Korean Age Calculator (만 나이, 연 나이, 세는 나이)
Find your Korean ages from your birthday: international age (만 나이) used by law since June 2023, year age (연 나이) and traditional counting age (세는 나이).
연 나이 and 세는 나이 both go up on 1 January for everyone; 만 나이 goes up on your birthday.
| Birthday | Weekday | 만 나이 (turns) | 연 나이 that year | 세는 나이 that year |
|---|---|---|---|---|
| 2027-06-15 | Tuesday | 27 | 27 | 28 |
| 2028-06-15 | Thursday | 28 | 28 | 29 |
| 2029-06-15 | Friday | 29 | 29 | 30 |
| 2030-06-15 | Saturday | 30 | 30 | 31 |
| 2031-06-15 | Sunday | 31 | 31 | 32 |
Korea has used three ways to count age, which is why a Korean friend could be "two years older" in Seoul than abroad. This calculator gives all three from a date of birth: 만 나이 (international age, the legal standard since 28 June 2023), 연 나이 (year age, still used for military service and youth-protection rules) and 세는 나이 (traditional counting age), plus the days to your next birthday.
How to use this tool
- Enter the date of birth.
- Leave the reference date as today, or pick another day (for example an exam or contract date).
- Read the three ages and the countdown to the next birthday.
- Check the table to see how all three ages change on each coming birthday.
Formula
만 나이 = whole years since birth · 연 나이 = current year − birth year · 세는 나이 = 연 나이 + 1
International age goes up on each birthday. Year age and counting age both go up on 1 January for everyone born in the same year, so between 1 January and your birthday counting age is two more than international age, and after your birthday it is one more. A baby is 1 in counting age on the day of birth.
Example
Someone born on 31 December 2000 is, on 1 January 2026, 25 in international age (the birthday is still 364 days away), 26 in year age (2026 − 2000) and 27 in counting age. On 31 December 2026 they turn 26 internationally, while the other two ages stay at 26 and 27 until 1 January 2027.
Frequently asked questions
Which age is official in Korea now?
International age (만 나이). Amendments to the Civil Act and the Framework Act on Administrative Procedures that took effect on 28 June 2023 made it the default for laws, contracts and official documents unless a law says otherwise.
Where is 연 나이 still used?
Some laws keep counting by birth year, such as the Military Service Act (call-up age), the Youth Protection Act (buying alcohol and tobacco) and school entry, so everyone born in the same year is treated alike.
Why was counting age one at birth?
Traditional East Asian reckoning counts the year you are born in as your first year and adds a year at the Lunar or solar New Year rather than on birthdays. Many people still use it in conversation.
Sources
Last updated:
Page address with these inputs: https://kakao.mobile/tools/korean-age-calculator/
Cite or embed this tool
kakaoCalc. (2026, November 8). Korean Age Calculator (만 나이, 연 나이, 세는 나이). https://kakao.mobile/tools/korean-age-calculator/
“Korean Age Calculator (만 나이, 연 나이, 세는 나이).” kakaoCalc, 8 Nov. 2026, kakao.mobile/tools/korean-age-calculator/.
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