expression
for one's age; considering one's age
Used to express that something is unexpected or noteworthy relative to a person's age. Often followed by a statement of surprise or contrast.
彼は年の割に若く見える。
He looks young for his age.
年の割にしっかりした意見を持っている。
She has well-formed opinions for her age.
More formal synonym; 年の割に is more common in everyday speech.
Phrase composed of 年 (year/age), の (possessive particle), 割 (proportion/ratio), and に (adverbial particle). Literally 'in proportion to one's age'.