Korean age explained

The three ways to count age

Here is how each system works. The examples assume someone born on May 10, 2000, on May 9, 2026.

• International age (만 나이, man-nai): you are 0 at birth and add a year on each birthday. This is how most of the world counts. Example: 25.
• Year age (연 나이, yeon-nai): the current year minus your birth year, regardless of your birthday. Everyone born in the same year is the same age. Example: 26.
• Counting age (세는 나이, se-neun-nai), often called "Korean age": you are 1 at birth and everyone adds a year on New Year's Day. It equals year age plus one. Example: 27.

Why counting age makes people older

Counting age starts at 1 instead of 0, and it adds a year to everyone at the turn of the year instead of on each birthday. A baby born on December 31 is 1 on that day and 2 the next morning, while in international age the same baby is 0 for its first full year.

Counting age is still heard in everyday conversation and in some traditions, such as celebrating 70th and 80th birthdays, but it has no role in Korean law.

What changed in June 2023

From June 28, 2023, Article 158 of the Civil Act and Article 7-2 of the Framework Act on Administration say that age is calculated in international age, counting the day of birth, and stated in years. Ages in laws, contracts, and official documents now mean international age even if they do not say so, unless a specific law sets a different rule.

According to the Ministry of Government Legislation, rules that already used international age, such as the age for receiving the national pension or the civil service retirement age, did not change. The reform made the default clear rather than changing how most legal ages were calculated.

Where year age still applies

A specific law can still choose another method. The best-known case is the Juvenile Protection Act. It defines a minor as someone under 19 but excludes anyone who has reached January 1 of the year they turn 19. So in Korea you can buy alcohol and tobacco from January 1 of the year you turn 19 in year age, regardless of your birthday.

When the 2023 reform took effect, the government also said that international age does not apply to the age for starting elementary school, military service obligations, or eligibility for civil service exams. Children start elementary school on March 1 of the year after the year they turn 6 in international age.

The government said it would review the remaining year-age rules, so they may change. For anything important, check the current law or ask the relevant agency.

A worked example

Someone born on December 31, 2007 reaches year age 19 on January 1, 2026, so they can legally buy alcohol in Korea from that day. In international age they are still 18 until December 31, 2026. In counting age they are 20 for all of 2026.

Someone born on February 29 has no birthday in common years. Under Article 160 of the Civil Act, a period whose final day does not exist ends on the last day of that month, so their year ends on February 28 and they can be treated as a year older from March 1. This site's calculator follows that rule.

Which age to give in Korea

At hospitals, banks, government offices, and on forms, give your international age. That is the default in law and what most official systems expect. If someone asks your age socially, they may still mean counting age, so it can help to say which one you mean.