Ask a Korean how old they are and you may get a different number than your passport would give. Ask in 2020 and it would definitely have been different.
The system changed recently, and the change is not complete.
The traditional system
Under 세는나이 — "counting age" — you are 1 year old at birth, and everyone gains a year on January 1, not on their birthday.
The consequence is stark. A baby born on 31 December is 1 year old that day and 2 years old the next morning.
For everyone else, the gap from your international age is one or two years depending on whether your birthday has passed.
What changed in 2023
In June 2023, South Korea standardised on 만 나이 — international age — for legal and administrative purposes. Contracts, medical records, government documents, and legal ages now all use it.
The reason was practical: the country had been running three systems at once, including a third one used for military conscription and some legal purposes, and they produced different answers.
What did not change
Social usage. In conversation, many people still give their Korean age, especially when the question is really about seniority rather than about years.
The direction of travel is toward international age, and younger people increasingly use it by default. But you will still meet both, and asking which one someone means is completely normal:
- 만 나이로요? — In international age?
Why age matters so much
This is the part that surprises people. Age is not small talk in Korea. It determines how two people speak to each other.
Age decides:
- Which speech level you use
- What you call each other
- Who pays
- Who pours the drinks
The terms of address depend on both people's genders:
| Older man | Older woman | |
|---|---|---|
| Male speaker | 형 | 누나 |
| Female speaker | 오빠 | 언니 |
Someone the same age is 동갑, and that unlocks casual speech immediately — 동갑이네요! is a genuinely pleasant discovery in Korean conversation.
This is why the age question comes so early. It is not nosiness. It is a request for the information needed to speak to you correctly.
How to ask
- 몇 살이에요? — How old are you? (casual, for peers or younger)
- 나이가 어떻게 되세요? — More polite, for someone older or in a formal setting
- 연세가 어떻게 되세요? — Honorific, for elderly people
A gentler indirect route is the zodiac:
- 무슨 띠예요? — What's your zodiac animal?
The twelve-year cycle narrows someone's age without asking directly, and it is a common conversational move.
Answering
Age uses native Korean numbers with 살:
- 스무 살 — 20
- 스물다섯 살 — 25
- 서른 살 — 30
Remember that 스물 becomes 스무 before a counter.
You can also give your birth year, which is increasingly common and avoids the whole system question:
- 구십오 년생이에요. — I was born in '95.
~년생 is used constantly and is often more useful than the age itself, since it lets the other person calculate whatever they need.
빠른 년생
A historical complication worth knowing about. People born in January or February used to sometimes be grouped with the previous year's school cohort, which made them socially older than their birth year suggested.
It caused endless confusion and the practice was phased out. If someone mentions 빠른 년생, that is what they mean.
What to do as a foreigner
Give your international age. It is now the legal standard and is unambiguous. If someone converts it to Korean age in conversation, that is fine.
And expect the question early. It arrives faster than it would in most cultures, and it is not rude.
K-PATTO episodes include the ordinary conversations where this comes up — meeting people, working out how to address them, switching speech levels. The first ten are free at K-PATTO.