Arabic numerals to Japanese kanji

2017-02-05

Convert Arabic numerals, the digits 0 through 9, into Japanese kanji. For example, 2342342 becomes 二百三十四万二千三百四十二.

The characters overlap with Chinese numerals, but this converter follows Japanese conventions. It is not a general Chinese number formatter.

Number to convert

Convert

Enter up to 72 integer digits, with an optional sign and decimal part. Use digits without commas or scientific notation.

How it works

Japanese large-number units advance every four digits: 万 is 10,000, 億 is 100,000,000, and 兆 is 1,000,000,000,000.

Split the integer into groups of four digits from the right. Within each group, turn the thousands, hundreds, tens, and ones into kanji. Skip zero digits and omit 一 before 十, 百, and 千. Attach the group’s large-number unit, then join the nonzero groups from left to right.

For 2342342, the groups are 234 and 2342. They become 二百三十四万 and 二千三百四十二.

Zero is 〇. A negative value gets マイナス in front. After a decimal point, convert each digit separately, so -12.05 becomes マイナス十二.〇五. Leading zeros do not change the value.

The code reads the input as text rather than a JavaScript number, keeping every digit intact even beyond JavaScript’s exact integer range.