Why do Japanese units advance every four digits?

Japanese, like Chinese and Korean, uses a myriad system where each new unit is 10,000 times the last: 万 is 10,000, 億 is 100 million, and 兆 is one trillion. This differs from the Western system that groups every three digits.

What does the digit form like 1億2345万6789 mean?

It is the common mixed notation that keeps Arabic digits but inserts the kanji unit markers at each myriad boundary. It is widely used in Japanese newspapers and finance for readability of large numbers.

Why is 一 sometimes dropped?

Japanese omits 一 before 十, 百, and 千, so 1,000 is written 千 rather than 一千 and 15 is 十五. The tool follows this convention so the kanji reads naturally.

How large a number is supported?

The tool supports values up to the 京 (10 quadrillion) range within the safe-integer limit of JavaScript. Numbers beyond that are reported rather than mis-formatted.

Is my number uploaded anywhere?

No. The conversion runs locally in your browser with JavaScript, so nothing you type is sent to a server or stored.

Japanese Large Number Formatter

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Japanese groups large numbers every four digits, not every three, using the units 万, 億, and 兆. This tool converts an ordinary number into both the mixed digit form and full kanji numerals, applying the standard reading rules.

How it works

The number is split into 4-digit groups from the right and each non-zero group is tagged with its myriad unit:

万 = 10,000       (10^4)
億 = 100,000,000  (10^8)
兆 = 1,000,000,000,000 (10^12)
京 = 10^16

Within each group the digits use 千百十 and the kanji numerals 一-九, and a leading 一 is dropped before 十, 百, and 千. So 123456789 becomes the digit form 1億2345万6789 and the kanji form 一億二千三百四十五万六千七百八十九.

Example and notes

Entering 123456789 gives 1億2345万6789 and the full kanji reading above. The mixed digit form is what you will most often see in Japanese newspapers and financial reports, while the kanji form is used in formal writing. Everything is computed in your browser, so your input stays private.