Which system should I use
Learning to readPaiboon+sà-wàt-diiDay-to-day reading and dictionary work. Tones marked as diacritics, vowel length doubled. Cross-references with every Paiboon Publishing book.
Official spellingRTGSsawatdiGovernment signage, maps, place names, passports. Lossy by design — no tones, no length, /c/ collapses with /cʰ/. Use when you need an official spelling.
Linguistic precisionIPAsa˨˩.wat˨˩.diː˧Phonology references, linguistic papers, anything that needs full disambiguation. Chao tone letters and length marker mean nothing is left to inference.
Academic sourcesHaas / AUAsà wàt diiOlder American textbooks (Haas, AUA, Cornell). Spaces between syllables, glottal stop on short open syllables, voiceless stops in the AUA variant.