Translation guide
In Japanese, expressing that two or more people are the same age is usually done with specific nouns or set phrases rather than a direct adjective. The most common and natural way is to use 同い年 (おないどし) or 同じ年 (おなじとし). There are also more formal or written terms like 同年 (どうねん) and 同級生 (どうきゅうせい) for classmates of the same grade. When referring to oneself and someone else, you can say 同い年です or 同じ年です.
To say that two or more people are the same age in casual or everyday conversation.
The most common and natural word for 'same age'. Used in casual and polite speech. Can be used as a noun or with です.
私と彼は同い年です。
He and I are the same age.
同い年の友達がたくさんいます。
I have many friends who are the same age as me.
Literally 'same year'. Slightly more literal than 同い年 but still common. Can be used interchangeably in most cases.
私たちは同じ年です。
We are the same age.
Formal or written term for 'same year/age'. Often used in official documents or news.
彼らは同年の生まれです。
They were born in the same year.
To refer to someone who is in the same school year or grade, implying they are usually the same age.
Means 'classmate' or 'person in the same grade'. While it focuses on school year, it strongly implies being the same age in Japanese school context.
彼は私の同級生です。
He is my classmate (and the same age as me).
Refers to someone who entered a school or company in the same year. Often implies same age, but not always. Common in work contexts.
To ask if someone is the same age or to state that you are the same age as someone else.
Pattern: [Person] と同い年です. Use this to say you are the same age as someone.
田中さんと同い年です。
I'm the same age as Tanaka-san.
Polite way to ask 'Are you the same age?'. Can be used with 〜と to specify the other person.
彼と同い年ですか？
Are you the same age as him?
Do not try to translate 'same age' word-for-word as 同じ年齢 (おなじねんれい). While grammatically correct, it sounds unnatural and overly formal. Stick to 同い年 or 同じ年.
In Japanese culture, age differences affect speech politeness. Being the same age often allows for more casual speech (タメ口, ためぐち). You might hear タメ as slang for 'same age' among younger people.
He entered university the same year as me.