$735 Cheap Flights from St. Louis (STL) to Samui Intl. Airport (USM)

View $735 flight on Mon, Mar 16, 2026Opens in a new window

Popular airlines from St. Louis Lambert Intl. Airport (STL) to Samui Intl. Airport (USM)

Cheap Flights from St. Louis to Samui Intl. Airport (STL-USM)

Prices were available within the past 7 days and start at $735 for one-way flights and $1,010 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

United
Tue, Mar 17 - Mon, Mar 23
STL
St. Louis
USM
Koh Samui
$1,010 Roundtrip, found 2 days ago
$1,010
Roundtrip
found 2 days ago
Select United flight, departing Tue, Mar 17 from St. Louis to Koh Samui, returning Mon, Mar 23, priced at $1,010 found 2 days ago
United
Sun, Nov 23 - Wed, Nov 26
STL
St. Louis
USM
Koh Samui
$1,100 Roundtrip, found 5 days ago
$1,100
Roundtrip
found 5 days ago
Select United flight, departing Sun, Nov 23 from St. Louis to Koh Samui, returning Wed, Nov 26, priced at $1,100 found 5 days ago
United
Sun, Nov 23 - Wed, Nov 26
STL
St. Louis
USM
Koh Samui
$1,109 Roundtrip, found 5 days ago
$1,109
Roundtrip
found 5 days ago
Select United flight, departing Sun, Nov 23 from St. Louis to Koh Samui, returning Wed, Nov 26, priced at $1,109 found 5 days ago
United
Tue, Mar 17 - Tue, Mar 24
STL
St. Louis
USM
Koh Samui
$1,125 Roundtrip, found 2 days ago
$1,125
Roundtrip
found 2 days ago
Select United flight, departing Tue, Mar 17 from St. Louis to Koh Samui, returning Tue, Mar 24, priced at $1,125 found 2 days ago
United
Mon, Mar 16 - Mon, Mar 23
STL
St. Louis
USM
Koh Samui
$1,136 Roundtrip, found 2 days ago
$1,136
Roundtrip
found 2 days ago
Select United flight, departing Mon, Mar 16 from St. Louis to Koh Samui, returning Mon, Mar 23, priced at $1,136 found 2 days ago
United
Tue, Mar 17 - Sun, Mar 22
STL
St. Louis
USM
Koh Samui
$1,190 Roundtrip, found 2 days ago
$1,190
Roundtrip
found 2 days ago
Select United flight, departing Tue, Mar 17 from St. Louis to Koh Samui, returning Sun, Mar 22, priced at $1,190 found 2 days ago
United
Mon, Mar 16 - Tue, Mar 24
STL
St. Louis
USM
Koh Samui
$1,251 Roundtrip, found 2 days ago
$1,251
Roundtrip
found 2 days ago
Select United flight, departing Mon, Mar 16 from St. Louis to Koh Samui, returning Tue, Mar 24, priced at $1,251 found 2 days ago
United
Mon, Mar 16 - Sun, Mar 22
STL
St. Louis
USM
Koh Samui
$1,292 Roundtrip, found 2 days ago
$1,292
Roundtrip
found 2 days ago
Select United flight, departing Mon, Mar 16 from St. Louis to Koh Samui, returning Sun, Mar 22, priced at $1,292 found 2 days ago
American Airlines
Wed, Mar 18 - Sun, Mar 22
STL
St. Louis
USM
Koh Samui
$1,363 Roundtrip, found 2 days ago
$1,363
Roundtrip
found 2 days ago
Select American Airlines flight, departing Wed, Mar 18 from St. Louis to Koh Samui, returning Sun, Mar 22, priced at $1,363 found 2 days ago
Cathay Pacific
Wed, Nov 26 - Wed, Dec 3
STL
St. Louis
USM
Koh Samui
$1,401 Roundtrip, found 1 day ago
$1,401
Roundtrip
found 1 day ago
Select Cathay Pacific flight, departing Wed, Nov 26 from St. Louis to Koh Samui, returning Wed, Dec 3, priced at $1,401 found 1 day 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 $1,963
USM
Samui Intl. Airport
CheapestClosest
Average driving time to city center31 min
Flights from $1,963

