Korean age calculator
Enter a date of birth for the international, year-based and traditional counted ages, plus the days to the next birthday.
Since 28 June 2023 Korean law counts age the international way — from your birthday. Three systems are still in use, though, because conscription, schooling and youth-protection law go by the year you were born. All three sit side by side here so you know which number a given office means.
Date of birth
What you enter is saved in this browser, so it is still here next time
Stored in this browser only — nothing is sent to a server
Left empty, this means today
The three ages
Enter a date of birth to see the ages.
Since 28 June 2023, Article 7-2 of the Framework Act on Administration and Article 158 of the Civil Act count age the international way. Unless a statute says otherwise, an age in Korean law, contracts and official papers means this one.
Some statutes still use year age — military service ages, school entry, and the definition of a youth under the Youth Protection Act. Each sets its own rule, which prevails over the general one.
Make a link with these numbers
Opening the link fills this screen with the same values. Useful for going through it with a partner, or for comparing two sets of conditions.
International age is counted by moving the birthday
First the birth year is subtracted from the reference year; then, if the birthday moved forward by that many years lands after the reference date, one is taken off. Someone born 15 May 1990 is 36 on 4 September 2026 and 35 on 14 May 2026, the birthday not yet having come round. Because the birthday is moved rather than month and day being compared, 29 February needs no special case — when the moved date does not exist it folds to the last day of that month, so in a common year the age rises on 28 February. In a leap year such as 2028, 29 February is the birthday as normal.
Year age and counted age look only at the year
Year age is reference year minus birth year, and counted age is that plus one. Neither looks at the birthday, so both change on 1 January. Someone born 31 December 2000 is 0 international, 1 year age and 2 counted on 1 January 2001. Everyone born in the same year shares a year age wherever their birthday falls, which is why conscription and school entry, which group people by cohort, use it. The page shows all three side by side with a short note on where each applies.
Next birthday, adulthood and zodiac sign
The next birthday is the first date on or after the reference date reached by adding 12 months at a time to the birth date; if the reference date is the birthday itself, the days remaining are 0 and it says "today". Days lived counts from birth to the reference date. The date of adulthood is the birth date plus 19 years — age 19 as set by Article 4 of the Civil Act. The zodiac animal is taken from that year's Lunar New Year rather than the solar year: a birth before New Year's Day gets the previous year's animal, and the reason is stated. Outside 1900–2050, which the New Year table covers, no zodiac row is shown.
Changing the reference date
Leave the reference date blank and it is today. Enter a specific day — a start date, an exam date, a contract date — and the three ages are given for that day, so a condition like "international age on the exam date" can be checked directly. A reference date before the birth date means the person is not yet born, and no answer is given. Dates entered stay in this browser and go to no server. Fortune-telling uses the start of spring rather than Lunar New Year as the year boundary and differs by a few days; this page uses Lunar New Year only.
Common questions
QHow do the three ages differ?
International age goes up on your birthday. Year age is simply this year minus your birth year, so it changes on 1 January regardless of birthday. The traditional counted age starts at one on the day you are born and adds a year each New Year — someone born on 31 December is two the next day.
QDoes anything still use year age?
Yes. Military service ages under the Military Service Act, school entry under the Elementary and Secondary Education Act, and the definition of a youth under the Youth Protection Act (year age under 19). Those statutes set their own rule, which prevails over the general one.
QWhat about people born on 29 February?
In a common year their age rises on 28 February. Article 160(3) of the Civil Act says a period expires on the last day of the month when the matching date does not exist, so 28 February stands in for the missing 29th. Some read that as the end of the 28th, hence 1 March; this page follows the wording and adds the year on the 28th. In a leap year it is 29 February as usual.
QHow old is someone born in 2000 in 2026?
International age is 25 before the birthday and 26 after it. Year age is 2026 − 2000 = 26 all year, and counted age is 27. A condition such as "26 or under" gives a different answer depending on which age it means, so check the rule that applies.
QWhen does someone turn 19?
On the birth date plus 19 years — the nineteenth birthday. Someone born 4 September 2007 turns 19 on 4 September 2026 and is an adult under the Civil Act from that day. The "adult on" row shows this date with its weekday.