The Thai script, explained

The script at a glance

A consonant with a vowel built in

Every Thai consonant letter has a vowel sound of its own. Write a vowel sign next to it to change that sound, or leave the sign out and the built-in one is read. That's what makes the script an abugida.

Three classes of consonant

The 44 consonant letters fall into three classes: mid, high and low. The class of the consonant that starts a syllable is the first thing the tone rules ask about. The mid class is the smallest, with 9 letters.

The lighter letters are obsolete or rare.

The Thai alphabet chart has every letter with its name, its sound and audio, and each class has a page of its own: mid-class consonants, high-class consonants and low-class consonants. For the reasoning behind the classes, read Thai consonant classes explained.

Several letters share one sound

The 44 consonant letters stand for 21 different sounds at the start of a syllable, so many letters share a sound. The sound th has six letters and the sound kh has five letters. Letters that share a sound can sit in different classes, and the class changes the tone of the syllable.

Each letter says its class under it. The lighter letters are obsolete or rare.

Vowels written around the consonant

Thai has 24 vowel forms in 12 pairs, one short and one long. A vowel takes one of five places next to its consonant: before it, after it, above it, below it, or wrapped around it.

Short and long vowels sound alike to an English ear, yet length decides whether a dead syllable counts as short or long. For low-class consonants that changes the tone. Eight forms also change shape when a final consonant closes the syllable, so the vowel you learned isn't always the one you see. The Thai vowels chart shows every pair with audio.

The tone comes from the spelling

Thai has five tones: mid, low, falling, high and rising. Three things in the spelling decide which one a word takes: the class of the first consonant, whether the syllable is live or dead, and the tone mark, if there is one.

A live syllable ends in a long vowel or a sonorant (m, n, ng, y, w), so you can hold it. A dead one ends in a short vowel or a stop (k, p, t) and cuts off.

Thai has four tone marks, all written above the first consonant. Mai ek (◌่) and mai tho (◌้) are the common pair. Mai trii (◌๊) and mai jat-ta-waa (◌๋) are rare.

กา, ขา and ค่า end in the same vowel, and the tone changes with the consonant and the mark.

• กาHear it

  gaa, "crow"

  The ก is mid class, the syllable is live and there's no tone mark, so the tone is mid.

• ขาHear it

  khaa, "leg"

  The ข is high class, the syllable is live and there's no tone mark, so the tone is rising.

• ค่าHear it

  khaa, "value, cost"

  The ค is low class and the mai ek (◌่) on top gives a falling tone.

The Thai tone rules chart has the whole table with a real word in every cell, and the Thai tone rules practice gives you new syllables to work out.

Words run together

Thai has no spaces between words and no capital letters. A space usually marks the end of a phrase or a sentence, so you find the word boundaries yourself as you read. The Thai reading practice page has 16 real signs and menus to decode, each spoken aloud.

Why romanisation isn't enough

Romanised Thai has no single standard. The official system is the one on Thai road signs, and it leaves out the tone and the vowel length. Phrasebooks and courses often use systems of their own, and names are romanised in different ways from one place to the next. The Thai spelling is the same everywhere, and it shows the vowel length and, for almost every syllable, the tone.

Source: Romanization of Thai, Wikipedia.

Reading a syllable, step by step

1. Find the consonant that starts the syllable and note its class.
2. Read the vowel and note whether it's short or long.
3. See how the syllable ends. With the vowel length, that tells you whether it's live or dead.
4. Look for a tone mark.
5. Put the class, the syllable type and the mark into the tone chart.

A few common words are spelt one way and said another, so the steps work for almost every syllable and not for every one.

The script's origin

The Thai script descends from the Old Khmer script, which goes back to the Pallava script of southern India. Thai tradition credits King Ramkhamhaeng with creating it in the late 13th century. Scholars have challenged that account.

Sources: Thai script, Wikipedia; Thai script notes, Richard Ishida for the W3C.

Where to start

1. Learn the mid-class consonants first.
2. Take lesson 1, which is free and has audio and a quiz.
3. Learn the rules on the tone chart and try them in the tone drill.
4. Read a real sign on the reading page.