Land Measurement in Thailand

Land measurement in Thailand is governed by a unique combination of traditional Thai units, formal cadastral surveys, and land registration procedures under the Land Code B.E. 2497 (1954). Accurate land measurement is essential for ownership, transfer, development, valuation, and boundary enforcement. Misunderstandings regarding units of measurement or discrepancies in surveyed dimensions can lead to costly boundary disputes, development errors, or registration issues.

This article provides a comprehensive overview of Thailand’s land measurement system, including the legal units of area, survey practices, mapping systems, and implications for property transactions.

I. Legal Framework and Authority

Land measurement and cadastral surveying in Thailand are under the jurisdiction of the Department of Lands (DOL), part of the Ministry of Interior. The DOL oversees:

• Title deed issuance

• Surveying and mapping

• Registration of rights and encumbrances

• Boundary certification

All official measurements in land title documents are based on ground surveys, and the surveyed size recorded is binding for legal and transactional purposes.

The system is derived from the Cadastral Survey System, refined over decades and transitioning toward digital mapping under Thailand’s Land Information System (LIS).

II. Traditional Thai Land Measurement Units

Thailand uses a non-metric, traditional system for measuring land area. Although metric conversion is possible, most land transactions and title deeds (Chanote, Nor Sor 3, etc.) use Thai units:

Breakdown:

• 1 Rai = 1,600 m² = 0.16 hectares

• 6.25 Rai = 1 hectare

• 1 Acre = Approximately 2.5 Rai

Smaller units are rarely used in legal documents but may be encountered in informal contexts:

• Tarang meter (ตร.ม.) = Square meter (for condos or buildings)

When buying or selling land, Thai documents will usually list the size in Rai – Ngan – Wah² format. For example:

• 2 Rai, 3 Ngan, 25 Wah² = 3,300 m²

III. Land Title Deeds and Recorded Measurements

Thailand recognizes several types of land documents, each carrying different legal weight:

1. Chanote (Nor Sor 4 Jor) – Fully surveyed and GPS-mapped; strongest land title; suitable for sale and development.

2. Nor Sor 3 Gor – Surveyed, but not fully GPS; transferrable but requires public notice.

3. Nor Sor 3 – Roughly surveyed; usable, but boundaries may not be physically marked.

4. Sor Kor 1 / Por Bor Tor 5 – Claims of use; not legally transferrable or recognized for sale; may be upgraded.

Each deed will list:

• Land area (in Thai units)

• Survey map or sketch with bearings and length

• Neighboring plot numbers or landmarks

• Boundary marker references (หลักเขต)

Only Chanote titles are guaranteed accurate in area and boundaries, as they are produced through triangulated GPS surveys and permanent boundary markers.

IV. Surveying Process and Accuracy

The Department of Lands applies the cadastral survey methodology, including:

1. Baseline Measurements

   • Initial survey using fixed reference points in a national geodetic network

2. Triangulation and GPS

   • Modern surveys use Global Navigation Satellite System (GNSS) for high accuracy

3. Physical Boundary Marking

   • Cement boundary posts (Lak Chet) with unique reference numbers are installed at corners

4. Plot Mapping

   • Maps with scaled drawings, including orientation, area, and plot number, are attached to title deeds

Accuracy levels vary depending on the title type:

• Chanote: ± 1–2 centimeters

• Nor Sor 3 Gor: less precise; subject to overlaps

• Nor Sor 3: area is approximate; may not match ground reality

V. Measurement Discrepancies and Legal Implications

Disputes often arise when:

• Measured area on the ground differs from that stated on the deed

• Boundary markers are missing or displaced

• Neighboring landowners encroach onto each other’s land

• Natural features (e.g., riverbanks) change over time

Remedies:

• Submit a request for land resurvey at the Land Office

• File a complaint to Land Inspection Division

• Use land adjudication process (พิสูจน์สิทธิ์ในที่ดิน) in cases of overlap

• If unresolved, a civil lawsuit may be required to determine ownership or boundaries

Thai courts generally favor the title deed dimensions, especially Chanote titles, unless strong evidence of error or fraud is presented.

VI. Professional Roles in Land Measurement

Professionals involved include:

• Land Surveyors (DOL-certified) – Only licensed surveyors can conduct official measurements for title registration.

• Engineers or Architects – May conduct private surveys for planning, construction, or valuation, but results have no legal weight unless certified by DOL.

• Lawyers – Advise clients on boundary disputes, documentation, and litigation.

Unauthorized surveys are not legally binding and cannot be used to alter registered land records.

VII. Digital Transformation and GIS

The Thai government is advancing the Land Information System (LIS), aiming to digitize land records and integrate GIS mapping tools. Key goals include:

• Eliminating duplicate or overlapping titles

• Providing online access to cadastral maps

• Facilitating efficient land transactions and valuation

• Increasing tax compliance under the Land and Building Tax Act

This system improves reliability, reduces corruption, and speeds up land-related procedures.

VIII. Land Measurement in Development Projects

In real estate development:

• Plot subdivision requires a resurvey and issuance of new Chanote titles

• Road access and easement rights must be demarcated

• Minimum plot sizes may apply (e.g., under the Land Development Act)

For condominiums, land is measured in square meters, but the entire project’s land plot will still be registered in Rai-Ngan-Wah² and affect the unit ratio and ownership share.

IX. Land Measurement and Foreign Ownership

Foreigners cannot own land in Thailand (except under special laws), but:

• Condominiums are sold by square meter

• Leasehold agreements (30 years) should clearly describe leased area using correct Thai measurements

• Foreign investors through BOI or IEAT may hold land, but title survey compliance is still mandatory

Clarity in land measurement is crucial for enforceable contracts, especially for long-term leases or surface rights (superficies).

Conclusion

Land measurement in Thailand is a foundational aspect of land law, ownership security, and dispute resolution. The system’s reliance on traditional units, combined with cadastral surveying and centralized registration, ensures transparency but also imposes strict procedural rules.

Property owners, buyers, and investors must understand the implications of title types, the accuracy of surveyed areas, and the legal consequences of discrepancies. When in doubt, it is essential to consult a qualified land surveyor or lawyer and to verify land data through the Department of Lands.