Talking About Age and Generations in Japanese

The sai counter and the readings that trip people up

Age uses the counter sai, written 歳 in formal contexts and often simplified to 才 on forms and shop signs. It attaches to the Sino-Japanese numbers, so most ages are completely predictable: nisai, sansai, yonsai, gosai, rokusai, nanasai, kyūsai. The counters guide covers how this fits into the wider counter system; here you only need the three irregulars and the one exception.

The irregular points are one, eight and ten. Issai, hassai and jussai all shorten the number and double the s. Because compounds inherit the pattern, every decade boundary is irregular too: sanjussai, yonjussai, gojussai. You will also hear jissai instead of jussai from older speakers and in careful announcements, and both are correct.

Hatachi and why twenty is different

Twenty is the one age that abandons the counter. In speech a twenty-year-old is hatachi, and you say hatachi desu with no sai attached. The regular form nijussai is not wrong, and you will see it in documents, medical intake and news writing, but using it about yourself in conversation sounds like reading from a form.

Hatachi carries a social weight beyond the number, because twenty has long been the age of adulthood in Japan and is still the age most people associate with the coming-of-age ceremony. The legal age of majority has been revised in recent years, so avoid stating rules about what a twenty-year-old may do and describe the ceremony instead.

Asking someone's age politely

There are three registers. Nansai desu ka is neutral and completely normal toward a child. O-ikutsu desu ka is the polite adult version, using the honorific o and the softer ikutsu, and it is what you should reach for with anyone you do not know well. Toshi wa is casual and belongs among friends of a similar age.

Whichever you choose, an adult question is usually cushioned. Shitsurei desu ga means excuse me for asking, and kiite mo ii desu ka asks permission before the question lands. If the other person deflects with himitsu desu or a laugh, take the answer and move on without repeating it.

Answering about your own age

The plain answer is your number plus sai desu, and adding ni narimashita for a recent birthday makes it sound more like conversation than data. If you would rather not give the exact number, the decade answer is completely normal and not evasive: sanjūdai desu closes the question politely.

Two useful softeners are mō and mada. Mō sanjussai desu means I am already thirty, with a note of surprise at yourself, while mada nijūdai desu means I am still in my twenties. Learners often produce a flat number and miss the small feeling that a Japanese speaker would add.

Decades and generation words

The suffix dai after a round decade names the whole band, so jūdai is teenagers, nijūdai is people in their twenties, and rokujūdai is people in their sixties. Add zenhan, nakaba or kōhan to narrow it to the early, middle or late part. In casual speech you will also hear the borrowed set arasā and arafō, meaning around thirty and around forty, which are conversational and slightly playful rather than neutral.

Sedai means generation and appears in dōsedai, someone of your own generation, and in named cohorts such as dankai no sedai, yutori sedai and zetto sedai. Use named cohorts carefully, since they carry opinions attached; dōsedai is the safe, friendly word for shared references.

Hayaumare is worth knowing because Japanese school years start in April. Someone born in February is in the school year above the person born the following May, so two people the same age on paper can be a year apart at school, and that difference can still shape how they speak to each other years later.

Milestone ages and how they are marked

Several ages have their own celebrations. Shichi-go-san is a family visit to a shrine for children around three, five and seven, and families usually dress up and take photographs. Seijinshiki is the coming-of-age ceremony held in January for young adults, with formal clothing and a local ceremony. Practice varies by region and family, and plenty of people skip these entirely.

Later milestones have names taken from written characters. Kanreki at sixty marks a full cycle of the traditional calendar and is often celebrated with red items. Koki is seventy, kiju seventy-seven, beiju eighty-eight and hakuju ninety-nine. You do not need to produce these words, but recognising them helps when a colleague mentions a family party.

Age on forms and applications

Paperwork uses a small fixed vocabulary. Nenrei is the field labelled age, seinengappi is date of birth, and man-nenrei is your age counted the ordinary way, from your birthday. The older system kazoedoshi counted everyone up one at new year and now appears mainly in traditional contexts, so if a form says man, write the age you would say aloud.

Conditions are written with ijō for and above and miman for under, as in man-jūhassai ijō. Rules and thresholds change, so read the form rather than assuming, and ask the counter staff if the wording is unclear. The city hall procedures guide covers the wider paperwork conversation.

A child's age in years and months

For babies and toddlers, months matter more than years. Before the first birthday you say seigo plus the months, as in seigo rokkagetsu, six months old. After that the pattern is years plus months: issai sankagetsu is one year and three months. Han for half is very common in speech, so nisai han is two and a half.

The question is nankagetsu desu ka for months and nansai desu ka for years. A parent will often answer with both, and the small talk that follows is predictable enough to rehearse: kawaii desu ne, genki desu ne, and a comment about how fast they grow.

Age, senpai and how it changes your speech

Age in Japanese is not only information; it sets the default register. A person even a year toshiue is often addressed more politely, and the senpai and kōhai relationship at school and work is built on entry order, which usually tracks age. The dedicated senpai and kōhai post covers that hierarchy in detail, so here the point is narrower: knowing the age gap tells you whether to keep desu and masu or to relax.

The move to casual speech is negotiated, not assumed. Tameguchi de ii desu yo invites the other person to drop polite forms, and it is normally offered by the older or more senior person. Until it is offered, stay polite, even with someone your own age, and keep san on their name. The polite versus casual guide explains the forms themselves.

Notice keigo ja nakute mo ii desu yo in the fifth row: the full form includes mo, and dropping it changes the sentence. Learners often hear the shortened casual version and reproduce it without mo, which sounds abrupt when said to someone you have just met.

Drills that make age vocabulary automatic

• Say the four broken forms every morning until they are reflexes: issai, hassai, jussai, hatachi.
• Count your family aloud with sai, then say the same list again with dai bands instead of exact numbers.
• Rehearse both halves of the exchange: shitsurei desu ga, o-ikutsu desu ka, and your own answer straight after.
• Practise one deflection you are comfortable with, such as sanjūdai desu, so a sensitive question never leaves you silent.
• Read any Japanese form you already have and say the nenrei and seinengappi fields out loud.
• Whenever you learn a new person's age in real life, say the toshiue or toshishita sentence about them in your head.