This tool converts Devanagari Hindi into IAST, the diacritic Roman notation scholars use to represent Indic scripts precisely. Unlike loose phonetic spellings, IAST is reversible and distinguishes vowel length and retroflex consonants.
How it works
The converter normalises the input to NFC, then walks it character by character. When it hits a consonant it emits the base Roman letter and then decides the following vowel: a dependent vowel sign replaces the inherent vowel, the virama (्, U+094D) suppresses it entirely, and otherwise the inherent short a is added. Independent vowels, Devanagari digits, the anusvara (ं → ṃ), visarga (ः → ḥ) and candrabindu are mapped to their IAST equivalents. Nukta consonants such as ज़ and फ़ are handled whether typed precomposed or as base plus nukta.
IAST character mapping for common Devanagari
| Devanagari | IAST | Notes |
|---|---|---|
| अ / आ | a / ā | Short vs long a; macron marks length |
| इ / ई | i / ī | Short vs long i |
| उ / ऊ | u / ū | Short vs long u |
| क ख ग घ | k kh g gh | Velar stops |
| ट ठ ड ढ | ṭ ṭh ḍ ḍh | Retroflex stops (underdot) |
| त थ द ध | t th d dh | Dental stops |
| श ष स | ś ṣ s | Three sibilants (distinguished in IAST) |
| ञ ण न | ñ ṇ n | Three nasals |
| ं ः | ṃ ḥ | Anusvara, visarga |
| ज़ फ़ क़ | z f q | Nukta consonants for loan sounds |
Worked example
The word नमस्ते transliterates step by step:
न → na (consonant + inherent 'a')
म → ma (consonant + inherent 'a')
स् → s (virama on स suppresses the inherent 'a')
त → t (consonant — vowel sign follows)
े → e (dependent vowel sign replaces inherent 'a' on त)Result: namaste
The conjunct स्त is romanised as st (no vowel between them) because the virama
on स explicitly marks the suppression of the inherent vowel before त follows.
IAST vs other romanisation schemes
IAST is one of several schemes for Devanagari:
- IAST — scholarly, reversible, uses diacritics (ā, ṭ, ṃ). Best for academic and library contexts.
- Hunterian transliteration — used historically in official Indian gazeteers and maps. Similar but less systematic about length distinctions.
- ITRANS — ASCII-only, uses capital letters and digraphs to avoid diacritics (aa, T, N). Good for typing when diacritics are unavailable; less readable.
- ISO 15919 — a formal standard similar to IAST but with some different diacritic choices; used in libraries and ISO contexts.
- Casual phonetic spelling — everyday spellings like “Mumbai,” “Delhi,” “namaste” — convenient but not systematically reversible.
For academic publications, IAST is the expected standard. For everyday use or when you need ASCII output, ITRANS is more practical.
Reversibility
A key advantage of IAST is that it is reversible — given an IAST string you can reconstruct the Devanagari exactly, because every phonemic distinction is represented. Casual spellings are not reversible: “Delhi” could be देहली or दिल्ली depending on convention, while the IAST forms Dehlī and Dillī are unambiguous.
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