On June 28, 2023, South Korea made international age the standard for legal and administrative purposes. The National Assembly passed the changes in December 2022. Overnight, most South Koreans became 1 or 2 years “younger” on paper.
The 3 ways of counting age in Korea
| System | Korean name | At birth | Goes up on |
|---|---|---|---|
| Korean age | 세는 나이 | 1 | January 1 |
| International age | 만 나이 | 0 | Your birthday |
| Year age | 연 나이 | 0 | January 1 |
Korean age counts the year of life you are in, so a newborn is 1. International age counts finished years, as in most of the world.
What the law changed
Contracts, official documents and public services now use international age unless a law says otherwise. Before the change, everyday conversation used Korean age, many laws used year age and medical and legal documents used international age, which caused confusion and disputes.
What still uses year age
A few areas kept year age after June 2023, including conscription, school entry and the legal ages for buying alcohol and tobacco. Under year age, everyone born in the same year crosses the line together on January 1. In 2026, that means people born in 2007 or earlier can buy alcohol and tobacco.
A worked example
Jungkook of BTS was born on September 1, 1997. On August 31, 2026 his ages are:
- Korean age: 2026 − 1997 + 1 = 30
- International age: 28 (his birthday is the next day)
- Year age: 2026 − 1997 = 29
The Korean Age Calculator gives all 3 for any date of birth and any date, and works in reverse from a Korean age.
