{"id":279,"date":"2023-06-17T13:41:12","date_gmt":"2023-06-17T06:41:12","guid":{"rendered":"https:\/\/www.thailawonline.com\/measurements-in-thailand\/"},"modified":"2026-09-05T19:48:30","modified_gmt":"2026-09-05T12:48:30","slug":"measurements-in-thailand","status":"publish","type":"page","link":"https:\/\/www.thailawonline.com\/fr\/measurements-in-thailand\/","title":{"rendered":"Mesures en Tha\u00eflande"},"content":{"rendered":"\n

Thailand adopted the metric system by the Weights and Measures Act of B.E. 2466 (1923). That Act is no longer the law.<\/strong> It was repealed, along with its 1933 and 1934 amendments, Revolutionary Council Announcement No. 171 of 1972 and the Act (No. 4) of B.E. 2526, by section 3 of the Weights and Measures Act B.E. 2542 (1999)<\/strong>, which is the instrument in force today.<\/p>\n\n\n\n

\ud83d\udd34 And the traditional Thai units are not folklore. They are lawful units of measurement.<\/strong> Section 9<\/strong> of the 2542 Act provides that all weighing, measuring of capacity and measuring shall use the weights and measures of the metric system, or of the traditional system referred to the metric system as prescribed in the schedule annexed to this Act<\/em>. So rai, ngan and square wah<\/a> are not a rural survival that the law tolerates: they are defined in the Act’s own schedule, which is exactly why they appear on a Chanote<\/a> and in the Land Department<\/a>‘s own records. Section 10<\/strong> lets the Minister, on the Committee’s advice, require the metric system alone for buying and selling in a given locality, so the position can be narrowed by announcement; but absent such an announcement a price quoted per square wah is quoted in a statutory unit.<\/p>\n\n\n\n

Here are the conversions, with the statutory list separated from the customary units that guides usually print beside it:<\/p>\n\n\n\n

Thai unit<\/th>Metric<\/th>Where the figure comes from<\/th><\/tr><\/thead>
1 square wah (\u0e15\u0e32\u0e23\u0e32\u0e07\u0e27\u0e32<\/em>, \u0e27\u0e52)<\/td>4 square metres<\/td>Schedule, part B(2)<\/td><\/tr>
1 ngan (\u0e07\u0e32\u0e19<\/em>, \u0e07.) = 100 square wah<\/td>400 square metres<\/td>Schedule, part B(2)<\/td><\/tr>
1 rai (\u0e44\u0e23\u0e48<\/em>, \u0e23.) = 4 ngan = 1 square sen<\/td>1,600 square metres<\/td>Schedule, part B(2)<\/td><\/tr>
1 khuep (\u0e04\u0e37\u0e1a<\/em>, \u0e04.)<\/td>one quarter of a metre, 25 cm<\/td>Schedule, part B(1)<\/td><\/tr>
1 sok (\u0e28\u0e2d\u0e01<\/em>, \u0e28.) = 2 khuep<\/td>one half of a metre, 50 cm<\/td>Schedule, part B(1)<\/td><\/tr>
1 wa (\u0e27\u0e32<\/em>, \u0e27.) = 4 sok<\/td>2 metres<\/td>Schedule, part B(1)<\/td><\/tr>
1 sen (\u0e40\u0e2a\u0e49\u0e19<\/em>, \u0e2a.) = 20 wa<\/td>40 metres<\/td>Schedule, part B(1)<\/td><\/tr>
1 kwian luang (\u0e40\u0e01\u0e27\u0e35\u0e22\u0e19\u0e2b\u0e25\u0e27\u0e07<\/em>, \u0e01\u0e27.)<\/td>2,000 litres<\/td>Schedule, part B(3)<\/td><\/tr>
1 ban luang (\u0e1a\u0e31\u0e49\u0e19\u0e2b\u0e25\u0e27\u0e07<\/em>, \u0e1a.) = half a kwian<\/td>1,000 litres<\/td>Schedule, part B(3)<\/td><\/tr>
1 sat luang (\u0e2a\u0e31\u0e14\u0e2b\u0e25\u0e27\u0e07<\/em>, \u0e2a.) = one fiftieth of a ban<\/td>20 litres<\/td>Schedule, part B(3)<\/td><\/tr>
1 thanan luang (\u0e17\u0e30\u0e19\u0e32\u0e19\u0e2b\u0e25\u0e27\u0e07<\/em>, \u0e17.) = one twentieth of a sat<\/td>1 litre<\/td>Schedule, part B(3)<\/td><\/tr>
1 hap luang (\u0e2b\u0e32\u0e1a\u0e2b\u0e25\u0e27\u0e07<\/em>, \u0e2b.)<\/td>60 kilograms<\/td>Schedule, part B(4)<\/td><\/tr>
1 chang luang (\u0e0a\u0e31\u0e48\u0e07\u0e2b\u0e25\u0e27\u0e07<\/em>, \u0e0a.) = one hundredth of a hap<\/td>600 grams<\/td>Schedule, part B(4)<\/td><\/tr>
1 karat luang (\u0e01\u0e30\u0e23\u0e31\u0e15\u0e2b\u0e25\u0e27\u0e07<\/em>, \u0e01\u0e23.), gemstones only<\/td>1 metric carat, 20 centigrams<\/td>Schedule, part B(4)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Those fourteen are the whole of the statutory list<\/strong>, and the third column says so on purpose: they are copied from the schedule at the end of the Weights and Measures Act B.E. 2542 (1999)<\/strong>, part B, traditional weights and measures referred to the metric system<\/em>. Anything else you meet is custom or trade practice rather than a legal unit, and the common ones are worth naming because guides print them beside the statutory figures as though they were the same thing:<\/p>\n\n\n\n

Customary unit<\/th>Usual value<\/th>Status<\/th><\/tr><\/thead>
1 niu (\u0e19\u0e34\u0e49\u0e27<\/em>), a finger-width<\/td>about 2.08 cm, being one twelfth of a khuep<\/td>Not in the schedule. 12 niu make the 25 cm khuep, so 2 cm flat does not add up<\/td><\/tr>
1 yot (\u0e42\u0e22\u0e0a\u0e19\u0e4c<\/em>) = 400 sen<\/td>16 km<\/td>Not in the schedule; it follows from the sen<\/td><\/tr>
1 baht of gold ornament (\u0e17\u0e2d\u0e07\u0e23\u0e39\u0e1b\u0e1e\u0e23\u0e23\u0e13<\/em>)<\/td>about 15.16 grams<\/td>Gold trade standard, not a statutory unit<\/td><\/tr>
1 baht of gold bar (\u0e17\u0e2d\u0e07\u0e04\u0e33\u0e41\u0e17\u0e48\u0e07<\/em>)<\/td>about 15.244 grams<\/td>Gold trade standard, and it is not the same figure as the ornament baht<\/td><\/tr>
1 tamlung (\u0e15\u0e33\u0e25\u0e36\u0e07<\/em>) = 4 baht<\/td>about 60 grams<\/td>Customary, not in the schedule<\/td><\/tr>
1 chang, customary (\u0e0a\u0e31\u0e48\u0e07<\/em>) = 20 tamlung<\/td>about 1.2 kg<\/td>\u26a0\ufe0f Customary. The statutory<\/strong> chang luang is 600 grams<\/strong>, half this, which is why the schedule puts 100 chang in a hap and the customary ladder puts 50<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Table of Contents<\/h2>