Translation guide
How to express a number of years in Japanese, depending on context: duration, age, or a specific year count.
Expressing a period of time lasting a certain number of years.
The most common way to say 'N years' as a duration. The counter 年 (ねん) follows the number. Works for any number of years.
日本に3年住んでいます。
I have lived in Japan for three years.
このプロジェクトには5年かかりました。
This project took five years.
Explicitly emphasizes the duration. Often used when the time span is the focus, or to avoid ambiguity with a specific year (e.g., 2020年).
Stating someone's age in years.
The standard counter for age. Note the irregular readings for 1 (いっさい), 8 (はっさい), 10 (じゅっさい/じっさい), 20 (はたち).
娘は今年で6歳になります。
My daughter will be six years old this year.
祖父は90歳です。
My grandfather is 90 years old.
Referring to a number of years as a quantity, such as in statistics or comparisons.
年 (ねん) alone can mean both a specific year (e.g., 2020年) and a duration. Adding 間 (かん) makes it unambiguously a duration. Use 年間 when you want to emphasize the length of time, especially in sentences where 年 might be misinterpreted.
彼は3年日本にいた。
He was in Japan for three years. (Could also be interpreted as 'He was in Japan in the year 3' in some contexts, though unlikely.)
彼は3年間日本にいた。
He was in Japan for three years. (Clearly duration.)
When talking about age, always use 歳 (さい) or 才 (さい). Using 年 (ねん) for age is incorrect and would mean 'year' as in calendar year.
彼は10年間、教師として働いていました。
He worked as a teacher for ten years.
Emphasizes a long duration, often with a sense of 'as long as N years'. Used for highlighting the length of time.
彼女は20年もの間、この会社に勤めている。
She has been working at this company for as long as twenty years.
A simplified, informal variant of 歳, often used in casual writing or when the kanji is too complex. Same reading.
彼はまだ20才だよ。
He's still only 20 years old.
Means 'number of years' as a noun. Used in formal or technical contexts.
必要な勤続年数は3年です。
The required number of years of service is three.
A formal written pattern meaning 'N years'. Often used in reports or official documents.
この計画は5か年計画です。
This is a five-year plan.
彼は10歳です。
He is 10 years old.
彼は10年です。
(Incorrect for age; would mean 'He is the year 10' or similar.)
彼は10歳です。
He is 10 years old.
彼は10年です。
(Incorrect for age; would mean 'He is the year 10' or similar.)