Thai Romanization Table

There are many systems in use for the Romanization of Thai. Some place more emphasis on the etymology of a word, others on the pronunciation. This table compares three standards; ISO 11940, the Royal Thai General System of Transcription (RTGS), and the American Library Association - Library of Congress (ALA-LC) standard. ISO 11940 and the ALA-LC standard are transliteration systems, the RTGS is technically a transcription system (see Transliteration vs. Transcription for a discussion of the differences). In practice, these standards are applied inconsistently, or a combination of them will be used in a single document or on a single sign.

The RTGS and the ALA-LC transcribe consonants differently depending on whether they are at the beginning or the end of a syllable. In the table, both Latin equivalents are given, separated by a slash / .

Consonants

Thai	ISO 11940	RTGS	ALA-LC
ก	k	k / k	k / k
ข	k̄h	kh / k	kh / k
ฃ	ḳ̄h	kh / k	kh / k
ค	kh	kh / k	kh / k
ฅ	k̛h	kh / k	kh / k
ฆ	ḳh	kh / k	kh / k
ง	ng	ng / ng	ng / ng
จ	c	ch / t	čh / t
ฉ	c̄h	ch / -	ch / t
ช	ch	ch / t	ch / t
ซ	s	s / t	s / t
ฌ	c̣h	ch / -	ch / t
ญ	ỵ	y / n	y / n
ฎ	ḍ	d / t	d / t
ฏ	ṭ	t / t	t / t
ฐ	ṭ̄h	th / t	th / t
ฑ	ṯh	th / t	th, d / t
ฒ	t̛h	th / t	th / t
ณ	ṇ	n / n	n / n
ด	d	d / t	d / t
ต	t	t / t	t / t
ถ	t̄h	th / t	th / t
ท	th	th / t	th / t
ธ	ṭh	th / t
น	n	n / n	n / n
บ	b	b / b	b / p
ป	p	p / p	p / p
ผ	p̄h	ph / -	ph / p
ฝ	f̄	f / -	f / p
พ	pj	ph / p	ph / p
ฟ	f	f \ p	f / p
ภ	p̣h	ph / p	ph / p
ม	m	m / m	m / m
ย	y	y / -	y / -
ร	r	r / n	r / n1
ฤ	v	rue, ri, roe / -	rư, ri, rœ / -
ล	l	l / n	l / n
ฦ	ł	lue	lu
ว	w	w	w / -
ศ	ṣ̄	s / t	h / -
ษ	s̛̄	s / t	s / t
ส	s̄	s / t	s / t
ห	h̄	h / -
ฬ	ḷ	l / n	l / n
อ	x	o	’ (ayn) / - 2
ฮ	ḥ	h / -	h / -

Vowels and Punctuation

Thai	ISO 11940	RTGS	ALA-LC
ะ	a	a	a
◌ั	ạ	a	a
า	ā	a	ā
ำ	å	am	am
◌ิ	i	i	i
◌ี	ī	i	ī
◌ึ	ụ	ue	ư
◌ื	ụ̄	ue	ư̄
◌ุ	u	u	u
◌ู	ū	u	ū
เ	e	3 (see below)	̄e
แ	æ	3 (see below)	ǣ
โ	o	3 (see below)	ō
ใ	ı	ai	ai
ไ	ị	3 (see below)	ai
ฤๅ	vɨ		rư̄, lư̄
ฯ	ǂ
ๆ	«
◌็	̆
◌่	̀
◌้	̂
◌๊	́

Vowels (contextual)

Thai	RTGS	ALA-LC
รร-	a	1
รร	an	1
เ-ะ	e	e
เ-◌็	e	e
เ-	e	̄e
แ-ะ	ae	æ
แ-	ae	ǣ
โ-ะ	o	o
โ-	o	ō
เ-ๅะ	o	ǫ
-อ	o	’ (ayn) / -2
เ-อะ	oe	œ̄
เ-◌ิ	oe	œ
เ-อ	oe	œ
เ-◌ียะ	ia	ia
เ-◌ีย	ia	īa
เ-◌ืยะ	uea	ưa
เ-◌ืย	uea	īa
-◌ัวะ	ua	ua
-◌ัว	ua	ūa
-ว-	ua	ūa
ใ-	ai	ai
ไ-	ai	ai
-◌ัย	ai	āi
ไ-ย	ai	ai
-าย	ai	āi
เ-า	ao	ao
-าว	ao	āo
-◌ุย	ui	ui
โ-ย	oi	ōi
-อย	oi	ǭi
เ-ย	oei	œ̄i
เ-◌ือย	ueai	ư̄ai
-วย	uai	ūai
-◌ิว	io	iu
เ-◌็ว	eo	eo
เ-ว	eo	eo
แ-◌็ว	aeo
แ-ว	aeo	ǣo
เ-◌ียว	iao	īeo

This article formerly appeared on ScriptSource.

Footnotes

1. When ร follows another consonant and ends a syllable, it is romanized n, and the inherent vowel of the preceding consonant is represented by ǭ (e.g., นคร nakhǭn). When รร follows another consonant and no other pronounced consonant follows in the same syllable, it is romanized an (e.g., สวรรค sawan), but if a pronounced consonant follows, it is represented by a (e.g., กรรม kam). ↩ ↩² ↩³

2. In four common words อ occurs preceding another consonant to mark a certain tone and is then not romanized. ↩ ↩²

3. The RTGS and ALA-LC transcribe some vowel symbols differently depending on the context in which they appear, as follows. (In this chart, the hyphen symbol - represents a consonant.) ↩ ↩² ↩³ ↩⁴