Japanese Numbers: How to Count from 1 to 100,000,000 (and Beyond)

Japanese numbers use two systems side by side, and they group large numbers in blocks of ten thousand rather than thousands.¹ This article builds the foundation for every counter word. It also tackles the hardest adjustment for English speakers: the 万-block grouping.

Overview: Two Number Systems Running in Parallel

To count in Japanese, you need two parallel sets of number words: the Sino-Japanese set and the native Japanese set.¹ One does almost all the everyday work. The other survives in a handful of common, fixed uses.

Both systems have coexisted since Chinese literacy entered Japan. The native set is older. The Sino-Japanese set is the borrowed layer that grew to dominate.¹

The Sino-Japanese set (いち, に, さん): the productive default

The Sino-Japanese series is the on'yomi (音読み, the Chinese-derived reading) set borrowed from Chinese: いち・に・さん…じゅう.¹ It is the productive default. It does most of the work in math, prices, phone numbers, dates, time, and most counters.

The full 1–10 series is いち (1), に (2), さん (3), し / よん (4), ご (5), ろく (6), しち / なな (7), はち (8), きゅう / く (9), じゅう (10).¹ Because these readings combine cleanly and predictably, they are the basis for large-number expressions (百, 千, 万, 億, 兆) and compound numbers such as 二十五 (にじゅうご, 25).¹

The native Japanese set (ひと, ふた, み): effectively 1–10

The native series is the Yamato, or kun'yomi (訓読み), layer: ひと・ふた・み・よ・いつ・む・なな・や・ここの・とお for 1–10.¹ Add the general counter つ, and you get the everyday object-counting words ひとつ・ふたつ・みっつ・よっつ・いつつ・むっつ・ななつ・やっつ・ここのつ, with the bare とお covering 10 (no つ).¹

The native series is largely limited to 1–10. Above 10, Japanese switches to the Sino-Japanese set, and there is no productive native series past that.¹ It survives in three durable pockets: the general つ counter (ひとつ, ふたつ…), the native-reading days of the month 一日〜十日 and 二十日 (はつか), and fixed words such as 一人 (ひとり) and 二人 (ふたり).¹²

The native set is limited in range, not obsolete

ひとつ and ふたつ are among the most common counting words in everyday speech, since they count unclassified objects. Treat the native set as restricted in scope, not as archaic or rare.¹

Which set a learner reaches for first

For beginners, the practical rule is to default to the Sino-Japanese set (いち・に・さん).¹ The native set appears only in the specific pockets named above and in the dedicated counter material, so learn it pocket by pocket rather than as a general-purpose series.¹

How to Count 1 to 10

Most learners start with 1–10. This is also where the double readings for 4, 7, and 9 first appear.

The 1 to 10 table: kanji, Sino-Japanese, and native readings side by side

The table below puts the kanji, the Sino-Japanese (on) reading, the native object-counting form with つ, and the bare native stem side by side.¹ All readings are in kana, so they stay legible without ruby inside the cells.

Digit	Kanji	Sino-Japanese (on)	Native + つ (kun)	Bare native stem
1	一	いち	ひとつ	ひと
2	二	に	ふたつ	ふた
3	三	さん	みっつ	み
4	四	し / よん	よっつ	よ
5	五	ご	いつつ	いつ
6	六	ろく	むっつ	む
7	七	しち / なな	ななつ	なな
8	八	はち	やっつ	や
9	九	きゅう / く	ここのつ	ここの
10	十	じゅう	とお	とお

The digits 4, 7, and 9 each have two Sino-Japanese readings. The everyday choices are よん, なな, and きゅう, covered in the next section.¹ The native counting words appear when general objects are counted.

猫ねこは耳みみが二ふたつある。³
"A cat has two ears."

2ふたつとも買かいます。⁴
"I'll buy both of them."

