Big Numbers in Japanese (Man, Oku, Chō)
English groups numbers by thousands (thousand, million, billion). Japanese groups by 10,000s (man, oku, chō). The unit shift is the single largest hurdle for English-speaking learners. Once it clicks, every big number falls out of the system.
The four major units
| Numeral | Kanji | Romaji | English equivalent |
|---|---|---|---|
| 10,000 | 万 | man | ten thousand |
| 100,000,000 | 億 | oku | one hundred million |
| 1,000,000,000,000 | 兆 | chō | one trillion (10^12) |
| 10,000,000,000,000,000 | 京 | kei | ten quadrillion (rare) |
From 10,000 to 100 million
| English | Kanji | Romaji |
|---|---|---|
| 10,000 | 一万 | ichi-man |
| 100,000 | 十万 | jū-man |
| 1,000,000 | 百万 | hyaku-man |
| 10,000,000 | 千万 | sen-man |
| 100,000,000 | 一億 | ichi-oku |
The chunk visualiser
Type any integer up to 999,999,999,999 and see it broken into 4-digit chunks aligned to the man, oku, and chō boundaries. Each chunk gets its own colour. The full Japanese reading appears below.
Why this trips up English speakers
When you read 100,000 in English, your eye chunks it as 100 + 1,000 → "one hundred thousand". A Japanese reader chunks the same number as 10 + 10,000 → "ten ten-thousand" (jū-man). The chunk boundary is in a different place. The simplest mental fix is to slide the comma. For Japanese reading, regroup digits in 4s: 12,345,678 becomes 1234,5678. From there, the reading drops out as 1234-man + 5678 (sen-nihyaku-sanjū-yon man, then go-sen rop-pyaku-nanajū-hachi).
Modern usage and the 4-digit comma
Japanese news, finance, and tax contexts use the man, oku, chō system everywhere. The Japanese government publishes budgets in oku and chō. Some Japanese primary schools and statistics agencies have started writing the comma every four digits to reflect the spoken grouping; this is documented but not yet standard. International business in Japan typically quotes both systems side by side.
Frequently asked questions
Why does Japanese group big numbers by 10,000 instead of 1,000?
Japanese inherited the 10,000 unit (man, 万) from classical Chinese, where 萬 was the next major unit after 千 (1,000). English groups by 1,000s because of how Latin and Old English shaped its number names. Both systems are internally consistent; the friction comes from converting between them. The practical fix: when reading a Japanese number, mentally place a comma every four digits instead of every three.
How do you say 1 million in Japanese?
1,000,000 is 百万 (hyaku-man), literally "hundred ten-thousands". Japanese has no single word for "million". Similarly: 10 million is 千万 (sen-man, "thousand ten-thousands"). 100 million is 一億 (ichi-oku), the next unit after man.
What is 億 (oku) in Japanese?
億 (oku) is the unit for 100,000,000 (one hundred million in English). Japanese counts in 4-digit groups: 万 (man, 10,000), 億 (oku, 100,000,000), 兆 (chō, 10^12). One billion in English is 10億 (jū-oku) in Japanese.
How do you say 1 trillion in Japanese?
1,000,000,000,000 is 一兆 (it-chō). The Sino-Japanese reading ichi shortens to it before the geminating chō, producing it-chō rather than ichi-chō. Used in Japanese government finance, scientific contexts, and astronomy.
Why is 一 dropped in front of 百 (hyaku) and 千 (sen)?
Convention: when no digit higher than the unit precedes it, ichi is dropped. So 100 = hyaku (not ichi-hyaku), 1,000 = sen (not ichi-sen). But 10,000 keeps the ichi: 一万 (ichi-man), because man is the boundary unit. Above man, all groups keep the leading digit.
Continue: numbers 1 to 100 · reading variations · prices in yen.