The Thai alphabet has 44 consonants, each named after a word that begins with it — ko kai is "k as in kai (chicken)" — and each belonging to one of three classes (mid, high, low) that decide a syllable's tone. The charts below give every consonant with its name, class, romanization, and closest English sound, followed by the main vowel signs.
Dictionary order. Each name pairs the letter's sound with its mnemonic word — Thai schoolchildren recite the whole list: ko kai (chicken), kho khai (egg), and so on. The class column is the key to the writing system: mid (9 letters), high (11), and low (24) classes determine which tone a syllable carries. Two letters, ฃ and ฅ, are obsolete — modern spelling uses ข and ค instead.
| Letter | Name | Class | Romanization | Sounds like |
|---|---|---|---|---|
| ก | ko kai (chicken) | Mid | k | unaspirated k — between g in "go" and k in "ski" |
| ข | kho khai (egg) | High | kh | k in "kit", with a puff of air |
| ฃ | kho khuat (bottle) — obsolete | High | kh | same as ข; no longer used in spelling |
| ค | kho khwai (buffalo) | Low | kh | k in "kit", with a puff of air |
| ฅ | kho khon (person) — obsolete | Low | kh | same as ค; no longer used in spelling |
| ฆ | kho rakhang (bell) | Low | kh | k in "kit"; rare, mostly Pali-Sanskrit loans |
| ง | ngo ngu (snake) | Low | ng | ng in "singer" — even at the start of a word |
| จ | cho chan (plate) | Mid | ch | ch in "church", but crisp, with no puff |
| ฉ | cho ching (cymbals) | High | ch | ch in "church", with a puff |
| ช | cho chang (elephant) | Low | ch | ch in "church", with a puff |
| ซ | so so (chain) | Low | s | s in "sun" |
| ฌ | cho choe (bush) | Low | ch | like ช; very rare |
| ญ | yo ying (woman) | Low | y | y in "yes" (an n sound when it ends a syllable) |
| ฎ | do chada (headdress) | Mid | d | d in "door" |
| ฏ | to patak (goad) | Mid | t | unaspirated t, as in "stop" |
| ฐ | tho than (pedestal) | High | th | t in "top", with a puff |
| ฑ | tho montho (Montho, a queen) | Low | th | t in "top"; rare |
| ฒ | tho phu thao (elder) | Low | th | t in "top"; rare |
| ณ | no nen (novice monk) | Low | n | n in "note" |
| ด | do dek (child) | Mid | d | d in "door" |
| ต | to tao (turtle) | Mid | t | unaspirated t, as in "stop" — often heard as a soft d |
| ถ | tho thung (sack) | High | th | t in "top", with a puff |
| ท | tho thahan (soldier) | Low | th | t in "top", with a puff |
| ธ | tho thong (flag) | Low | th | t in "top"; mostly in loanwords |
| น | no nu (mouse) | Low | n | n in "note" |
| บ | bo baimai (leaf) | Mid | b | b in "book" |
| ป | po pla (fish) | Mid | p | unaspirated p, as in "spin" — between b and p |
| ผ | pho phueng (bee) | High | ph | p in "pin", with a puff — never an f |
| ฝ | fo fa (lid) | High | f | f in "fun" |
| พ | pho phan (tray) | Low | ph | p in "pin", with a puff |
| ฟ | fo fan (teeth) | Low | f | f in "fun" |
| ภ | pho samphao (junk boat) | Low | ph | p in "pin"; mostly in loanwords |
| ม | mo ma (horse) | Low | m | m in "map" |
| ย | yo yak (giant) | Low | y | y in "yes" |
| ร | ro ruea (boat) | Low | r | rolled or flapped r; relaxes to l in casual speech |
| ล | lo ling (monkey) | Low | l | l in "lamp" |
| ว | wo waen (ring) | Low | w | w in "wet" |
| ศ | so sala (pavilion) | High | s | s in "sun"; in Sanskrit loans |
| ษ | so ruesi (hermit) | High | s | s in "sun"; in Sanskrit loans |
| ส | so suea (tiger) | High | s | s in "sun" |
| ห | ho hip (chest) | High | h | h in "hat"; also silent before low-class letters to change their tone |
| ฬ | lo chula (kite) | Low | l | l in "lamp"; rare |
| อ | o ang (basin) | Mid | — | silent vowel carrier — holds a vowel with no consonant sound |
| ฮ | ho nokhuk (owl) | Low | h | h in "hat" |
Thai vowels are written around the consonant — after it (า), above it (ิ), below it (ุ), or before it (เ, แ, โ, ใ, ไ). The marks written above or below are combining signs: they look detached on their own here, but attach automatically when written after a consonant, e.g. ก + ั = กั. Most vowels come in short/long pairs that differ only in length.
