Korean age calculator

The shortcut is add one if your birthday has already passed this year, add two if it has not. This converts an international age to the traditional Korean age.

Korean age starts at one at birth. Everyone gains a year on 1 January, regardless of their birthday.

If you are 21 today and have already had your birthday this year, your Korean age is 22. If you are 21 and your birthday is still ahead, it is 23. These are two possible birth years for someone who is currently 21.

This is also why a December baby is two years old in Korean age within weeks. Born in late December, they are one; on 1 January they turn two.

International age (만 나이) starts at zero at birth and increases by one on each birthday. Since June 2023 this is the legal default in Korea, including contracts, medical records, pensions and benefits unless a specific rule states otherwise.

Korean age (세는 나이) starts at one the day you are born and adds a year every 1 January. Your birthday has nothing to do with it. It is one or two years higher than your international age, and is used in conversation.

Year age (연 나이) is simply this year minus your birth year. It is used in the two laws explained below.

The difference between Korean age and international age is one or two years. From your birthday to 31 December it is one. From 1 January to the day before your birthday it is two. If your current international age is 30, your Korean age is 31 if your birthday has arrived this year, or 32 if it is still ahead. Your Korean age stays the same on your birthday; your international age increases. Year age never moves within a year at all: it is one above your international age before your birthday and equal to it after.

American age means international age here. In the United States, age starts at zero at birth and increases on each birthday. Add one or two to convert it to Korean age.

Korean age starts at one and increases on New Year’s Day, even if only a few days have passed since birth.

Take someone born on 31 December. They are one year old on the day they are born, and two years old the next morning. One day lived, two years old in Korean age. Their international age is zero.

Giving your birth year avoids ambiguity about whether you mean international age, year age or traditional Korean age.

On 28 June 2023 Korea unified legal and administrative age on the international system. Previously, different forms could use different age systems for the same person.

What changed is the default reading. When a law states an age without saying which system, it now means international age. For almost everything official, international age is the only number you need.

Traditional Korean age remains in conversation, including how people address someone older.

Two laws kept the old system: the Youth Protection Act and the Military Service Act. Both go by birth year and ignore your birthday.

The threshold is year age 19. In 2026, people born in 2007 reach that threshold on 1 January, regardless of their birthday.

Starting primary school and military examination notices work the same way, off the birth year. Use the year-age column for these comparisons.

If it is a form, a hospital or a contract, give your international age. That is what the paperwork expects.

If it is a person, the easiest answer is your birth year — “I was born in 1993.” This avoids ambiguity about the age system.

You can also convert Korean housing measurements with the pyeong calculator.