歳/才 (sai): Counting Age
Quick Answer: 歳 (or simplified 才) counts a person's age. Mostly regular: いっさい (1), にさい (2), さんさい (3)... Key irregular reading: 二十歳 = はたち (20 years old — special word for the age of majority).
How old are you? Telling ages in Japanese
Category: Counters
The Rule
歳 (or simplified 才) counts a person's age. Mostly regular: いっさい (1), にさい (2), さんさい (3)... Key irregular reading: 二十歳 = はたち (20 years old — special word for the age of majority). Sound change: 1 = いっさい, 8 = はっさい, 10 = じゅっさい.
Why This Matters
Asking and telling age is common in Japanese culture — it establishes the social hierarchy (senior/junior) that determines language register. While asking age can be rude in English-speaking cultures, it's more normalized in Japan, especially in work or educational settings. The special word はたち for 20 reflects the cultural importance of the coming-of-age milestone.
Examples
• おいくつですか？ — 三十五歳です。 — "How old are you? — I'm 35." [おいくつ = polite 'how old.' さんじゅうごさい = 35] • 娘は今年二十歳になります。 — "My daughter turns 20 this year." [二十歳 = はたち — the one irregular reading everyone must know] • 一歳の赤ちゃん — "A one-year-old baby" [いっさい = 1 year old (sound change)] • 何歳から学校に行きますか？ — "From what age do you go to school?" [何歳 = なんさい (how many years old)]
Common Mistakes
❌ にじゅうさい (for 20) ✅ はたち → While にじゅっさい is understood, the standard/cultural word for 20 years old is はたち. Using it shows cultural awareness ❌ いちさい ✅ いっさい → 1 year old: いち + さい → いっさい. Double consonant required, same pattern as いっぽん, いっぱい
Quick Tip
Japanese culture values knowing relative age — it determines who uses keigo to whom. If someone asks your age, it's usually to calibrate the relationship, not to judge. はたち (20) is culturally significant as the traditional age of adulthood.
Japanese culture values knowing relative age — it determines who uses keigo to whom. If someone asks your age, it's usually to calibrate the relationship, not to judge. はたち (20) is culturally significant as the traditional age of adulthood.
Examples
Common Mistakes
Incorrect: にじゅうさい (for 20) → Correct: はたち. While にじゅっさい is understood, the standard/cultural word for 20 years old is はたち. Using it shows cultural awareness
Incorrect: いちさい → Correct: いっさい. 1 year old: いち + さい → いっさい. Double consonant required, same pattern as いっぽん, いっぱい
Quiz
How do you say 'She just turned 20'?