The Royal Thai General System of Transcription (RTGS) is the official system for rendering Thai language words in the Latin alphabet. 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.

Features

Prominent features of the Royal Thai General System include:

• uses only unmodified letters from the Latin alphabet; no diacritics
• spells all vowels and diphthongs using only vowel letters: a, e, i, o, u
• simple letters "a", "e", "i", "o", "u" are simple vowels, having the same value as in the International Phonetic Alphabet, IPA
• combinations with "e" second as "ae", "oe", "ue", are simple vowels, similar to respective ligatures in IPA
• combinations with trailing "a", "i", "o" (or several) are diphthongs, indicated by [a, j, w] respectively in IPA
• uses consonants as in IPA, except:
• combinations with "h" as "ph", "th", "kh" are used for aspirated p, t, k, similar to IPA , to distinguish them from the separate unaspirated "p", "t", "k"
• uses "ng" for engma as in English, IPA [ŋ]
• uses "ch" for IPA [tɕʰ] and [tɕ]
• uses "y" for IPA [j]
• note that transcription of consonants in final position is according to pronunciation, not spelling

Criticism

The Royal Thai General System has been criticized as inadequate for learners of Thai, particularly because of the following shortcomings:

• it does not record tones
• it does not differentiate between short and long vowels
• notation "ch" does not differentiate between IPA /tɕ/ and IPA /tɕʰ/ (see table below)
• notation "o" does not differentiate between IPA /ɔ/ and IPA /o/ (see table below)

	Letter 1				Letter 2
RTGS	Thai	IPA	Description	English	Thai	IPA	Description	English
ch	จ	tɕ	alveo-palatal affricate	as "ty" in "let you"	ฉ, ช, ฌ	tɕʰ	aspirated alveo- palatal affricate	as "ch" in "check"
o	โ–ะ, –	o	close-mid back short rounded	like "oa" in "boat"	เ–าะ	ɔ	open-mid back short rounded	like "aw" in "raw", but shorter
	โ–	oː	close-mid back long rounded	like "oa" in "moan"	–อ	ɔː	open-mid back long rounded	like "aw" in "raw"

Transcription table

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.

Consonants		Vowels
Letter Initial position Final position ก k k ข kh k ฃ kh k ค kh k ฅ kh k ฆ kh k ง ng ng จ ch t ฉ ch - ช ch t ซ s t ฌ ch - ญ y n ฎ d t ฏ t t ฐ th t ฑ th t ฒ th t ณ n n ด d t ต t t ถ th t ท th t ธ th t น n n บ b p ป p p ผ ph - ฝ f - พ ph p ฟ f p ภ ph p ม m m ย y - ร r n ฤ rue, ri, roe - ฤๅ rue - ล l n ฦ lue - ฦๅ lue - ว w - ศ s t ษ s t ส s t ห h - ฬ l n ฮ h -		Letter Romanisation –ะ, –ั, รร (with final), –า a รร (without final) an –ำ am –ิ, –ี i –ึ, –ื ue –ุ, –ู u เ–ะ, เ–็, เ– e แ–ะ, แ– ae โ–ะ, –, โ–, เ–าะ, –อ o เ–อะ, เ–ิ, เ–อ oe เ–ียะ, เ–ีย ia เ–ือะ, เ–ือ uea –ัวะ, –ัว, –ว– ua ใ–, ไ–, –ัย, ไ–ย, –าย ai เ–า, –าว ao –ุย ui โ–ย, –อย oi เ–ย oei เ–ือย ueai –วย uai –ิว io เ–็ว, เ–ว eo แ–็ว, แ–ว aeo เ–ียว iao

References

• PDF file setting out the system (Thai language)
• Report on the Current Status of United Nations Romanization Systems for Geographical Names: Thai

See also

• ISO 11940

External links

• Discussion of romanisation (Microsoft Word document)
• Downloadable Windows-based transcription tool
• ALA-LC: PDF guide to romanization