| Vowel | Name | Romanization | Sounds like |
|---|---|---|---|
| ะ | sara a | a | u in "cut" — short |
| ั | mai han akat | a | u in "cut", written above the consonant |
| า | sara aa | aa | a in "father" — long |
| ำ | sara am | am | um in "drum" |
| ิ | sara i | i | i in "tip" — short |
| ี | sara ii | ii | ee in "see" — long |
| ึ | sara ue | ue | say "oo" while smiling — short |
| ื | sara uee | uee | say "oo" while smiling — long |
| ุ | sara u | u | u in "put" — short |
| ู | sara uu | uu | oo in "boot" — long |
| เ | sara e | e | a in "gate"; written before the consonant |
| แ | sara ae | ae | a in "cat"; written before the consonant |
| โ | sara o | o | o in "go"; written before the consonant |
| ใ | sara ai mai muan | ai | i in "hi"; used in only 20 words |
| ไ | sara ai mai malai | ai | i in "hi"; the everyday ai |
Thai has five tones — mid, low, falling, high, rising — and the script encodes them through a three-way interaction: the class of the initial consonant (mid, high, or low), the tone mark above it (if any), and whether the syllable is "live" (ending in a long vowel or a nasal) or "dead" (ending in a short vowel or a stop). A plain live syllable is mid tone after a mid- or low-class letter but rising after a high-class one; add the same mark mai ek (่) and a mid-class บ่า comes out low tone while low-class ม่า comes out falling. Learners memorize this as a small grid, not case by case.
This is why Thai keeps several letters for one sound. Five letters say kh and six say th not by accident but by design: ข (high class) and ค (low class) are identical as consonants, yet they impose different tones on the syllables they begin. The duplicates preserve the tone system — and the etymology of Pali and Sanskrit loanwords, which is why rare letters like ฆ, ฌ, and ฑ survive mainly in religious and royal vocabulary. Silent ห before a low-class letter is another tone tool: it lends its high class to the syllable, as in หมา (mǎa, dog).
Two more contrasts complete the sound system. Aspiration is phonemic: unaspirated ป and ต (no puff of air — English speakers often hear b and d) are different letters and different words from aspirated พ and ท. And endings are restricted: only -p, -t, -k, -m, -n, -ng, -w, and -y can close a syllable, so letters shift value at the end of one — ล (l) is pronounced n there, and ส (s) becomes t, which is why สวัสดี is said sa-wat-dee despite the common spelling "sawasdee".
The Thai script is traditionally credited to King Ramkhamhaeng the Great of Sukhothai, who adapted it from Old Khmer around 1283. The Ram Khamhaeng inscription, a stone pillar describing his kingdom, is the oldest surviving text in the script — and since Khmer descends from the Pallava script of South India, Thai is a distant grandchild of ancient Brahmi and a cousin of Devanagari.
Thai was among the first scripts anywhere to write tone systematically: the Sukhothai-era system already used two tone marks, and the modern script uses four. The language later went through a great tone shift while the spelling stood still, so today's rules — class plus mark plus syllable type — read like a fossil record of 13th-century pronunciation, which is precisely why the consonant classes must be learned rather than heard.
The alphabet officially retains 44 consonants, but two dropped out of use in the early 20th century: ฃ (kho khuat) and ฅ (kho khon) were left off early Thai typewriters to save keys, and modern spelling replaced them with ข and ค. Thai also writes no spaces between words — spaces mark the ends of phrases instead — and has no capital letters.
44 consonants, of which 42 are used in modern spelling (ฃ and ฅ are obsolete), plus around 15 basic vowel symbols that combine into roughly 32 vowel forms, and 4 tone marks. Thai dictionaries sort words by the 44 consonants, so the consonant chart is the alphabet Thai children learn first.
They set the tone of the syllable. The same written tone mark produces different tones depending on whether the initial consonant is mid, high, or low class — and an unmarked syllable gets its tone from class plus syllable shape alone. That is also why Thai has duplicate letters for one sound: ข (high) and ค (low) sound identical but give their syllables different tones.
Each name pairs the letter's sound with a mnemonic word: ko kai is "k as in kai (chicken)", mo ma is "m as in ma (horse)". Since many letters share a sound — six letters say th — the word tells you exactly which letter is meant, the way English speakers say "B as in bravo". Thai children learn the full 44-name chant in school.
Thai and Lao are sister scripts — Lao looks like a rounded, simplified Thai with only 27 consonants, and a Thai reader can partly decipher it. Khmer is the parent: Thai was adapted from Old Khmer in the 13th century, and all three descend from India's Brahmi script via Pallava. Despite the geography, Thai has no connection to Chinese characters — it is fully phonetic.
No — each letter has a single form, and there are no capitals to mark sentences or names. Thai also writes no spaces between words; spaces separate phrases and sentences instead. What learners gain in skipping case, they spend on tones: reading a syllable correctly means combining its consonant class, tone mark, and vowel length.