Vowels Written Before Their Consonant

Foundations

The written signs เ, แ, โ, ใ, and ไ appear to the left of their syllable’s onset consonant or cluster. The onset is pronounced before the vowel sound. These are five written signs, not the complete list of Thai vowel sounds; signs such as เ also participate in multi-part vowel spellings.

How It Works

Thai vowel spellings use signs around the onset consonant. The five signs เ, แ, โ, ใ, and ไ are written before the onset of the syllable to which they belong.

Basic Written Forms:

  • เ-: The basic long vowel /eː/.
  • แ-: The basic long vowel /ɛː/.
  • โ-: The basic long vowel /oː/.
  • ใ- (sara mai muan) and ไ- (sara mai malai): Both commonly represent /aj/. The traditional list for ใ contains 20 base words; compounds and other forms built from those words can also contain ใ.

These signs can also form parts of other vowel spellings, so a sign alone does not always tell you the whole vowel. English words such as “hey” and “go” vary by accent and often have a glide; do not treat them as exact models of Thai /eː/ and /oː/.

Other /aj/ Spellings:
ไ is used in many words, but it does not cover every other /aj/ spelling. Forms with อัย and ไอย also occur. Keep อาย /aːj/ distinct because its vowel is long.

Reading and Placement:

  • Reading order: In ไป /paj/, say /p/ before /aj/, even though ไ is written first. This concerns the onset of this syllable, not every earlier consonant in a multi-syllable word.
  • True consonant clusters: In เพลง, เ is written before the whole onset cluster พล. In ขโมย, ข belongs to an earlier syllable with an unwritten vowel, and โ belongs with the later onset ม.
  • Tone marks: A tone mark is anchored to a consonant, not to a preposed vowel sign. In a true onset cluster such as ใกล้, it is anchored to the second consonant. Two consonants in different syllables are not one onset cluster.

For other vowel spellings and vowel length, see Vowels Sit All Around The Consonant and Short And Long Vowels.

Examples (5)

  1. ไป

    Go

    Word by Word: Written sign order: ai + p.

    Uses the leading vowel ไ (sara mai malai). Notice the vowel is written first, but the 'p' sound (ป) is pronounced first.

  2. แม่

    Mother

    Word by Word: Written sign order: ae + m + (tone).

    Uses the leading vowel แ (sara ae). The tone mark sits above the consonant ม, not the vowel.

  3. ดีใจ

    Happy

    Word by Word: Written sign order: d + ee + ai + ch. Spoken pronunciation: /diː caj/.

    The second syllable uses ใ (sara mai muan), one of the two 'ai' leading vowels.

  4. เพลง

    Song

    Word by Word: Written sign order: e + ph + l + ng.

    Demonstrates a consonant cluster (พล). The leading vowel เ stays at the very front of the word.

  5. แตงโม

    Watermelon

    Word by Word: Written sign order: ae + t + ng + o + m.

    Both syllables in this word start with leading vowels (แ and โ).

Common Mistakes

  • Placing tone marks on the leading vowel.

    ไ่ม่
    ไม่

    Tone marks must always be placed above the consonant, never above leading vowels like ไ.

  • Placing the tone mark on the first consonant in a cluster.

    เป่ลี่ยน
    เปลี่ยน

    In a true onset cluster such as ปล in เปลี่ยน, the tone mark is anchored to the second consonant, ล. This is a spelling rule for an onset cluster, not for any two consonants in different syllables.

  • Splitting a consonant cluster with the vowel.

    พเลง
    เพลง

    For a true onset cluster such as พล in เพลง, the preposed vowel sign is written before the whole cluster. Do not split that cluster as พเลง. A word with an earlier separate syllable, such as ขโมย, follows the placement for each syllable instead.