How Japanese Numbers Work

The Basics

Two ways to count: 訓 and 音

Japanese carries two parallel number systems. The native set (訓読み, kun'yomi) runs ひとつ・ふたつ・みっつ; inherited from old Japanese, it counts objects directly. The borrowed Sino-Japanese set (音読み, on'yomi) runs いち・に・さん, came from Chinese, and handles everything abstract: math, money, phone numbers, dates, measurements.

The Sino-Japanese series is the backbone — it scales without limit and powers almost everything you will read. The native series survives mainly in the universal つ counter and a few set phrases, and it stops dead at ten. Informally it also appears in young children's ages: a two-year-old is ふたつ before the family switches to the more formal 〜歳 (〜さい). The rest of this guide builds on the Sino-Japanese set; for where the native set still earns its keep, see つ and 個, the universal counters.

How Numbers Are Built

Digit + place: 十・百・千

Below 10,000 the Sino-Japanese system is positional and almost perfectly regular. Three place markers do all the work, and you read them left to right exactly as written.

There are no "teen" words and no "twenty/thirty" words to memorize — you compose them. 11 is ten-one → 十一 (じゅういち). 20 is two-ten → 二十 (にじゅう). 47 is four-ten-seven → 四十七 (よんじゅうなな). The digit on the left multiplies the place; the digit on the right adds to it.

Once you can build 47, you can build every two-digit number — the rule never changes below 100. The same digit + place logic then repeats with 百 and 千: 三百四十七 is three-hundred four-ten-seven → 347.

Where the Pattern Bends

Two things to watch

Good news first: the construction itself is regular. Two small wrinkles trip people up, though, and neither is scary. First, three of the digits carry two readings, and you have to choose. In everyday counting, よん, なな, and きゅう dominate — partly habit, partly because し and く are avoided for sounding like "death" and "suffering."

Second, a handful of digit-place combinations change sound when spoken: 300 is さんびゃく, not さんひゃく; 600 is ろっぴゃく; 8,000 is はっせん. There are only five base cases, and they are euphonic, not random. The number irregulars guide walks through the why behind each one.

Going Bigger

Past 9,999: the 万 jump

English groups large numbers in threes: thousand, million, billion, with a comma every three digits. Japanese groups in fours. Above 9,999 a new unit takes over: 万 (まん) = 10,000, and it becomes the counting base. So 100,000 is not "hundred-thousand" but 十万 (じゅうまん), literally ten 万, and 1,000,000 is 百万 (ひゃくまん), a hundred 万.

A useful early anchor: Japan's currency operates in yen, and because ¥1 is roughly one US cent, prices hit the 万 range fast. The ¥10,000 note — いちまんえん — is the largest standard banknote. Hotel rates, electronics, and salaries push well into the 万s; knowing the unit means you can follow a price conversation without pausing to convert. That makes 万 one of the most immediately practical items on the list.

This three-versus-four-digit mismatch is the single biggest hurdle for English speakers reading large numbers, and it deserves its own walkthrough; see counting big with 万・億・兆.

Common Questions

Quick answers

From Knowledge to Fluency

Why reading the chart isn't enough

Understanding the digit + place rule takes about five minutes. Producing 四十七 the instant you see 47 — without counting it out in your head — is a different skill, and it is the one that matters when a clerk says a price or a number flies past in a listening test.

Active recall builds that reflex: see a number, say the reading before it is revealed, and let the misses teach you. Twenty focused reps is worth more than re-reading this page five times.