4, 7, and 9: the readings that switch (よん/し, なな/しち, きゅう/く)

When you say numbers by themselves, よん (4), なな (7), and きゅう (9) are the preferred everyday readings. し, しち, and く are the older Sino-Japanese readings that survive in many established words.¹

よん is preferred over し partly because し sounds the same as 死 ("death"). This is a durable, well-established avoidance rather than a passing trend.¹⁵⁶ なな is often preferred over しち because しち is easy to confuse with いち (1), especially over the phone or in noisy rooms. しち still survives in fixed forms such as 七時 (しちじ, "seven o'clock").¹

The reading く (9) survives in fixed compounds such as 九時 (くじ, "nine o'clock") and 九月 (くがつ, "September"). By itself and in most arithmetic, the reading is きゅう.¹

Which reading wins is fixed per word, not chosen freely

The choice between readings is lexicalized, meaning fixed by the word: 四月 is always しがつ (April), 四時 is always よじ (four o'clock), 七時 is しちじ, and 九時 is くじ. Beginners memorize these per word rather than deriving them. The systematic per-counter rules belong to the dedicated counter material.¹

How to Count 11 to 9,999

Above 10, Japanese numbers are fully regular. They are built by combination, so once you see the pattern, you can read the whole range.

Tens, hundreds, thousands: 十, 百, 千 and the stacking rule

Numbers above 10 are built by addition and multiplication, with no separate words for "twenty" or "thirty."¹ The unit words are 十 (じゅう, 10), 百 (ひゃく, 100), and 千 (せん, 1000). A multiplier digit comes before the unit, and the remaining digits stack to the right.¹

So 11 = 十一 (じゅういち), 25 = 二十五 (にじゅうご, literally "two-ten-five"), and 325 = 三百二十五.¹ Unlike English, 百 means exactly 100 and 千 means exactly 1000. Normally, there is no multiplier on the leading 1 (not いちひゃく).¹

この部屋へやは三百さんびゃく人にん収容しゅうようできる。⁷
"This room can hold three hundred people."

この建物たてものは三百さんびゃく年ねん前まえに建たてられました。⁸
"This building was built three hundred years ago."

The sound changes inside 百 and 千 (さんびゃく, ろっぴゃく, はっぴゃく, さんぜん)

Some hundreds and thousands have predictable sound shifts. Inside 百 (ひゃく): 300 = 三百 (さんびゃく), 600 = 六百 (ろっぴゃく), and 800 = 八百 (はっぴゃく). The other hundreds (200 にひゃく, 400 よんひゃく, 500 ごひゃく, 700 ななひゃく, 900 きゅうひゃく) are regular.¹

Inside 千 (せん): 3000 = 三千 (さんぜん) and 8000 = 八千 (はっせん) shift, while 1000 is just 千 (no multiplier on 1). The others (2000 にせん, 4000 よんせん, 5000 ごせん, 6000 ろくせん, 7000 ななせん, 9000 きゅうせん) are regular.¹

These are the same gemination and sequential-voicing (連濁, rendaku) processes that drive the broader counter irregularities. Here, they appear inside the number itself. The full counter sound-change system belongs to the dedicated counter material.¹

Treat the shifted forms as the correct reading, not a variant

The shifts are obligatory: *さんひゃく and *はちひゃく are simply not used. Learn さんびゃく, ろっぴゃく, and はっぴゃく as the standard readings, not optional variants.¹

家いえに来きた年賀状ねんがじょうは、三百さんびゃく枚まいほどで…⁹
"The New Year's cards that came to the house numbered about three hundred…"

The 万 System: Why Japanese Groups by 10,000, Not 1,000

This is the central adjustment for English speakers. Japanese large-number units step up by powers of 10,000. As a result, the spoken units do not line up with the three-digit commas of a written figure.

Powers of ten thousand: 万 (10^4), 億 (10^8), 兆 (10^12), 京 (10^16)

Japanese follows the East Asian myriad system: large-number units step up by powers of 10,000, not 1,000.¹ Each unit is 10,000 times the one before it.

