Thai Vowels — Complete Guide
Thai vowels come in short and long versions — and the length changes the meaning. This guide covers all vowel symbols with RTGS romanization and English pronunciation comparisons.
Thai distinguishes short (brief) and long (prolonged) vowels. This distinction is phonemic: อะ (short a) and อา (long aa) are different sounds that produce different words — like English "bit" vs "beat", but more systematically.
Thai vowel symbols are unique: they can appear before, after, above, or below the consonant depending on which vowel it is. This positional variation is one of the quirks of the Thai script. The interactive app at DecrypThai shows each vowel in real words with audio.
Thai also has diphthongs (compound vowels) that combine two vowel sounds into one syllable nucleus, similar to the "oi" in English "boy".
Short Vowels
| Symbol | RTGS | Pronunciation (English comparison) |
|---|---|---|
| อะ | a | a (short) — like "u" in "cut" |
| อิ | i | i (short) — like "i" in "bit" |
| อึ | ue | ue (short) — central vowel, no English equivalent; like "u" in "burn" without the r |
| อุ | u | u (short) — like "oo" in "book" |
| เอะ | e | e (short) — like "e" in "bed" |
| แอะ | ae | ae (short) — like "a" in "cat" |
| โอะ | o | o (short) — like "o" in "not" |
| เอาะ | aw | aw (short) — like "aw" in "saw" but shorter |
| ไ / ใ | ai | ai — like "i" in "kite" |
Long Vowels
| Symbol | RTGS | Pronunciation (English comparison) |
|---|---|---|
| อา | aa | aa (long) — like "a" in "father", held longer |
| อี | ii | ii (long) — like "ee" in "see" |
| อือ | ue | ue (long) — prolonged central vowel; like "ur" in "fur" without the r |
| อู | uu | uu (long) — like "oo" in "food" |
| เอ | ee | ee (long) — like "a" in "gate" |
| แอ | ae | ae (long) — like "a" in "bad", held longer |
| โอ | oo | oo (long) — like "o" in "go" |
| ออ | aw | aw (long) — like "aw" in "law" |
| เอา | ao | ao — like "ow" in "now" |
Understanding Thai Vowel Writing
Thai vowels are not always written after the consonant. Depending on the vowel, the symbol can appear before, after, above or below the consonant, and some vowels wrap around it on both sides. The five vowels เ, แ, โ, ไ and ใ are written before the consonant but pronounced after it: in เกม (geem, "game"), the เ comes first on the page, yet you say g first and the vowel second.
When a word starts with a vowel sound, Thai uses the silent consonant อ as a carrier so that the vowel has a letter to attach to. That is why you will see อ in many vowel examples.
Vowel length (short or long) is part of the spelling and it matters twice: it can change the meaning of a word, and it decides whether a syllable counts as live or dead, which affects the tone. Practice each short and long pair side by side to train your ear.
Frequently Asked Questions
How many vowels are there in Thai?
Counts vary depending on how diphthongs and special forms are treated, but you need to learn roughly 30 written vowel forms. Many of them come in short and long pairs, and they combine into a smaller number of distinct vowel sounds.
Why are some Thai vowels written before the consonant?
It is a feature of the Thai script. The vowels เ, แ, โ, ไ and ใ are written to the left of the consonant but pronounced after it. You read the syllable by finding the consonant first, then adding the vowel sound.
What is the letter อ used for in vowels?
อ acts as a silent carrier consonant when a syllable begins with a vowel sound, so there is a letter for the vowel to attach to. In other positions it can also be part of a vowel, for example in the long "aw" sound.
Does vowel length really matter?
Yes. Short and long vowels can make different words, and the length of the vowel is one of the factors that determines the tone of a syllable. Learners who ignore length are often misunderstood.
Practice Thai Vowels
The vowel quiz on DecrypThai tests you on real Thai words, with audio and instant feedback. The fastest way to internalize vowel length distinctions.
Start the Vowel Quiz →