategies to find the most affordable flight options for your journey from Dulles Intl (IAD) to Ko Samui (USM). 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 diciembre 12, 2025.
Most accurate provider | Ovago 2 stars |
|---|---|
Most trusted provider | AranGrant 3 stars |
Round-trip from | $1,018 (Gotogate) |
Cheapflights Fare Finder
Use the filters below to find and compare flights from Washington, D.C. Dulles Intl Airport to Ko Samui that are best for you.
Fly from
Fly to
Route
Depart
Return
Price
Washington, D.C.Ko Samui
IAD - USM
IADUSM
Washington, D.C. Dulles Intl
mié. 1/7
1:30 pm-8:25 am
2 stops54h 55m
Ko Samui
mié. 1/21
9:10 pm-7:20 pm
2 stops34h 10m
Washington, D.C.Ko Samui
IAD - USM
IADUSM
Washington, D.C. Dulles Intl
lun. 1/5
2:35 pm-8:05 am
2 stops29h 30m
Ko Samui
mié. 1/21
7:15 am-9:05 am
2 stops61h 50m
Washington, D.C.Ko Samui
IAD - USM
IADUSM
Washington, D.C. Dulles Intl
sáb. 1/10
2:35 pm-8:10 am
2 stops29h 35m
Ko Samui
mar. 1/20
9:00 am-9:05 am
2 stops36h 05m
Washington, D.C.Ko Samui
IAD - USM
IADUSM
Washington, D.C. Dulles Intl
jue. 1/8
2:35 pm-8:05 am
2 stops29h 30m
Ko Samui
mar. 1/20
5:40 pm-9:05 am
2 stops27h 25m
Washington, D.C.Ko Samui
IAD - USM
IADUSM
Washington, D.C. Dulles Intl
lun. 1/5
2:35 pm-7:45 am
2 stops29h 10m
Ko Samui
mar. 1/20
5:25 pm-9:05 am
2 stops27h 40m
Washington, D.C.Ko Samui
IAD - USM
IADUSM
Washington, D.C. Dulles Intl
mar. 1/6
2:35 pm-6:40 pm
2 stops40h 05m
Ko Samui
mié. 1/21
7:15 am-9:05 am
2 stops61h 50m
Washington, D.C.Ko Samui
IAD - USM
IADUSM
Washington, D.C. Dulles Intl
dom. 1/4
2:35 pm-9:20 pm
2 stops42h 45m
Ko Samui
mié. 1/21
7:15 am-9:05 am
2 stops61h 50m
Washington, D.C.Ko Samui
IAD - USM
IADUSM
Washington, D.C. Dulles Intl
vie. 1/9
2:35 pm-7:50 pm
2 stops41h 15m
Ko Samui
dom. 1/18
7:55 am-9:05 am
2 stops37h 10m
Washington, D.C.Ko Samui
IAD - USM
IADUSM
Washington, D.C. Dulles Intl
jue. 1/8
2:35 pm-8:05 am
2 stops29h 30m
Ko Samui
sáb. 1/24
1:25 pm-9:05 am
2 stops31h 40m
Washington, D.C.Ko Samui
IAD - USM
IADUSM
Washington, D.C. Dulles Intl
mar. 1/6
2:35 pm-10:35 am
2 stops32h 00m
Ko Samui
lun. 1/19
7:55 am-9:05 am
2 stops61h 10m
Compare providers for flights from Dulles Intl to Ko Samui
Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.
Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from Dulles Intl to Ko Samui in December.
| Provider | Price Accuracy | Trust Score* |
|---|---|---|
| Price Accuracy2 stars | Trust Score*2 stars | |
| Price Accuracy2 stars | Trust Score*3 stars |
- Most accurate provider: When it comes to deals on Washington, D.C. Dulles Intl Airport-Ko Samui flights, users find the pricing of Ovago to be most consistent on Cheapflights vs. Ovago Users can find the same prices on Washington, D.C. Dulles Intl Airport-Ko Samui flight deals on Cheapflights vs. Ovago 90-95% of the time. Price accuracy is based on data collected from Washington, D.C. Dulles Intl Airport-Ko Samui flight searches over the past month and is updated monthly.
- Most trusted provider: When it comes to deals on Washington, D.C. Dulles Intl Airport-Ko Samui flights, Cheapflights users trust AranGrant the most. AranGrant has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for Washington, D.C. Dulles Intl Airport-Ko Samui flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.
Best time to book a flight from Dulles Intl to Ko Samui
Have a flexible travel schedule? Discover the best time to fly to Ko Samui from Dulles Intl with our price prediction graph.
Cheapflights Insights
Everything you need to know about your flight from Washington, D.C. Dulles Intl Airport to Ko Samui
What is the cheapest time of day to fly from IAD to USM?
It’s optimal to fly from Washington, D.C. Dulles Intl Airport to Ko Samui in the morning. By choosing this option you can save up to 10% on the cost of your flight, compared to a flight in the afternoon.
What is the cheapest day to fly from Washington, D.C. Dulles Intl Airport to Ko Samui?
Travelers seeking maximum savings on their Washington, D.C. Dulles Intl Airport to Ko Samui flight should consider departing on Monday at noon when fares are most often at their lowest. Saturday mornings flights should be avoided if possible as fares are typically the most expensive at this time.
How often are flights from Washington, D.C. to Ko Samui delayed?
About 19% of weekly flights between Washington, D.C. and Ko Samui have experienced delays in the past year, with the average delay time being 77 minutes.
What is the most punctual flight time for Washington, D.C. to Ko Samui flights?
Historically, flights departing in the morning are less likely to be delayed, whereas flights leaving at night tend to experience delays more often.
What day of the week experiences the fewest flight delays on this route?
Friday tends to have the lowest number of delays on this route, whereas Thursday has historically faced a higher average of delays compared to other days of the week.
Which airline has the best punctuality record on Washington, D.C. to Ko Samui flights?
Over the last year, Southwest have had the lowest number of delays on this route, with just 29% of flights being delayed.