Before 1897
Thailand has widely implemented metrological methods from time immemorial. The most common methods has been Siamese,Chinese and western. Such varied units of measurement have hindered trading developments.

1897
The King Chulalongkorn (Rama V) has expressed a desire to set up a law of metrology as a benchmark. Chaopraya Surasakmontri has come up with the idea to implement the metric system, but the idea has not been materialized.

1901
Chaophraya Dheveswongwiwat, the Minister for Agriculture, has raised a particular issue of measurement into consideration since Siam had rice as its main commodity, which has to be determined by volume measures. An act on volume measures had been drafted.

1902
The King Rama V has passed it to legal advisors for review and revision and to have the weighing and measuring instuments. Chaophraya Apairaja (Mr. Rolin Jacquemyns) and Mr. Chleser, the advisors, have drafted a Weights and Measures Act

1905
The King Rama V has been graciously pleased to establish committee to determine which one of the metrological systems should be adopted. The committee has concluded that the metric system should be adopted.

1909
In the era of the King Rama VI, Chaophraya Wongsanupraprapan, the Minister of Agriculture has approached the International Bureau of Weights and Measures to apply for a membership. Finally,

1911
The King Rama VI, has ordered the ministers of interior, finance and municipality to hold consultation on the matter. The ministers held consultations and recommended to the King that Siam should adopt the metric system.

1912
Thailand has submitted a letter of intent to the International Bureau of weights and Measures (BIPM) in France, and the country has been granted a membership

1923
The King Rama VI has been graciously pleased to enact the “Weights and Measures Act, B.E. 2466” as the country’s master law on metrological units. In the following year, the first ministerial regulation has been issued for the execution of the Act.

1995
Thailand applied to be a corresponding member of International OrganiZation of Legal Metrology (OIML)

1999
The King Bhumibol Adulyadej was graciously pleased to enact the “Weights and Measures Act, B.E. 2542”, and the Act was promulgated in the Government Gazette, Royal Decree Version, Volume 116, Part 29 a, dated 21 April 1999, that was effective since 18 October 1999.