Koh Samui Airport (USM) handled approximately 2.1 million passengers in 2024, and per market estimates that figure crossed 2.3 million in 2025. USM is the island's only commercial airport and has been privately operated since 1989. Its constrained infrastructure is one of the structural factors our analysts track most closely when modelling Koh Samui property values.
In 2026, the airport expansion debate has gained new momentum. The Thai government has formally commissioned a feasibility study for a second, publicly owned airport on the island, while the private USM operator is running its own terminal modernisation programme in parallel. Below we set out the factual status of both projects, their realistic timelines, and the measurable impact on property prices across Koh Samui's key districts.
Quick answer
- USM is privately owned and operated under a concession tied to the Bangkok Airways group. Terminal capacity is estimated at 3 million passengers per year, meaning the facility is approaching saturation within 2-3 years at current growth rates
- The Thai Department of Civil Aviation (DCA) approved a feasibility study for a second public airport on Koh Samui in 2024. As of 2026, site selection is ongoing, with the Lamai and Hua Thanon area in the island's south being assessed. No construction start date has been set
- The private USM operator has announced a terminal expansion adding approximately 30% more operational floor space, targeted for completion by end-2027
- Based on our estimates, land prices within 5 km of the most likely second-airport locations have increased 12-18% over the past 18 months, compared with an island-wide average of 8-10%
- USM currently has no direct intercontinental routes. Reaching Koh Samui from Europe requires a minimum of two connections (typically via Bangkok, then USM, or via Surat Thani with a ferry transfer)
- Infrastructure promises carry real risk: Thai public infrastructure projects have historically run 2-4 years behind original schedules, a pattern we weight explicitly in our valuations
Options and scenarios
Scenario A: USM terminal modernisation (highest probability, 2026-2028 horizon)
The private operator is already underway with a passenger terminal expansion. The scope includes an enlarged check-in zone, 4 additional check-in counters, and an expanded aircraft apron. The runway, at 2,100 m, stays unchanged - meaning wide-body aircraft remain unable to use USM regardless of terminal upgrades. Funding is entirely private.
For the property market, this scenario implies moderate demand growth. Daily flight movements are expected to rise from roughly 30-35 to 42-45, improving island accessibility primarily on the Bangkok-Samui corridor. The districts most directly affected are Bophut and Maenam on the north coast, which sit closest to the existing airport.
Scenario B: Second public airport (2030+ horizon)
The DCA feasibility study is evaluating sites in the island's south. The proposed runway length of 2,800-3,000 m would allow wide-body jets such as the Boeing 787 and Airbus A350 to operate, and could theoretically support direct European services. The estimated budget is 15-25 billion THB (based on our estimates, approximately 430-710 million USD at Q1 2026 exchange rates), to be financed through a combination of state funds and a public-private partnership (PPP) structure.
If this project reaches completion, the island's competitive dynamics shift materially. Lamai and the Hua Thanon area would sit in the primary influence zone. Drawing on analogies from the Chiang Mai airport expansion of 2010-2015, our analysts estimate that property prices within 10 km of the new airport could rise 25-40% within three years of opening.
Scenario C: Status quo (no material change)
If both projects face prolonged delays or cancellation, Koh Samui retains its current infrastructure constraints. In this scenario the island loses competitive ground against Phuket, which operates an international airport with capacity of approximately 18 million passengers per year and receives direct flights from Europe. Property price growth on Samui would likely track below the Thai national average.
Comparison table
| Parameter | Scenario A: USM Modernisation | Scenario B: Second Public Airport | Scenario C: Status Quo |
|---|---|---|---|
| Completion horizon | 2027 | 2030-2033 (estimated) | No change |
| Budget | Approx. 2 bn THB (private) | 15-25 bn THB (PPP) | 0 |
| Runway length | 2,100 m (unchanged) | 2,800-3,000 m | 2,100 m |
| Wide-body aircraft | No | Yes | No |
| Annual capacity | Approx. 3.5 mn pax | Approx. 8-10 mn pax | Approx. 3 mn pax |
| Price impact - 5 km zone | +10-15% by 2028 | +25-40% by 2036 | +3-5% (inflation only) |
| Primary beneficiary districts | Bophut, Maenam | Lamai, Hua Thanon | None distinct |
| Status as of 2026 | Works in progress | Feasibility study | - |
| Delay risk | Low | High | - |
Risks and mistakes
Pricing in an infrastructure promise before it is delivered is the single most common valuation error we observe in this market. The pattern repeats: a major project announcement pushes land prices up 6-12 months ahead of any groundbreaking, then a multi-year development period erodes returns for buyers who paid the announcement premium.