Frequently asked questions

How much does a flight from Lambert-St. Louis Intl. Airport (STL) to Ko Samui Airport (USM) cost?
Snag a cheap one-way flight from $735 or cheap return flight from $1,010 from Lambert-St. Louis Intl. Airport (STL) to Ko Samui Airport (USM) with Expedia. Enter your travel dates and sort by "Price (lowest to highest)" to find our cheapest flight deals on this route.
What is the cheapest month to fly from Lambert-St. Louis Intl. Airport (STL) to Ko Samui Airport (USM)?
March is the cheapest month to fly from STL to USM. Traveling during an off-peak travel window is often the key to finding better deals on flights.
What is the cheapest airline that flies from Lambert-St. Louis Intl. Airport (STL) to Ko Samui Airport (USM)?
Expedia's filter tool lets you easily compare different airlines, flight durations and fares all in one place. Select your preferences, then sort by "Price (lowest to highest)" to find the carrier with the cheapest STL to USM flight.
How many flights per day from Lambert-St. Louis Intl. Airport (STL) to Ko Samui Airport (USM)?
You'll need to take a flight with a layover if you're traveling from Lambert-St. Louis Intl. Airport (STL) to Ko Samui Airport (USM). There are no daily direct flights on this route. However, just filter your search to include one or two stops to find the best option for your trip.
What day of the week has the most flights from STL to USM?
Friday is usually the busiest day for flights, while Tuesday is often the quietest.* Keep in mind that flight schedules can change depending on various factors, including 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 Lambert-St. Louis Intl. Airport (STL) to Ko Samui Airport (USM)?
To avoid possible delays on the Lambert-St. Louis Intl. Airport (STL) to Ko Samui Airport (USM) route, fly before 3 PM. Later flights 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.
Is it cheaper to buy a plane ticket from Lambert-St. Louis Intl. Airport (STL) to Ko Samui Airport (USM) last-minute?
Waiting until just before your trip to book a flight from STL to USM generally means paying more. Although you may find some last-minute discounts, there's no guarantee. Be flexible with your travel plans to maximize your chances of landing a bargain.
Is it cheaper to book a STL to USM flight and hotel package?
You'll typically save money by booking a STL to USM flight and hotel package compared to booking separately. In fact, you could save hundreds of dollars by bundling with Expedia. And it's simple to manage everything in one convenient place. Once you've selected your ideal accommodations and flights, consider adding extras including activities, tours and car rentals.
Can I cancel or change the date of my flight from Lambert-St. Louis Intl. Airport (STL) to Ko Samui Airport (USM)?
Usually, it's possible to cancel or reschedule your STL to USM flight. However, if the booking was made more than 24 hours ago, additional fees may apply. Check your airline's policies in your itinerary to see what changes are possible and whether any costs are involved. You'll also find more information on our Customer Service portal.

Travel information

Origin airport
Lambert-St. Louis Intl.
Destination airport
Samui Intl. Airport
Airlines serving
Cathay Pacific
Roundtrip price
$1,009
Distance
9032 mi

Book with confidence

St. Louis to Samui Intl. Airport Flights

The cheapest times to fly from St. Louis 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 St. Louis to Samui Intl. Airport are during the month of March. You can find some of the cheapest flights from St. Louis to Samui Intl. Airport with Expedia's search tool and vast selection of airlines.

 

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

Sunday is one of the best days to book for cheap flights from St. Louis 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 St. Louis 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 St. Louis to Samui Intl. Airport in 2025. You can also book with separate airlines for your outbound and return journeys, from $735 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 St. Louis 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 St. Louis 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.

 

St. Louis to Samui Intl. Airport Flights
*Available to One Key members.