Unit	Reading	Power of ten	Value
万	まん	10^4	ten thousand
億	おく	10^8	one hundred million
兆	ちょう	10^12	one trillion
京	けい	10^16	ten quadrillion

A million has no dedicated word: it is 百万 (ひゃくまん), literally "hundred ten-thousands" (100 × 10^4).¹ The leading 1 is dropped on the lower units but kept from 万 upward: 100 is 百 and 1000 is 千, but 10,000 is 一万 (いちまん) and 100,000,000 is 一億 (いちおく).¹

兆, 京, and 零 are recognition vocabulary, not N5 production load

The large-number tail (兆 at 10^12, 京 at 10^16) and the formal zero kanji 零 sit above N5 in practice. 京 is real and standardized, but it is rarely needed outside finance, science, and supercomputer names (the 京 "Kei" computer was named for its 10^16 operations per second). At the beginner stage, treat these as forms to recognize, not forms you need to produce.¹

宇宙うちゅうには何なん百万びゃくまんもの星ほしがある。¹⁰
"There are millions of stars in the universe."

億万長者おくまんちょうじゃで、百万長者ひゃくまんちょうじゃではない。¹¹
"Tom is a billionaire, not a millionaire."

Reading a price or population: regroup commas in your head

The core reading skill is re-chunking. Japanese still writes Arabic numerals with commas every three digits (the Western convention), but the spoken units group every four digits.¹ So 1,000,000 is not read from its commas. It must be re-grouped as 100 × 10,000 = 百万.¹

The mechanical method is to count four digits in from the right to find the 万 boundary.¹ The diagram below shows that re-grouping for three common figures.

損害そんがいは百万ひゃくまんドルにのぼる。¹²
"The loss amounts to a million dollars."

もし百万ひゃくまんドルあれば、どうしますか。¹³
"What would you do if you had a million dollars?"

Where the systems diverge: English "million/billion" has no clean Japanese equivalent

English large-number words do not map one-to-one onto Japanese units. English "million" is 百万 (hundred × ten-thousand), English "billion" (10^9) is 十億 (じゅうおく, ten × hundred-million), and English "trillion" (10^12) is 一兆 (いっちょう).¹

Because the grouping bases differ (English 1,000 against Japanese 10,000), you cannot translate "billion" as if it had its own single Japanese unit. You have to assemble it as 十億.¹ This is the central adjustment for English-speaking readers.

Reading Zero, Decimals, and Negatives

Zero, the decimal point, and negative numbers each raise a small but common reading question. None is hard once you know the conventions.

Zero: ゼロ vs れい vs 〇 vs 零

The digit 0 has several spoken forms. ゼロ is a loanword (from English "zero" and French "zéro") and is the most common everyday reading. れい is the Sino-Japanese reading. It is more formal and historically dominant in counting, measurements, temperatures, and the start of a decimal.¹¹⁴

The form 〇 (まる, literally "circle") is read aloud when reciting digits one at a time, as in phone numbers and codes. It works like saying "oh" for 0 in English.¹ The kanji 零 is the formal written form (on'yomi れい). It is rare in everyday text but present in formal, technical, and set expressions such as 零下 (れいか, "below zero").¹

For decimals, れい is the conventional reading for the leading zero (零点〜 / れいてん〜). After the point, the digits may be read with either れい or ゼロ.¹¹⁴

NHK's broadcast standard for 0, with one dated change

NHK historically set れい (broadcast "レー") as the basic reading of 0, to keep it consistent with the other Sino-Japanese digits. From fiscal year 2026, NHK changed its rule for telephone numbers and postal codes to "either is acceptable, ゼロ preferred." For learners, the main point is simply that both ゼロ and れい are accepted. The FY2026 detail is institutional broadcast policy.¹⁴

Decimal points with 点 (てん)

The decimal point is spoken as 点 (てん, "point"). The digits after it are read one at a time rather than as a grouped number.¹ Wikipedia gives 252.255 read as にひゃくごじゅうにてんにごご.¹

By the same rule, 3.14 is read 三点一四 (さんてんいちよん), and 0.5 is 零点五 (れいてんご). These two are simple constructed examples of the rule rather than corpus-sourced sentences.¹

Negative numbers with マイナス

Negative numbers and "below zero" are expressed with the loanword マイナス before the figure. It is a straightforward borrowing of English "minus."¹

気温きおんはマイナス6ろく度どです。¹⁵
"It's six degrees below zero."

昨夜さくや、温度計おんどけいはマイナス10じゅう度どを示しめした。¹⁶
"The thermometer registered minus ten last night."

