Royal Thai General System of Transcription

The Royal Thai General System of Transcription (RTGS) is the official system for rendering Thai language words in the Latin alphabet, published by the Royal Institute of Thailand. It is used in road signs and government publications, and is the closest thing to a standard of transcription for Thai, though its use by even the government is inconsistent.. The system is almost identical to the one defined by ISO 11940-2.

Prominent features of the Royal Thai General System include:

Transcription of consonants in final position is according to pronunciation, not Thai orthography.

Vowels are transcribed in sequence as pronounced, not as in the Thai orthography. Implied vowels, which are not written in Thai orthography, are inserted as pronounced.

A hyphen is used to avoid ambiguity in syllable separation: before a succeeding syllable that starts with a vowel and before ⟨ng⟩ when the preceding syllable ends with a vowel.

Transcribed words are written with spaces between them, although there are no spaces when written in Thai letters. For example, "สถาบันไทยคดีศึกษา" (meaning "Institute of Thai Studies") is transcribed as "Sathaban Thai Khadi Sueksa". However, compounds and names of persons are written without spaces between words. For example, "ลูกเสือ" (from "ลูก" + "เสือ"; meaning "scout") is transcribed as "luksuea", not "luk suea", and "โชคชัย จิตงาม" (the first and last names of a person) is transcribed as "Chokchai Chitngam", not "Chok Chai Chit Ngam".

The Royal Thai General System does not transcribe all features of Thai phonology. Particularly it has the following shortcomings:

The original design envisioned that the general system would give broad details of pronunciation, while the precise system would supplement this with information as to vowel lengths, tones, and Thai characters used. The ambiguity of ⟨ch⟩ and ⟨o⟩ was introduced in the 1968 version.

For consonants, the transcription is different depending on the location in the syllable. In the section on vowels a dash ("–") indicates the relative position of the initial consonant belonging to the vowel.

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