How to Say Age in Japanese - The Sai Counter
The Japanese age counter is 歳 (sai), often written 才 in casual contexts. The pattern is regular at most positions but irregular at 1, 8, 10, and especially 20 (hatachi). This page covers the full table, the etiquette of asking ages, and the cultural significance of 20.
The 〜歳 (sai) counter
To express age, attach 〜歳 to the number: [number] + 歳 + です = "I am [number] years old". Two kanji are common: 歳 (traditional, formal) and 才 (simplified, very common in writing for under-13). 才 is technically a different kanji meaning "talent" but functions as an ateji for sai.
Selected ages with irregular readings
| Age | Romaji | Notes |
|---|---|---|
| 1 | is-sai | irregular |
| 2 | ni-sai | |
| 3 | san-sai | |
| 4 | yon-sai | |
| 5 | go-sai | |
| 6 | roku-sai | |
| 7 | nana-sai | |
| 8 | has-sai | irregular |
| 9 | kyū-sai | |
| 10 | jus-sai (or jis-sai) | irregular |
| 11 | jū-is-sai | irregular |
| 12 | jū-ni-sai | |
| 18 | jū-has-sai | irregular |
| 20 | hatachi | totally irregular - special word |
| 21 | ni-jū-is-sai | irregular |
| 25 | ni-jū-go-sai | |
| 30 | san-jus-sai | irregular |
| 40 | yon-jus-sai | irregular |
| 50 | go-jus-sai | irregular |
| 60 | roku-jus-sai | irregular |
| 70 | nana-jus-sai | irregular |
| 80 | hachi-jus-sai | irregular |
| 90 | kyū-jus-sai | irregular |
| 100 | hyaku-sai |
Asking age politely
- Casual: 何歳ですか (nan-sai desu ka), "how old are you?"
- Polite: おいくつですか (o-ikutsu desu ka), more polite. Used with strangers, customers, in formal settings.
- Best avoided: 何歳 with elders or in business. It can read as blunt.
Saying your own age
- 私は二十五歳です (watashi wa ni-jū-go-sai desu) - "I am 25 years old".
- 二十五です (ni-jū-go desu) - very casual, dropping the counter.
- Children often write 私は5才 (watashi wa go-sai) using 才.
Age-related vocabulary
- 誕生日 (tanjōbi) - birthday
- 年齢 (nenrei) - age (formal noun)
- 年 (toshi) - year, age (in some compounds)
Cultural note on counting age: traditional East Asian "year-counting" added a year at New Year, so a baby was already "1" at birth. Modern Japan officially uses Western age-counting (you turn 1 at your first birthday). The traditional system survives only in some festivals and astrology.
Frequently asked questions
What does hatachi mean?
Hatachi (二十歳) means "20 years old". It is a special, totally irregular word, not a regular ni-jū-sai construction. 20 was historically the age of legal adulthood in Japan (changed to 18 in April 2022, though hatachi remains the celebratory milestone). Coming-of-age day, 成人の日 (seijin-no-hi), celebrates 20-year-olds.
How do I ask someone’s age in Japanese politely?
何歳ですか (nan-sai desu ka) is direct. For polite contexts, especially with strangers, customers, or older people, おいくつですか (o-ikutsu desu ka) is preferred. It literally means "how many" but functions as a polite age question. Avoid 何歳 with elders or in business unless the relationship is informal.
What is the difference between 歳 and 才?
Both are read sai. 歳 is the traditional, formal kanji. 才 is a simplified ateji (originally meaning "talent") that has been adopted for sai because it is much easier to write. 才 is very common in everyday writing, especially for ages under 13 or in children’s contexts. Tax forms and formal documents prefer 歳.
Why are 1, 8, 10, 20 sai irregular?
Sound-changes. 1 (is-sai) and 8 (has-sai) take gemination, the same pattern that produces ip-pon and hap-pon in other counters. 10 takes jus-sai (or the older jis-sai). 20 has the unique hatachi, preserved from native Japanese. The irregulars are memorised, not derived.
Continue: counters hub · reading variations · numbers 1 to 100.