Standalone Numbers vs. Counter Forms

A number's reading can shift when it attaches to a counter. This is the bridge from the number system into the counter system.

Why 四 is よん alone but よ in 四時 (よじ)

Standing alone, 4 is よん. Before the counter 時 (じ, o'clock), it becomes よ, giving 四時 = よじ ("four o'clock").¹ The same よ appears in 四人 (よにん, "four people") and inside 二十四時間 (にじゅうよじかん, "twenty-four hours").¹

The parallel shifts for 7 and 9 in time are しちじ (seven o'clock) and くじ (nine o'clock). Here, the older Sino-Japanese readings しち and く are the fixed forms, not なな and きゅう.¹ These shifts are lexicalized, or fixed by each counter, so this section only previews the principle. The full inventory belongs to the dedicated counter material.¹

The diagram below shows how a single digit forks into different readings depending on what follows it.

四時よじまで待まちます。¹⁷
"I'll wait till four o'clock."

会議かいぎは午後ごご四時よじに終おわった。¹⁸
"The meeting ended at 4:00 p.m."

私わたしは四人よにん姉妹しまいではありません。¹⁹
"I am not one of four sisters."

一日いちにちは二十四にじゅうよ時間じかんある。²⁰
"A day has twenty-four hours."

A first look at counters: the number plus a measure word

Japanese cannot count most bare nouns directly. Counting requires a counter (a measure word) attached to the number, as in 三百人 (さんびゃくにん, "300 people") or 三百枚 (さんびゃくまい, "300 flat objects").¹ The number and counter fuse into one word read as a unit, which is exactly where the reading shifts above come from.

Choosing the right counter for a noun and reading the resulting fused form is the work of the dedicated counter material. This article sets the foundation for that.¹

この部屋へやは三百さんびゃく人にん収容しゅうようできる。⁷
"This room can hold three hundred people."

Good to know

The 万-comma mismatch trap

A common error is reading a 万 figure straight from its commas, parsing 1,000,000 as if the commas marked the spoken units. Instead, re-group the figure four digits at a time.

100ひゃく万まん¹
"one million (100 ten-thousands)"

Japanese writes Arabic numerals with three-digit commas (the Western convention) but speaks them in four-digit (万) blocks. The written commas and the spoken units do not line up.¹ A reliable fix is to cover the last four digits with a finger to find the 万 boundary.

Why 4 and 9 carry superstition

The digit し (4) sounds the same as 死 ("death"), and く (9) sounds the same as 苦 ("suffering, pain"). The combination 49 (し-く) suggests 死苦 and is especially avoided.⁵⁶²¹ Hospitals, hotels, and some buildings skip floor and room numbers containing 4 (and sometimes 9), and people avoid gift quantities of 4.

This is a durable, long-standing pattern (East Asian tetraphobia), not a passing trend. It reinforces the everyday preference for よん and きゅう over し and く.⁵⁶²¹

When native readings still surface

The native series never fully disappears. It appears in ひとつ・ふたつ for general objects, in the native-reading days of the month 一日 (ついたち), 二日 (ふつか), 三日 (みっか) through 二十日 (はつか), and in fixed people-words 一人 (ひとり) and 二人 (ふたり).¹²

The word 一日 (ついたち), meaning the first of the month, is a worn-down 月立ち ("month-rising," the start of the month).¹²

Picking the right zero form for the register

Use 〇 (まる) or ゼロ when reciting a phone number digit by digit. れい fits formal, measurement, and decimal-leading contexts. ゼロ fits casual arithmetic and everyday speech.¹¹⁴ The choice is set by context rather than free, so a register-wrong form (for example まる in a formal temperature reading) sounds off even though it names the same digit.¹¹⁴

A mnemonic for the big units: they climb in ten-thousands

The large units run 万 → 億 → 兆 → 京, each ×10,000 (10^4 → 10^8 → 10^12 → 10^16).¹ Pair each kanji with its power of ten, always a multiple of 4. This makes the otherwise opaque jump from 億 to 兆 predictable.¹

