Thai Alphabet Table

Because the spellings are older than the sounds. Old Thai distinguished voiced, voiceless and aspirated stops - a full three-way split - and each sound got its own letter. Then the language devoiced most of its stops, collapsing /bʱ ɗʱ/ and friends onto modern /b d/ and folding several fricatives into /s/, so the letter inventory stayed 44 while the sound inventory shrank underneath it. The result is homophone letter pairs that look redundant but are not: choosing ซ or ศ or ษ for your /s/ changes the consonant class, and therefore the tone. Spelling reform has trimmed two letters (ฃ and ฅ, retired in the 1840s) but the rest survive because every one of them is load-bearing in the tone system, even when it sounds like its neighbor.

The class is the first input to the tone; the mark (or its absence) and the vowel type are the others, and Thai's five tones fall out of the combinations. Unmarked syllables: middle class gets mid tone on both live and dead vowels; high class gets rising on live vowels and low on dead ones; low class gets mid on live and high on dead. With a mark: middle class letters can take all four marks (mai ek = low, mai tho = falling, mai tri = high, mai chattawa = rising), high class letters may take only the first two (giving low and falling), and low class letters reinterpret the same two marks as high and falling. One more wrinkle: a prefixed silent ห (ho nam) or อ (o nam) makes a low-class letter behave as high class - the written consonant and the tone-rule consonant can be different letters.

ฃ (kho khuat, bottle) and ฅ (kho khon, person) are the two letters Thai retired. They once distinguished sounds that merged into /kʰ/, and after an 1840s-era printing decision reordered the alphabet around the surviving distinctions, the two lost their seats: modern Thai never writes them, dictionaries skip them, and children never learn them - though both still sit in Unicode's Thai block (U+0E03 and U+0E05), which is why they appear in font test pages and trivia quizzes more than in text. The other 42 are all in daily use; the count people usually quote, 44, includes these two museum pieces.

The Royal Thai General System (RTGS) is the government standard and what this table uses: it spells sounds unambiguously for English readers but throws away tone and vowel length - Bangkok, Ayutthaya and Phuket are all RTGS. Its quirks are visible in the table: it renders พ ภ ฟ ฝ all as ph or f, and it has no way to show that ด and ต are different letters. For pronunciation, linguists use IPA (also in the table); for learning, the honest approach is to treat RTGS as a lookup key, not a pronunciation guide - the same letters of Thai that sound alike romanize alike but behave differently in the tones.

Thai's vowels are separate marks - about 32 written forms for 21 sounds - and they attach in all four directions: เ and แ go before the consonant (เขา writes vowel-then-consonant), ิ ี ึ ื sit above, ุ ู below, and า ำ follow after, with combinations like เ-◌-า wrapping a single consonant on three sides (เขา, house of the syllable khao). This table lists only the consonants because the consonants are the part that behaves like a fixed inventory; the vowels are a positioning system. The short/long contrast they encode is not decoration either - it is the second input to every tone rule, so a learner who skips the vowel marks has skipped half the tone system.