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The Royal Thai General System of Transcription (RTGS) is the official system for rendering Thai language

Thai language

Thai , also known as Central Thai and Siamese, is the national and official language of Thailand and the native language of the Thai people, Thailand's dominant ethnic group. Thai is a member of the Tai group of the Tai–Kadai language family. Historical linguists have been unable to definitively...

 words in the Latin alphabet

Latin alphabet

The Latin alphabet, also called the Roman alphabet, is the most recognized alphabet used in the world today. It evolved from a western variety of the Greek alphabet called the Cumaean alphabet, which was adopted and modified by the Etruscans who ruled early Rome...

, 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

Transcription (linguistics)

Transcription in the linguistic sense is the systematic representation of language in written form. The source can either be utterances or preexisting text in another writing system, although some linguists only consider the former as transcription.Transcription should not be confused with...

 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
  Latin alphabet
  The Latin alphabet, also called the Roman alphabet, is the most recognized alphabet used in the world today. It evolved from a western variety of the Greek alphabet called the Cumaean alphabet, which was adopted and modified by the Etruscans who ruled early Rome...
  
  ; no diacritic
  Diacritic
  A diacritic is a glyph added to a letter, or basic glyph. The term derives from the Greek διακριτικός . Diacritic is both an adjective and a noun, whereas diacritical is only an adjective. Some diacritical marks, such as the acute and grave are often called accents...
  
  s
• spells all vowel
  Vowel
  In phonetics, a vowel is a sound in spoken language, such as English ah! or oh! , pronounced with an open vocal tract so that there is no build-up of air pressure at any point above the glottis. This contrasts with consonants, such as English sh! , where there is a constriction or closure at some...
  
  s and diphthong
  Diphthong
  A diphthong , also known as a gliding vowel, refers to two adjacent vowel sounds occurring within the same syllable. Technically, a diphthong is a vowel with two different targets: That is, the tongue moves during the pronunciation of the vowel...
  
  s using only vowel letters: ⟨a⟩, ⟨e⟩, ⟨i⟩, ⟨o⟩, ⟨u⟩
  • single letters ⟨a⟩, ⟨e⟩, ⟨i⟩, ⟨o⟩, ⟨u⟩ are simple vowels
    Monophthong
    A monophthong is a pure vowel sound, one whose articulation at both beginning and end is relatively fixed, and which does not glide up or down towards a new position of articulation....
    
     with the same value as in the International Phonetic Alphabet
    International Phonetic Alphabet
    The International Phonetic Alphabet "The acronym 'IPA' strictly refers [...] to the 'International Phonetic Association'. But it is now such a common practice to use the acronym also to refer to the alphabet itself that resistance seems pedantic...
    
     (IPA)
  • digraphs
    Digraph (orthography)
    A digraph or digram is a pair of characters used to write one phoneme or a sequence of phonemes that does not correspond to the normal values of the two characters combined...
    
     with trailing ⟨e⟩ are simple vowels, ⟨ae⟩, ⟨oe⟩, ⟨ue⟩ sound like /ɛ, ɤ, ɯ/ respectively (and are perhaps chosen for their similarity to IPA ligatures: /æ, œ, ɯ/)
  • digraphs with trailing ⟨a⟩, ⟨i⟩, ⟨o⟩ are diphthongs, indicated by /a, j, w/ respectively in IPA
• uses consonant
  Consonant
  In articulatory phonetics, a consonant is a speech sound that is articulated with complete or partial closure of the vocal tract. Examples are , pronounced with the lips; , pronounced with the front of the tongue; , pronounced with the back of the tongue; , pronounced in the throat; and ,...
  
  s as in IPA, except:
  • digraphs with ⟨h⟩ (⟨ph⟩, ⟨th⟩, ⟨kh⟩) are aspirated
    Aspiration (phonetics)
    In phonetics, aspiration is the strong burst of air that accompanies either the release or, in the case of preaspiration, the closure of some obstruents. To feel or see the difference between aspirated and unaspirated sounds, one can put a hand or a lit candle in front of one's mouth, and say pin ...
    
     /pʰ, tʰ, kʰ/ consonants, to distinguish them from the separate unaspirated ⟨p⟩, ⟨t⟩, ⟨k⟩
  • uses ⟨ng⟩ for /ŋ/, as in English
  • uses ⟨ch⟩ for /tɕʰ/ and /tɕ/, with some similarity to English
  • uses ⟨y⟩ for /j/, as in English.

Note that transcription of consonants in final position is according to pronunciation, not Thai orthography.

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 tone
  Tone (linguistics)
  Tone is the use of pitch in language to distinguish lexical or grammatical meaning—that is, to distinguish or inflect words. All verbal languages use pitch to express emotional and other paralinguistic information, and to convey emphasis, contrast, and other such features in what is called...
  
  s
• it does not differentiate between short and long vowels
  Vowel length
  In linguistics, vowel length is the perceived duration of a vowel sound. Often the chroneme, or the "longness", acts like a consonant, and may etymologically be one, such as in Australian English. While not distinctive in most dialects of English, vowel length is an important phonemic factor in...
  
  
• the notation ⟨ch⟩ does not differentiate between IPA
  International Phonetic Alphabet
  The International Phonetic Alphabet "The acronym 'IPA' strictly refers [...] to the 'International Phonetic Association'. But it is now such a common practice to use the acronym also to refer to the alphabet itself that resistance seems pedantic...
  
   /tɕ/ and IPA /tɕʰ/ (see table below)
• the notation ⟨o⟩ does not differentiate between IPA /ɔ/ and IPA /o/ (see table below)

	Phoneme 1				Phoneme 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

External links

• Discussion of romanisation (Microsoft Word document)
• Downloadable Windows-based transcription tool
• ALA-LC: PDF guide to romanization
• Thai-language.com: online transcriptions Thai-English and English-Thai