Korean Age Calculator

Korea has historically used three different ways of counting age at the same time, which is why one birth date can produce three different numbers. The calculator above shows all three.

• 세는 나이 (counting age) — the traditional “Korean age”. You are 1 at birth and everyone gains a year on January 1st, not on their birthday. Formula: current year − birth year + 1.
• 연 나이 (year age) — simply current year − birth year. It is used for military conscription, school entry, and age-rated media.
• 만 나이 (international or “full” age) — the same age used in the rest of the world, counted from your birthday. This is Korea's legal standard.

Because counting age adds a year at birth and another every January 1st, a baby born on December 31st is counted as 2 years old on January 1st — one day later.

On 28 June 2023, South Korea made international age (만 나이) the single standard for all legal and administrative purposes. Traditional counting age (세는 나이) no longer has legal force. The change was made to remove the ambiguity created by having several ages in circulation at once.

Year age (연 나이) was not abolished. It is still written into specific laws covering military service, school admission, and age restrictions on alcohol, tobacco, and media — so a Korean adult can still legitimately have two “official” ages depending on which statute applies.

In everyday conversation counting age remains common, especially among older generations, so many Koreans still know both numbers.

Age is particularly important in Korean culture because it determines:

• How you address others (formal vs. informal speech)
• Social hierarchy and relationships
• Military service timing for men
• School grade placement

Even with the official change to international age, these cultural aspects remain deeply ingrained in Korean society.