Number ↔ Kanji Numeral Converter
Convert between Arabic numerals and Japanese kanji numerals. Supports both simple digit-by-digit substitution (一二三) and standard positional notation using 十/百/千/万/億 (百二十三).
Digit-to-kanji reference table
| Digit | Kanji |
|---|---|
| 0 | 〇 |
| 1 | 一 |
| 2 | 二 |
| 3 | 三 |
| 4 | 四 |
| 5 | 五 |
| 6 | 六 |
| 7 | 七 |
| 8 | 八 |
| 9 | 九 |
Positional unit reference table
| Unit | Value | Note |
|---|---|---|
| 十 | 10 | Written as 十, not 一十 |
| 百 | 100 | Written as 百, not 一百 |
| 千 | 1,000 | Written as 千, not 一千 |
| 万 | 10,000 | Written as 一万, not 万 — the opposite rule from 十/百/千 |
| 億 | 100,000,000 | Written as 一億, not 億 |
| 兆 | 1,000,000,000,000 | Written as 一兆, not 兆 |
What is the Number ↔ Kanji Numeral Converter?
This tool converts back and forth between Arabic numerals (123) and Japanese kanji numerals (百二十三). Japanese kanji numeral notation actually comes in two distinct styles: "simple digit substitution," which just swaps each digit for its kanji equivalent one by one (一二三), and "positional notation," which uses place-value units like 十, 百, 千, 万, and 億 to build the number the way it's actually written in formal Japanese (百二十三). This tool supports both.
You can switch modes depending on what you need: positional notation for situations that call for formal kanji numerals, such as contracts, invoices, or the addressee line on a New Year's card, or simple digit substitution for reading out a sequence of digits — like a phone number or PIN — in kanji exactly as they appear.
How to use the Number ↔ Kanji Numeral Converter
- Choose a conversion mode Pick "simple digit substitution" or "positional notation." For formal documents, choose positional notation.
- Choose a direction Pick "Number → Kanji" or "Kanji → Number," depending on which way you want to convert.
- Enter a number or kanji numeral Type the value you want to convert into the input field, and the result appears automatically.
- Copy the result Click the copy button to send the converted value straight to your clipboard.
Tips for getting more out of it
- The "positional notation" mode reproduces the formal kanji numerals actually used in Japanese writing and documents, such as 百二十三 for 123.
- The leading 一 (one) is dropped right before 十/百/千, but kept before 万/億/兆 (e.g. 1,000 → 千, but 10,000 → 一万). This asymmetric rule trips up even native Japanese speakers.
- The "simple digit substitution" mode is handy when you just want to read out a sequence of digits, like a phone number, one by one (e.g. 123 → 一二三).
- When converting kanji to a number, any character outside 〇–九 and 十/百/千/万/億/兆 will cause an error, so don't mix in full-width digits or Arabic numerals.
- The positional mode supports 0 through 9,999,999,999,999 (up to the 兆 / trillion place).
Ways to use the Number ↔ Kanji Numeral Converter
Amounts on contracts and invoices
Use positional notation mode to instantly generate the formal kanji numeral wording required on official Japanese documents.
Addresses and dates on New Year's cards or invitations
Handy for converting dates written in the Japanese style, such as 令和八年一月一日 (the first of January, Reiwa 8).
Learning how kanji numerals are read
Check the reference tables alongside the converter to study the rules for positional units like 十, 百, 千, 万, and 億.
Deciphering old documents
Use the kanji-to-number mode to translate kanji numeral notation found in historical documents into modern Arabic numerals.
Kanji numeral glossary
- Positional notation
- A way of writing kanji numerals that uses a distinct unit for each place value — 十, 百, 千, 万, 億, and so on — as in 百二十三 for 123.
- 万進法 (man-shinhō)
- The Japanese counting convention in which the unit name changes every 10,000 (万), unlike the English system, which introduces a new unit every 1,000.
- Daiji (大字)
- Special kanji numerals such as 壱, 弐, and 参, used to prevent tampering with amounts written on contracts and receipts.
- Digit grouping
- Splitting a large number into segments to make it easier to read. English uses commas every three digits (1,000), while Japanese kanji numerals split at the 万 and 億 positions instead.
- 〇 (maru)
- The kanji character for zero. Unlike the other kanji numerals, it carries no place-value unit of its own and is used as a standalone symbol.
Frequently Asked Questions
Side Note — Why Japanese groups numbers by 万 (10,000)
Western number systems, including English, group digits every 1,000: thousand, million, billion, each a thousand times the last. Japanese (along with Chinese, Korean, and other cultures that adopted Chinese characters) instead groups every 10,000: after 千 (thousand) comes 万 (10,000), then 億 (100,000,000). Because these grouping boundaries don't line up, converting large numbers between English and Japanese notation is a common source of confusion, especially for translators and international business.
This "myriad grouping" system, called 万進法 in Japanese, traces back to ancient Chinese numeral systems and was transmitted to Japan along with Chinese characters. It remains deeply embedded in everyday Japanese life — national budget figures, for instance, are almost always reported in 兆円 (trillion yen) or 億円 (hundred-million yen) rather than being translated into millions or billions.
There is also a separate, rarely-discussed set of kanji numerals called daiji (大字): 壱, 弐, 参 instead of 一, 二, 三. These are used specifically on financial documents like invoices, receipts, and contracts as a forgery-prevention measure — a single extra stroke could turn 一 into 二 or 三, but the more complex daiji characters are far harder to alter undetected. Traces of this convention survive today, for example on the decorative envelopes used for cash gifts in Japan, which are often inscribed with amounts like 金参万円也 using daiji.