Numbers Written in Kanji

Japanese writes numbers two ways: with the Arabic digits you already know (1, 2, 3) and with kanji numerals (一, 二, 三). Both are everywhere, and choosing between them is not random — it tracks the direction of the writing, the register, and long-standing convention. This page covers the kanji numerals themselves, how they stack up into larger numbers, and, crucially for an English speaker, the one place where Japanese counting works on a completely different rhythm from ours.

The basic numerals

The building blocks run one through ten, plus three "big place" characters:

Building numbers by place value

Kanji numbers are assembled from the highest place down, reading left to right, by combining a multiplier with a place word. So 二十三（にじゅうさん）, nijūsan, is literally "two-ten-three" = 23. There is no separate word for "twenty" — it is transparently two tens.

The big trap: Japanese groups by 万 (10,000), not by 1,000

This is the single most important thing an English speaker must internalize, and it is worth slowing down for. English inserts a comma — and a new number word — every three digits: thousand, million, billion. Japanese inserts a new place word every four digits, at 万 (10,000), 億（おく, oku, 100,000,000), and 兆（ちょう, chō, one trillion).

The consequence is that big numbers do not line up with their English names. "One million" is not a single unit in Japanese — it is 百万（ひゃくまん, hyakuman）, "one hundred ten-thousands." Ten thousand, which English treats as merely "ten thousand," gets its very own character, 万, precisely because it is the pivot of the whole system.

Kanji numerals vs. Arabic digits: which to use

Both systems coexist, and educated writers switch fluidly. The deciding factor is usually the orientation and register of the text.

Kanji numerals dominate when the text is:

• Vertical (縦書き（たてがき）, tategaki). Novels, newspaper columns, and vertical signage read top-to-bottom, and kanji numerals rotate naturally into that flow, whereas Arabic digits would have to be turned on their side or stacked awkwardly. See Vertical and Horizontal Writing.
• Formal, literary, or legal. Contracts, certificates, and elegant menus lean on kanji.
• A set expression. Idioms lock in kanji numerals: 一石二鳥（いっせきにちょう, isseki-nichō, "two birds with one stone"), 十人十色（じゅうにんといろ, jūnin-toiro, "different strokes for different folks"), 一期一会（いちごいちえ, ichigo-ichie, "once-in-a-lifetime encounter").

Arabic digits dominate when the text is:

• Horizontal (横書き, yokogaki) — most modern signage, email, and web text.
• Technical or mathematical — prices on receipts, phone numbers, statistics, measurements.

The formal "daiji" numerals

Here is a detail worth knowing that most textbooks skip: there is a second, more elaborate set of numeral kanji called 大字（だいじ, daiji）, used on contracts, official receipts, and bank forms specifically to prevent fraud. The everyday 一, 二, 三 are dangerously easy to alter — a single added stroke turns 一 into 二 or 三, and 千 into a larger figure. The daiji forms are visually complex, so they cannot be doctored.

So a cheque for ¥30,000 is written 金参萬円 rather than 三万円. You will rarely need to write daiji, but you should recognize them on any official document.

A quick word on zero

Zero has no classical kanji of its own in the counting system. In speech it is ゼロ (zero) or 零（れい, rei); in vertical or formal writing it is written 〇 (a circle, read maru or zero), for example in a positional-style year like 二〇二六年（にせんにじゅうろくねん, nisen-nijūroku-nen, "the year 2026").

Common mistakes

The mistake that trips up nearly every English speaker is the first one — the four-digit grouping. Drill it directly: 万 is the hinge, and once you can convert "how many ten-thousands?" instead of "how many thousands?", the whole large-number system clicks. The rest is just recognizing which script to use for the situation in front of you.

Key takeaways

• The building blocks are 一〜十 plus the place words 百, 千, 万 (and 億, 兆 higher up); numbers stack from the highest place down.
• Japanese groups large numbers by 万 = 10,000, not by thousands — "a million" is 百万, "hundred myriad."
• Kanji numerals go with vertical, formal, and idiomatic text; Arabic digits with horizontal and technical text. The daiji forms (壱, 弐, 参…) exist to stop fraud on official documents.