For centuries, Koreans used a unique system of counting age — one that differs from most countries around the world.
In traditional Korean culture, a baby is considered 1 year old at birth, reflecting the time spent in the womb. Then, everyone's age increases by one on January 1st, regardless of their actual birthday.
So someone born on December 31st would be considered 2 years old the next day — despite being just a day old.
This system caused confusion in legal documents, healthcare, and international interactions. People had to write both their "Korean age" and "international age" on forms, which often led to miscommunication and errors.
In June 2023, South Korea officially abolished the traditional Korean age system in all legal documents. Now, only the international age (based on birthdate) is used for laws, contracts, and public services.
However, in everyday life, many Koreans still use the old system out of habit or cultural familiarity — especially when asking someone's age socially.
Despite the law change, there's still cultural value in understanding your Korean age. That's why we built the Korean Age Calculator — to help you find your age using both systems.