Land Measurement in Thailand

Land measurement in Thailand is governed by a unique traditional system that differs from the metric and imperial systems used internationally. The land administration framework is highly centralized and managed by the Department of Lands under the Ministry of Interior. Accurate land measurement is essential for title registration, property transactions, development planning, and taxation. Errors or misinterpretations in land dimensions and title boundaries are common sources of legal disputes, especially in areas where surveying technologies or cadastral records are inconsistent or outdated.

II. The Thai Land Measurement System

Thailand uses a traditional area measurement system based on the units of:

• Wah (วา): a linear unit of measurement (1 wah = 2 meters)

• Square Wah (Tarang Wah, ตารางวา): the basic area unit (1 square wah = 4 square meters)

• Ngan (งาน): 1 ngan = 100 square wah = 400 square meters

• Rai (ไร่): 1 rai = 4 ngan = 1,600 square meters

Conversion Table:

This structure is non-decimal, making conversions non-intuitive. Precision is required in land contracts, cadastral maps, and title deeds.

III. Legal Framework and Authorities

A. Governing Statutes

1. Land Code Act B.E. 2497 (1954)

2. Land Survey Act B.E. 2478 (1935)

3. Ministerial Regulations under the Department of Lands

B. Relevant Government Agencies

• Department of Lands (DOL): manages land title registration and measurement standards.

• Royal Thai Survey Department (RTSD): responsible for geodetic control, triangulation points, and aerial survey data.

• Provincial and District Land Offices: implement measurement at the local level and maintain cadastral records.

IV. Land Titles and Measurement Accuracy

The type of land title directly affects the accuracy and legal reliability of the stated measurements.

A. Chanote (Nor Sor 4 Jor)

• Most secure title, based on GPS-surveyed coordinates and recognized as full ownership.

• Accurately surveyed and monumented with land boundary markers.

• Area measurement and boundary lines are legally precise and enforceable.

B. Nor Sor 3 Gor (NS3G)

• Recognized legal usage right with a clear map but not yet fully GPS-integrated.

• Coordinates are surveyed but not fixed with permanent markers.

• May contain minor deviations in land size or placement.

C. Nor Sor 3 (NS3)

• Land usage right issued without precise survey; boundaries are described textually, not mapped with precision.

• Susceptible to boundary overlap and measurement disputes.

D. Sor Kor 1, Por Bor Tor 5, and Other Informal Documents

• Informal or administrative recognition of occupation.

• No reliable measurement or legal enforceability.

• Cannot be sold or transferred through the Land Office.

V. Land Surveying Procedures

Land surveying is overseen by certified DOL officers, and private surveyors cannot perform official measurements for registration purposes. Key steps include:

1. Application for Measurement or Subdivision

   • Must be filed at the local Land Office.

   • Requires copy of title deed and ID of owner.

2. Field Survey

   • DOL surveyors visit the property with total station/GPS tools.

   • Corner posts (or “luk baan”) are located or newly planted.

   • Adjacent landowners may be called to witness the survey.

3. Preparation of Survey Plan

   • A sketch map (rubthang) is drawn and attached to the title deed.

   • The map includes plot number, area, adjacent plots, and road access.

4. Public Posting

   • For subdivision or consolidation, the Land Office posts a 30-day notice to allow objections.

5. Registration and Title Amendment

   • The title deed is updated to reflect the new measurement or configuration.

Note: Survey data is tied to the Thai national geodetic datum, not always aligned with GPS coordinates from commercial mapping systems.

VI. Common Issues in Measurement and Boundary Disputes

A. Overlapping Boundaries

• Common in rural or hillside areas where NS3 or NS3G titles are based on old surveys or manual sketches.

• May require resurvey by the DOL or court intervention.

B. Encroachment

• Adjacent landowners may have built over boundary lines, leading to disputes.

• Survey and aerial photos are essential in litigation.

C. Discrepancies Between Title and Physical Area

• The title may state “1 rai, 2 ngan, 10 wah²,” but actual land size may be more or less.

• Thai courts recognize the title’s surveyed area, but physical possession may influence disputes.

D. Servitudes and Easements

• Not always mapped on the title, especially in NS3 titles.

• Access paths may exist in practice but not legally recorded.

VII. Land Subdivision and Consolidation

To divide or merge plots:

• Owner must apply for subdivision (phai din) or consolidation (rub din).

• Survey must confirm that each resulting parcel meets minimum area requirements (often ≥50 square wah).

• Zoning laws may restrict subdivision in agricultural or conservation areas.

Municipalities or Land Offices may deny applications based on:

• Inadequate road access

• Violation of zoning plans

• Disputes among co-owners

VIII. Measurement in Property Sales and Leases

All land sales, leases over 3 years, and mortgage registrations must refer to land area based on:

• Exact rai-ngan-wah² notation

• Land title deed number

• Cadastral map reference

Contracts should also include:

• Per square wah price or total sale price

• Responsibility for area discrepancies (buyer or seller)

• Provisions for remeasurement or refunds

In leasing arrangements, especially for condominiums or commercial land, clarity in square meter usage (derived from rai/ngan/wah²) is essential to avoid rental disputes.

IX. Cadastral Modernization and GIS Integration

Thailand has begun integrating Geographic Information System (GIS) and GNSS-based technologies into land management. Pilot projects for:

• Digital cadastral mapping

• Online land parcel lookup

• Mobile-friendly property verification tools

This modernization reduces risk of double registration, overlapping titles, and unauthorized occupation. However, only Chanote titles are currently fully compatible with these systems.

X. Conclusion

Land measurement in Thailand is a highly formalized process rooted in traditional Thai units and modernized through GPS surveying and digital registries. Legal ownership, transaction validity, and dispute resolution all depend on accurate land area definitions and reliable title surveys.

Understanding the hierarchy of title deeds, surveying procedures, and measurement units is essential for professionals engaged in land acquisition, leasing, development, or litigation. Errors in measurement or failure to verify boundary data can result in substantial legal and financial exposure.