Korean age is a traditional way of counting age. A baby is 1 year old at birth, and everyone gains a year on 1 January instead of on their birthday. The formula is simple: Korean age = current year − birth year + 1. Since 28 June 2023, South Korea uses international age, the system used in most of the world, for legal and official purposes.
The three ways age was counted in Korea
Before 2023, South Koreans could have three different ages at once.
System | Age at birth | Goes up on | Formula |
|---|---|---|---|
Traditional count | 1 | 1 January | current year − birth year + 1 |
Year age (yeon-nai) | 0 | 1 January | current year − birth year |
International age (man-nai) | 0 | your birthday | full years since birth |
The traditional count was the one people used in daily life. Year age was used by some laws, such as the rules for buying alcohol and tobacco and for military service. International age was already the legal standard for most purposes, a rule in place since 1962.
How to calculate Korean age
Take the current year.
Subtract the year you were born.
Add 1.
Your birthday plays no part. That is why the system could produce odd results. A baby born on 31 December was 1 on the day of birth and 2 the next morning, on 1 January, while only one day old.
To go the other way, from a traditional age to a birth year, subtract it from the current year and add 1. In 2026, someone who says they are 30 in Korean age was born in 1997.
Korean age by birth year in 2026
Born | Traditional count | International age |
|---|---|---|
1980 | 47 | 45 or 46 |
1985 | 42 | 40 or 41 |
1990 | 37 | 35 or 36 |
1995 | 32 | 30 or 31 |
2000 | 27 | 25 or 26 |
2005 | 22 | 20 or 21 |
2010 | 17 | 15 or 16 |
2015 | 12 | 10 or 11 |
2020 | 7 | 5 or 6 |
2025 | 2 | 0 or 1 |
The international age is the lower number until your 2026 birthday and the higher number after it.
Worked examples against international age
Born | Traditional count in 2026 | International age in 2026 |
|---|---|---|
31 December 2025 | 2 | 0 |
1 January 2010 | 17 | 16 |
15 March 1995 | 32 | 30 before 15 March, 31 after |
20 November 1985 | 42 | 40 before 20 November, 41 after |
The traditional count is always one or two years higher. It is two years higher between 1 January and the day before your birthday, and one year higher from your birthday to the end of the year.
What year age means
Year age sits between the other two. It starts at 0 and goes up every 1 January, so it is always one less than the traditional count. The rule for alcohol and tobacco is a good example. Wikipedia quotes it as: a person is allowed tobacco and alcohol "if it is after January 1 of the year one turns 19". So everyone born in the same year becomes eligible on the same day, whatever their birthday.
What changed in June 2023
South Korea's National Assembly passed a law on 8 December 2022 to stop the use of traditional ages on official documents. It took effect on 28 June 2023. The push came from President Yoon Suk Yeol's transition team in April 2022. The government said the aim was to end confusion and legal disputes over how to count age.
Overnight, most South Koreans became one or two years younger on paper. The Minister of Government Legislation, Lee Wan-kyu, said he expected that "legal disputes, complaints and social confusion" over age would be "greatly reduced".
Some rules still use year age. Wikipedia lists the year a child starts elementary school, buying alcohol and cigarettes, and eligibility for military service as areas that kept it.
Area | Age system after June 2023 |
|---|---|
Official documents and most laws | International age |
Alcohol and tobacco | Year age |
Starting elementary school | Year age |
Military service eligibility | Year age |
Do other countries use East Asian age?
The custom of counting age from 1 at birth was once common across East Asia. In the traditional Chinese version, a person was 1 at birth and turned 2 at the next Lunar New Year rather than on 1 January. Mainland China now uses birthdays for all official purposes. Japan abolished the old count by law in 1902 and passed another law in 1950 to encourage the modern system. In Vietnam, Wikipedia says the traditional count is still in limited use, mostly by older people in rural areas.
Curious which generation a birth year belongs to, whatever age system you use? The What Generation Am I? calculator works from the birth year alone. To find a birth year from an international age, use the Date of Birth Calculator.
How do I calculate my Korean age?
Subtract your birth year from the current year and add 1. Your birthday does not matter.
Is the traditional count still used?
Not for official purposes. Since 28 June 2023, South Korea uses international age on documents. Some people still mention the traditional count in daily life, and some rules use year age.
Why is Korean age older than real age?
Because a baby starts at 1 and everyone adds a year on 1 January, the traditional count is one or two years higher than international age.
What is year age in Korea?
Current year minus birth year, starting at 0. It is used for laws on alcohol, tobacco and military service.
How old is a baby born on 31 December under the old count?
1 at birth and 2 the next day, on 1 January.
What is my Korean age if I was born in 2000?
27 in 2026. Your international age is 25 before your 2026 birthday and 26 after it.
When did Korea switch to international age?
The law took effect on 28 June 2023.
What is man-nai?
The Korean name for international age, the count that starts at 0 and goes up on your birthday.
Sources
East Asian age reckoning, Wikipedia (the three systems, the 2022 law, remaining year-age rules, China, Japan and Vietnam)
'Korean age' abolished: how South Koreans became younger overnight, KTVU / FOX, June 2023 (effective date, minister's statement, 1962 standard)