Specific risks we are tracking for 2026:
- Regulatory risk. USM's private monopoly is an active political topic in Thailand. Any renegotiation of the concession terms could affect the economics of the ongoing terminal upgrade and the appetite for a parallel public airport
- Environmental risk. Koh Samui covers just 228 sq km. A new airport requires an Environmental Impact Assessment (EIA), which has historically delayed comparable projects on Thai islands by 2-5 years. We treat this as a near-certain source of schedule slippage for Scenario B
- Currency risk. Property transactions on Koh Samui are denominated in Thai baht. The THB/USD rate adds a layer of exposure for international buyers, and this should be factored into total return calculations from the outset
- Overpricing risk. In our data sets, a portion of land listings in the Lamai and Hua Thanon corridor already embeds a 'future airport' premium of 15-20% above fundamental value. We recommend discounting that premium by at least half until a building permit and signed construction contracts are in place
- Comparative risk. Phuket delivers functioning international airport infrastructure today. Any cross-island investment comparison must account for this gap in the discount rate applied to Koh Samui's longer-dated upside
How we weight these scenarios in valuations: projects at the feasibility study stage receive a probability weight of 0.2-0.3 (likelihood of delivery on the stated timeline). Projects with issued building permits and signed contracts move to 0.7-0.8. As of 2026, the USM terminal modernisation carries a weight of 0.75 in our models; the second public airport carries 0.25.
FAQ
Is Koh Samui Airport being expanded in 2026?
Partly. The private operator is actively modernising the passenger terminal, targeting a 15-20% capacity increase. The runway stays at 2,100 m. Separately, the Thai DCA is running a feasibility study for a second, public airport - but that project is at an early planning stage with no confirmed location or funding.
When could a second airport on Koh Samui realistically open?
Based on our estimates and the historical pacing of comparable Thai infrastructure projects, the earliest realistic opening would be 2031-2033, contingent on a positive feasibility outcome, EIA approval, and secured financing. A 2-4 year delay beyond any announced target should be treated as a base case, not a tail risk.
How does the airport situation affect Koh Samui property prices?
The USM terminal upgrade is likely to support a 10-15% price increase in Bophut and Maenam by 2028 through improved accessibility. A completed second airport in the south would have a much stronger effect - our analysts estimate 25-40% appreciation within 10 km of the site over the three years following opening, based on analogies from other Thai island and regional airport expansions.
Should investors buy land near the proposed second airport site now?
We monitor this segment and already observe speculative premiums in the Lamai and Hua Thanon corridor. The project remains at the feasibility study stage, not an approved investment. Buying purely on the infrastructure promise carries a real risk of capital being tied up for many years before any material price catalyst materialises.
How does USM compare with Phuket International Airport?
Phuket International (HKT) operates with annual capacity of approximately 18 million passengers, a 3,000 m runway, and direct connections to European and Middle Eastern hubs. USM handles roughly 2.3 million passengers on a 2,100 m strip with no wide-body capability. This infrastructure gap is one structural reason why comparable coastal properties in Phuket trade at a 30-50% premium per sq m relative to equivalent Koh Samui locations.
Which Koh Samui districts benefit most from each scenario?
Under Scenario A (USM modernisation), Bophut and Maenam on the north coast stand to gain most, given their proximity to the existing airport. Under Scenario B (second southern airport), Lamai and Hua Thanon would be the primary beneficiaries. Western districts such as Lipa Noi and Taling Ngam have limited direct exposure in either scenario.
Will the private airport monopoly on Koh Samui change?
The USM concession is open-ended - the airport was built on private land and the operating rights have no fixed expiry. Construction of a second public airport would represent a de facto break of the monopoly. As of 2026, there are no formal decisions on changing USM's status, though the debate is ongoing in Thai aviation policy circles.
How does airport infrastructure risk affect property valuation methodology?
In our valuation framework, we apply probability weights to infrastructure scenarios rather than discounting them at face value. A project at feasibility study stage receives a weight of 0.2-0.3; one with confirmed permits and contracts receives 0.7-0.8. We then model the price impact of each scenario separately and take a weighted average, rather than assuming the optimistic case as a baseline.
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