Korean Age Calculator
Someone born on 25 December 1990 is 35 in international age on 17 October 2026, 36 by year age and 37 by the old Korean counting age. Since 28 June 2023, South Korean law uses the first as the standard.
How to use
- Enter the birth date. The reference date starts as today, so change it to see a past or future date.
- Read your international age (만 나이), the old Korean counting age (세는 나이) and the year age (연 나이).
- Check the rows under the result for the years that Korean laws still count by year age, such as the school entry year and the year you stop being a minor for alcohol and tobacco.
How it works
International age (만 나이) is completed years: it goes up by one on each birthday and starts at 0 at birth. Old Korean counting age (세는 나이) is year age + 1: you are 1 at birth and add a year every 1 January. Year age (연 나이) is the reference year minus the birth year, so everyone born in the same year has the same age. For a birth on 25 December 1990 and a date of 17 October 2026: 2026 - 1990 = 36 year age, 37 counting age, and 35 international age because the birthday has not happened yet.
Counting age is one year above international age after your birthday and two years above before it. Born on 31 December, you are 1 at birth and 2 the next day by the old count.
Since 28 June 2023 the "unified international age" amendments to the Civil Act and the Administrative Framework Act make 만 나이 the standard way to count age in administration and civil matters, unless another law says otherwise. Several laws still count by year age: the Youth Protection Act treats people as youths until 1 January of the year they turn 19 (alcohol and tobacco), the Military Service Act uses the year you turn 18 and 19, and the Elementary and Secondary Education Act sets school entry by the year after turning 6. The tool shows those years from your birth year. Check the current text of each law for your case.
Three ages at a glance
| Age | Korean | Rule | Where used |
|---|---|---|---|
| International | 만 나이 | Completed years, +1 on birthday | Law and administration since 28 June 2023 |
| Counting | 세는 나이 | 1 at birth, +1 every 1 January | Informal; no longer the legal standard |
| Year | 연 나이 | Current year - birth year | Youth Protection Act, military service, school entry |
Sources
Ministry of Government Legislation (법제처): Administrative Framework Act Article 7-2 (행정에 관한 나이의 계산 및 표시) and Civil Act Article 158 (나이의 계산과 표시), as amended with effect from 28 June 2023.
Sources: Administrative Framework Act Art. 7-2 (Ministry of Government Legislation) · Civil Act Art. 158 (Ministry of Government Legislation)Last reviewed 2026-10-18
FAQ
Does Korea still use the Korean age system?
Officially no. Since 28 June 2023 the standard for law and administration is international age (만 나이). Many people still say the old counting age in casual talk, and a few laws such as alcohol and tobacco limits and military service use year age.
How do I convert Korean age to international age?
Subtract 1 if your birthday has passed this year, or 2 if it has not. For a fast check from year age: international age is year age if the birthday has passed, otherwise year age - 1.
What is year age (연 나이)?
Year age is the current year minus your birth year. It ignores the birthday, so two people born in the same year share it. It is still used for rules that apply to a whole birth-year group, like the legal drinking age.
How old is a baby in Korea?
Under international age a newborn is 0, and babies under one are usually described in months. By the old counting age a newborn was 1 and turned 2 on the next 1 January.
What about people born on 29 February?
In years with no 29 February, the tool counts the birthday as 28 February, the same month-end rule the Civil Act uses for periods that end on a missing date.