Japanese Numbers and Counters: Readings, Ages, and Prices

Knowing that 1 is いち and 2 is に is only the beginning. In real Japanese, a number usually appears with a counter or unit, and that combination may change its sound. Four can be よん, よ, or し; seven can be なな or しち; nine can be きゅう or く. One book is not いちさつ but いっさつ, and one long object is いっぽん. The useful skill is therefore not “recite one through ten,” but “choose and pronounce the whole quantity.”

Start with the basic number readings

The alternative readings of four, seven, and nine are not interchangeable everywhere. Instead of asking which reading is universally “correct,” ask what is being counted. This keeps the choice tied to a real expression.

Four, seven, and nine change by context

A common beginner error is to make a combination mechanically, such as よんじ, ななじ, or きゅうじ. Those forms do not give the standard clock readings. Treat よじ, しちじ, and くじ as three complete vocabulary items.

Counters trigger sound changes

A Japanese counter classifies what you count. 冊 counts bound volumes, 本 counts long cylindrical objects, 匹 counts small animals, and 個 counts many small separate objects. The meaning of the counter matters, but so does its first sound. With counters beginning in h, the first consonant may become b or p; the number may also end in a short pause written with small っ.

Do not pronounce the spelling one character at a time. いち＋ほん does not remain ichi-hon; it becomes いっぽん, with a short closure before p. Likewise, さん＋ほん becomes さんぼん. The kana accurately shows the resulting sound.

People and ages contain their own exceptions

For people, one and two use native Japanese forms: 一人 is ひとり and 二人 is ふたり. From three onward, 人 is normally にん. Four people is よにん, not よんにん. 七人 is commonly しちにん; ななにん is also used when a speaker wants the number to be especially clear. The question word is 何人, read なんにん.

For age, use 数字＋歳. The main sound changes are 一歳 いっさい, 八歳 はっさい, and 十歳 じゅっさい or じっさい. Twenty years old is the special word 二十歳, はたち. Ages four, seven, and nine use よんさい, ななさい, and きゅうさい.

Prices use the large-number readings

Japanese groups large numbers by ten thousand, not by one thousand. The key units for shopping are 百 ひゃく, 千 せん, and 万 まん. Three hundred, six hundred, and eight hundred change sound: さんびゃく, ろっぴゃく, はっぴゃく. Three thousand and eight thousand are さんぜん and はっせん. Four hundred, seven hundred, and nine hundred use よんひゃく, ななひゃく, and きゅうひゃく.

Notice the contrast between exactly 4円, よえん, and 400円, よんひゃくえん. In a larger number, read each unit as part of the complete amount. Do not insert “and” as English does in some styles: 4,700 is simply よんせん ななひゃく.

Common errors and how to repair them

Practice: 14 answers you can score

1. Write the kana reading for 4 when it stands alone.
2. Write the standard reading of 四時.
3. Write the reading of 七人.
4. Write the reading of 九歳.
5. Write the reading of 一人.
6. Write the reading of 二十歳.
7. Choose the correct counter and reading for “one book”: 一（冊／本）.
8. Write the complete reading of 三本.
9. Write the complete reading of 六匹.
10. Write the complete reading of 八個.
11. Write 4,700円 in kana.
12. Correct this reading: 800円 = はちひゃくえん.
13. Complete “I bought six bottles of water”: 水を（　）買いました。
14. Complete “There are four people in my family”: 家族は（　）です。

Summary

Japanese numbers become usable when you learn the number, unit, and sound change together. Keep よん, なな, and きゅう as default readings, but memorize fixed combinations such as よじ, しちじ, くじ, よにん, and よえん. For counters, pay attention to small っ and the shifts from h to b or p. Practice whole quantities such as さんぼん, ろっぴき, はっさつ, はっぴゃくえん, and はたち instead of assembling them at the last second.