See also

• Counters in Japanese: An Overview of 助数詞 (Josūshi)
• Counters by Category: A Reference Index
• 人 / 名 (Nin/Mei) Counter: Counting People in Japanese
• Japanese Money and Shopping Vocabulary: 円, 買う/売る/払う, and いくらですか
• Time, Date, and Calendar Vocabulary in Japanese
• The JLPT Explained: Levels, Sections, and What Each Means

References

Footnotes

1. "Japanese numerals." Wikipedia. https://en.wikipedia.org/wiki/Japanese_numerals (encyclopedic; cross-checked against the references below for every load-bearing claim). ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴ ↩¹⁵ ↩¹⁶ ↩¹⁷ ↩¹⁸ ↩¹⁹ ↩²⁰ ↩²¹ ↩²² ↩²³ ↩²⁴ ↩²⁵ ↩²⁶ ↩²⁷ ↩²⁸ ↩²⁹ ↩³⁰ ↩³¹ ↩³² ↩³³ ↩³⁴ ↩³⁵ ↩³⁶ ↩³⁷ ↩³⁸ ↩³⁹ ↩⁴⁰ ↩⁴¹ ↩⁴² ↩⁴³ ↩⁴⁴ ↩⁴⁵ ↩⁴⁶ ↩⁴⁷ ↩⁴⁸ ↩⁴⁹ ↩⁵⁰ ↩⁵¹ ↩⁵² ↩⁵³ ↩⁵⁴ ↩⁵⁵ ↩⁵⁶ ↩⁵⁷ ↩⁵⁸ ↩⁵⁹

2. "Japanese calendar." Wikipedia. https://en.wikipedia.org/wiki/Japanese_calendar (native-reading date forms 一日〜二十日). ↩ ↩² ↩³

3. Tatoeba sentence #1585523. https://tatoeba.org/en/sentences/show/1585523 ↩

4. Tatoeba sentence #11052369. https://tatoeba.org/en/sentences/show/11052369 ↩

5. "Tetraphobia." Wikipedia. https://en.wikipedia.org/wiki/Tetraphobia ↩ ↩² ↩³

6. "Japanese superstitions." Wikipedia. https://en.wikipedia.org/wiki/Japanese_superstitions ↩ ↩² ↩³

7. Tatoeba sentence #220000. https://tatoeba.org/en/sentences/show/220000 ↩ ↩²

8. Tatoeba sentence #2392265. https://tatoeba.org/en/sentences/show/2392265 ↩

9. Tatoeba sentence #11015425. https://tatoeba.org/en/sentences/show/11015425 ↩

10. Tatoeba sentence #189886. https://tatoeba.org/en/sentences/show/189886 ↩

11. Tatoeba sentence #10610034. https://tatoeba.org/en/sentences/show/10610034 ↩

12. Tatoeba sentence #139333. https://tatoeba.org/en/sentences/show/139333 ↩

13. Tatoeba sentence #193464. https://tatoeba.org/en/sentences/show/193464 ↩

14. 日本放送協会（NHK）放送文化研究所. 数字「0」の読み方に関する取り扱い（電話番号・郵便番号について「①ゼロ ②レー」、2026年度より「ゼロ」を優先）. https://www.nhk.or.jp/bunken/ (NHK Broadcasting Culture Research Institute; the FY2026 standard change is the one dated claim in this document). ↩ ↩² ↩³ ↩⁴ ↩⁵

15. Tatoeba sentence #2281525. https://tatoeba.org/en/sentences/show/2281525 ↩

16. Tatoeba sentence #169712. https://tatoeba.org/en/sentences/show/169712 ↩

17. Tatoeba sentence #921354. https://tatoeba.org/en/sentences/show/921354 ↩

18. Tatoeba sentence #185360. https://tatoeba.org/en/sentences/show/185360 ↩

19. Tatoeba sentence #2349192. https://tatoeba.org/en/sentences/show/2349192 ↩

20. Tatoeba sentence #190268. https://tatoeba.org/en/sentences/show/190268 ↩

21. Tofugu, "The Number Four: Why Do Japanese People Fear It?" https://www.tofugu.com/japan/number-four-superstition/ (language-learning publisher; used only to corroborate the 死/苦 homophony framing already attested in ⁵ and ⁶). ↩ ↩²