Ask three contractors in Samui what it costs to build a villa and you will get three numbers per square metre, all of them lower than what you will actually spend. They are not necessarily dishonest. They are quoting the house. Your budget has to cover the project.
The headline number
For 2026, on a normal site with reasonable access, the broad ranges for construction of the villa itself are:
- Simple, local-standard build: roughly 25,000–35,000 THB per m². Adequate for a rental property built to a local market, not to European expectations of detailing.
- Good international standard: roughly 38,000–55,000 THB per m². Proper waterproofing, quality joinery, imported fittings where it matters, a contractor who documents the work.
- High-end / architect-led: 60,000 THB per m² and upwards, with no meaningful ceiling once structural glazing, imported stone and bespoke joinery enter the drawing.
Those ranges move with the exchange rate, steel and cement prices, and how busy the island's good contractors are in any given season. Treat them as a starting frame, not a quotation.
Everything the per-square-metre figure leaves out
This is where projects overrun. In rough order of how often they are forgotten:
Site works and access
Hillside plots are the ones people want and the ones that cost the most to prepare. Cutting a platform, retaining walls, drainage and a driveway steep enough to need engineering can add anywhere from 8% to 25% of the build cost on a difficult slope. On a flat plot near the ring road it can be close to nothing. The same villa on two different plots is not the same project.
Infrastructure connections
Mains water on Samui is not universally reliable and many villas run on a combination of municipal supply, storage tanks and a well, plus filtration. Electricity connection costs depend on distance from the nearest transformer, and on a remote plot that distance is the whole story. Budget for a septic and treatment system that actually meets requirements rather than the cheapest tank available.
Pool, landscaping, boundary
A decent infinity pool with proper structure, overflow tank and plant is a meaningful line item in its own right, not a fitting. Landscaping, walls, gates and outdoor lighting on a sloped plot follow the same logic.
Professional fees
Architect, structural engineer, permit drawings and independent site supervision. Supervision is the one people cut, and it is the one that pays for itself: an independent set of eyes signing off each stage before payment is the main defence against work that has to be redone.
Furniture, fit-out and the rental package
If the villa is going to be rented, it needs to be furnished to the standard of the rate you intend to charge. Air conditioning throughout, outdoor furniture that survives salt air, linen, kitchen, and the audiovisual package guests now expect. This is routinely underestimated by half.
Contingency
Ten percent is the number people write down. Fifteen is the number experienced developers actually hold, and on a complicated site twenty is not excessive. Rain delays in the wet season are a schedule cost as well as a construction one.
A worked frame
Take a 300 m² villa at a good international standard, on a moderate slope, intended for rental:
- Construction at ~45,000 THB/m²: the core of the budget
- Site works and retaining: a meaningful additional percentage, site-specific
- Pool, landscaping, boundary walls: a further significant line
- Utilities, water treatment, backup: fixed costs that do not scale down with a smaller house
- Professional fees and supervision: a percentage of the whole, not of the shell
- Furniture and fit-out to rental standard: sized against your target nightly rate
- Contingency at 15%
The point of setting it out this way is not the arithmetic. It is that the last five lines together are frequently comparable in size to a large part of the construction cost, and they are the lines missing from the number a buyer is quoted at the start.
Payment structure matters as much as price
Never pay ahead of work. A sound schedule ties each payment to a completed, inspected stage — foundations, structure, roof, first fix, second fix, finishes, handover — with a retention of around 5% held for a defects period after completion. A contractor who insists on large front-loaded payments is telling you something about their cash position, and you do not want to be financing it.
A cheap contractor is the most expensive decision available in this market, because you pay for the work twice and the second time is always more urgent.
What we do with these numbers
Before a client commits to a plot, we model the whole project on that specific site: what it costs to make the land buildable, what the villa costs to the standard the target rental rate requires, and what the yield looks like once management, maintenance, taxes and vacancy are taken out. Sometimes the answer is that the plot is beautiful and the project does not work. Better to know that in a spreadsheet than in year two.
General information, not advice. Thai property law is applied case by case and changes over time. Nothing here replaces an opinion from a licensed Thai lawyer on your specific plot, structure and circumstances. Figures are indicative ranges observed in the market, not quotations.
