REPORT ON THE CURRENT STATUS OF
UNITED NATIONS ROMANIZATION SYSTEMS FOR GEOGRAPHICAL NAMES
Compiled by the UNGEGN Working Group on Romanization Systems
Version 2.2c, May 2004

Thai

The United Nations recommended system was first approved in 1967 (resolution I/14), based on the modified general system of the Royal Institute of Thailand. The table and notes on its application were published in vol. II of the conference reports (United Nations Conference on the Standardization of Geographical Names. Geneva, 4-22 September 1967. Vol. II. Proceedings of the Conference and technical papers, pp. 122-123). A revised version of the system was officially endorsed by the government of Thailand in 2000. This was approved at the Eighth United Nations Conference for the Standardization of Geographical Names in Berlin, 2002, based on a document submitted by Thailand (Principles of Romanization for Thai Script by Transcription Method. Eighth United Nations Conference on the Standardization of Geographical Names. Berlin, 27 August – 5 September 2002. Document E/CONF.94/INF.41).

Thai uses an alphasyllabic script. In Thai writing word division is not ordinarily indicated which may complicate the romanization. The romanization system is not reversible to its original script form.

Romanization

Thai characters are romanized in two ways depending on whether they denote syllable-initials or syllable-finals. The romanization of syllable-finals is indicated in parentheses.

1 ก k (k)
2 ข kh (k)
3 ฃ kh (k)
4 ค kh (k)
5 ฅ kh (k)
6 ฆ kh (k)
7 ง ng (ng)
8 จ ch (t)
9 ฉ ch (t)
10 ช ch (t)
11 ซ s (t)
12 ฌ ch (t)
13 ญ y (n)
14 ฎ d (t)
15 ฏ t (t)
16 ฐ th (t)
17 ฑ th,d (t)
18 ฒ th (t)
19 ณ n (n)
20 ด d (t)
21 ต t (t)
22 ถ th (t)
23 ท th (t)A
24 ธ th (t)
25 น n (n)
26 บ b (p)
27 ป p (p)
28 ผ ph (p)
29 ฝ f (p)
30 พ ph (p)
31 ฟ f (p)
32 ภ ph (p)
33 ม m (m)
34 ย y
35 ร r (n)
36 ล l (n)
37 ว w
38 ศ s (t)
39 ษ s (t)
40 ส s (t)
41 ห h
42 ฬ l (n)
43 อ oB
44 ฮ h

Vocalic nuclei and special characters (ก stands for any consonant character)

1 กะ a
2 กัก a
3 กรรก a
4 กา a
5 กรร an
6 กำ am
7 กิ i
8 กี i
9 กึ ue
10 กื ue
11 กือ ue
12 กุ u
13 กู u
14 เกะ e
15 เก็ก e
16 เก e
17 แกะ ae
18 แก็ก ae
19 แก ae
20 โกะ o
21 ก o
22 โก o
23 เกาะ o
24 กอ o
25 เกอะ oe
26 เกิก oe
27 เกอ oe
28 เกียะ ia
29 เกีย ia
30 เกือะ uea
31 เกือ uea
32 กัวะ ua
33 กัว ua
34 กวก ua
35 ใก ai
36 ไก ai
37 กัย ai
38 ไกย ai
39 กาย ai
40 เกา ao
41 กาว ao
42 กุย ui
43 โกย oi
44 กอย oi
45 เกย oei
46 เกือย ueai
47 กวย uai
48 กิว io
49 เก็ว eo
50 เกว eo
51 แก็ว aeo
52 แกว aeo
53 เกียว iao
54 ฤ rueA
55 ฤๅ rue
56 ฦ lue
57 ฦๅ lue

Notes (Notes 1-5 have been adapted from Principles of Romanization for Thai Script by Transcription Method. Eighth United Nations Conference on the Standardization of Geographical Names. Berlin, 27 August – 5 September 2002. Document E/CONF.94/INF.41.)

  1. In multi-syllable words, the final character of the preceding syllable and the initial character of the succeeding syllable may cause reading ambiguity. Therefore hyphen is used for syllable separation according to the following rules:
    1. Hyphen is inserted when the final character of the preceding syllable is a vowel and the initial character of the succeeding syllable is ng (ง), e.g.สง่า Sa-nga.
    2. Hyphen is inserted when the final character of the preceding syllable is ng (ง) and the initial character of the succeeding syllable is a vowel, e.g.บังอร Bang-on.
    3. Hyphen is inserted when the initial character of the succeeding syllable is a vowel, e.g. สะอาด sa-at, สำอาง sam-ang.
  2. A word followed by maiyamok (ๆ) is written twice according to the reading rules, e.g. ทำบ่อย ๆ tham boi boi, ไฟไหม้ ๆ fai mai fai mai.
  3. Words followed by paiyannoi (ฯ), which shortens forms of a well known word or words, are written in full according to the reading rules, e.g. กรุงเทพฯ Krung Thep Maha Nakhon, โปรดเกล้าฯ protklao protkramom.
  4. An initial อ as a vowel-bearer which is phonetically a glottal stop [ʔ] is ignored.
  5. One must bear in mind that the romanization of Thai in this case employs the transcription method. Thus, tone marks (·่, ·้, ·๊ and ·๋) and diacritical marks including the silencing mark (·์) and the vowel shortening mark (·็), are completely ignored. In order to transcribe Thai words correctly one must know how to read and pronounce them. There are many words that carry a character or characters that are not pronounced, such as สามารถ samat (ร is silent), พรหม Phrom (ห is silent), ลักษณม์ lak (ษณม์ are silent), ธาตุ that (·ุ is silent), อินทรธนู inthanu (ทร are silent), and there are also a number of words in Thai where a syllable with an intruding vowel [a] must be inserted such as ปรารถนา pratthana (ร is silent and [tha] is inserted), and รัตนา rattana ([ta] is inserted) when pronouncing them.
  6. When using geographical names romanized according to the previous 1967 version of the official Thai romanization system, it is essential to know that earlier no distinction was made between the vowels u and ue (u was used in both cases, this applied to characters 9, 10, 11, 30, 31, 46, 54, 55, 56 and 57 in the table for vocalic nuclei and special characters) and some diphthongs were romanized differently (iu for character 48 /now io/, ieo for character 53 /now iao/ in the table mentioned).

Other systems of romanization

The transliteration of Thai in the standard ISO 11940:1998 (This is a modification of a document presented in 1992: Romanized Transliteration of Thai. Sixth United Nations Conference on the Standardization of Geographical Names. Vol. II. Technical papers. New York, 25 August - 3 September 1992, pp. 369-379. Some consonants have been given revised equivalents in the ISO standard) gives each Thai character a unique equivalent in the Roman script (a single letter or a combination of a letter plus a "modifier letter"). The Thai characters are transliterated strictly in the order they are written, diacritical marks accompanying a consonant are transliterated starting by the uppermost mark and finishing with the subscript mark. As an example, here are some transliteration equivalents: ก k, ข k̄h, ฃ ḳ̄h, ค kh, ฅ k’h, ฆ ḳh, ง ng; ะ a, ั ạ, า ā, ำ å, เ e, แ æ, etc.