Why is Korean age different?
If a Korean person tells you they're 25 but their passport says 23, they're not lying — Korea has historically used up to three different ways of counting age at the same time. Here's the quick version.
1. Counting age — 세는 나이
This is the traditional "Korean age" everyone means when they say Korean age. The rules are simple: you're 1 year old the day you're born, and everyone turns a year older together on January 1st — not on their birthday. The formula is:
- Counting age = current year − birth year + 1
So a baby born on December 31st is "2 years old" just one day later, on January 1st. This is why Korean age is usually 1 or 2 years higher than what you're used to.
2. Year age — 연 나이
A simpler middle-ground used for laws based on the calendar year — like which school grade you're in, when you do military service, and the legal age to drink or smoke. The formula drops the "+1":
- Year age = current year − birth year
3. International age — 만 나이
This is the age you already know: you start at 0 and gain a year on your actual birthday. Since June 2023, South Korea has officially adopted international age for all legal, medical, and administrative purposes — so on paper, everyone in Korea got "younger." In casual conversation, though, the traditional counting age still pops up all the time.
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Age in Korean uses Native Korean numbers followed by the counter 살 (sal). For example:
- 20 years old → 스무 살 (seumu sal) — note 20 alone becomes 스무, not 스물
- 25 years old → 스물다섯 살 (seumul-daseot sal)
- 30 years old → 서른 살 (seoreun sal)
The calculator above shows your counting age spoken in Korean automatically. Want the full breakdown of both Korean number systems? Read our guide to Korean numbers: Sino vs Native, then grab the 20 essential Korean phrases to start introducing yourself. And since your Korean age is tied to your birth year, find out your Korean zodiac animal (띠) too.
Frequently asked questions
How is Korean age calculated?
Traditional Korean age (counting age) = current year − birth year + 1. You're considered 1 at birth and everyone ages together on January 1st, so it's usually 1–2 years higher than your international age.
Does Korea still use Korean age in 2026?
Officially, no — since June 2023 all legal and medical matters use international age. But the traditional counting age is still common in everyday speech, and year age is still used for school, military service, and legal age limits.
What's the difference between counting age and year age?
Counting age adds +1 (starts at 1 at birth); year age doesn't (current year − birth year). International age is your real age based on whether your birthday has passed this year.
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