Romaji Converter — Japanese to Hepburn / Kunrei Romanization

Hepburn romanization (ヘボン式) is the most widely used system internationally, developed by James Curtis Hepburn in 1867 and revised into its modern form in the early 20th century. It prioritizes phonetic intuition for English speakers: し is spelled "shi", ち is "chi", つ is "tsu", ふ is "fu", and じ is "ji". The modified Hepburn system (used today) adds macrons over long vowels — ō for おう/おお and ū for うう — though many informal usages omit macrons. Hepburn is used on Japanese passports, street signs, official government transliterations, and most international contexts. If you need romaji that non-Japanese readers can pronounce correctly without learning Japanese phonology, Hepburn is the best choice.

Kunrei-shiki romanization (訓令式) is the system taught in Japanese elementary schools and standardized by the Japanese government in 1937. It prioritizes systematic consistency over phonetic representation for English speakers: し is "si", ち is "ti", つ is "tu", ふ is "hu", and じ is "zi". This makes the system more regular (each row of the kana chart maps to a single consonant), but produces spellings that look unusual to non-Japanese readers. Nihon-shiki (日本式) is the original pre-war Japanese romanization system and is the most linguistically consistent — it follows Japanese phonological rules exactly. Both systems are used in academic linguistics and some government documents, but Hepburn remains dominant for general use and Japanese language learning materials.

Three kana features require special handling in romanization. First, long vowels (ā, ī, ū, ē, ō) are written with macrons in strict Hepburn (e.g., tōkyō for 東京) but are often doubled in academic contexts (Tookyoo) or simply omitted in casual usage (Tokyo). Second, the small っ/ッ (sokuon) represents a geminate consonant — a held or doubled consonant. In romaji, this is written by doubling the next consonant: きって becomes "kitte", ざっし becomes "zasshi", and はっぱ becomes "happa". Before a "ch" sound (ちっち), it becomes "cch" (tcchi in Nihon-shiki). Third, ん/ン (n) is romanized as "n" before consonants but as "n'" before vowels or y to distinguish it from な (na), に (ni), etc.: さんい (san'i, "praise") vs. さに (sani).

Most Japanese speakers on computers and smartphones input Japanese text using a romaji-based Input Method Editor (IME). The IME accepts romaji keystrokes and converts them to hiragana, which is then converted to kanji or katakana via the IME's dictionary. For example, typing "nihongo" produces にほんご, and pressing the space key offers conversion options including 日本語. This means software developers working with Japanese input need to understand how romaji maps to kana — for example, testing that an input field correctly accepts "shi" and produces し. Debugging IME input issues is easier when you understand the underlying romanization system being used (Windows uses modified Hepburn, macOS uses Hepburn).

For Japanese language learners, romaji serves as a phonetic scaffold when reading kana is not yet fluent. However, relying on romaji too long can slow kana acquisition — most Japanese language educators recommend transitioning away from romaji as quickly as possible. This converter is useful for checking the pronunciation of unfamiliar kana combinations, generating furigana-like annotations for study materials, and creating pronunciation guides for names or vocabulary. When creating Japanese-language content for international audiences (menus, brochures, presentations), Hepburn romaji is the correct choice for pronunciation guides, as it is the system non-Japanese readers are most likely to interpret correctly.