漢 Text & Writing

Kanji Numeral & Daiji Converter

Convert between Arabic numerals, Japanese kanji numerals (positional) and daiji (だいじ). Edit any one field and the others update instantly. Daiji are the old, tamper-proof kanji (壱・弐・参…) that Japan uses for amounts on receipts, contracts and legal registrations. Big values stay exact thanks to BigInt, and everything runs in your browser.

Examples (click to try)

Type a whole number into the Arabic field and it is converted to kanji and daiji on the spot.

How to use the kanji numeral converter

Edit any one of the three fields — Arabic numeral, kanji numeral or daiji — and the other two convert on the spot. Grab any value with its Copy button.

  • Enter from any field: Arabic 12345, kanji 一万二千三百四十五 or daiji 壱萬弐仟参佰肆拾伍 all convert to each other.
  • Daiji: 一→壱, 二→弐, 三→参, 十→拾, 百→佰, 千→仟, 万→萬 — the tamper-resistant old forms (億 / 兆 / 京 are left unchanged).
  • Money format: tick "金 … 円" and the daiji field becomes a receipt-style amount such as 金壱萬円.
  • Handles big numbers: BigInt is used internally, so large units like 兆 and 京 convert without rounding errors.

Why does Japan bother? A lone 一 (1) is one stroke, so a forger could add strokes to turn it into 二 (2) or 三 (3). The daiji form 壱 is far harder to alter, which is why amounts on Japanese receipts, contracts and property registrations are traditionally written this way. For example, type 20250 and you get kanji 二万二百五十 and daiji 弐萬弐佰伍拾; zero shows as 〇 in kanji and 零 in daiji.

Handy for

  • Writing an amount on a Japanese receipt or contract in tamper-proof daiji (壱・弐・参…)
  • Property registrations or notarized documents that require old-style kanji numerals
  • Filling in the amount on a Japanese gift envelope (ご祝儀袋) in kanji or daiji
  • Reading an amount written in kanji back into plain Arabic digits

FAQ

Is the data I enter sent to a server?
No. Everything is converted entirely in your browser, and the numbers or amounts you enter are never transmitted to or stored on any server, so you can use it with confidence.
What is daiji, and why is it used in Japan?
Daiji are complex, old-style forms of kanji numerals — 壱 弐 参 instead of 一 二 三. Because they have many strokes and distinct shapes, extra strokes cannot be added later to forge 一 into 二 or 三. In Japan they have long been used in the amount fields of receipts, contracts and property registrations to prevent tampering.
How large a number can it convert?
It uses JavaScript's BigInt internally, so even large units such as 兆 (trillion) and 京 (ten quadrillion) convert without rounding errors. It handles roughly the units above 京 (垓 to 極), which is far more than enough for everyday amounts.