Regional Guides
Korean Age β Man-nai, Se-neun-nai and Yeon-nai Explained
On June 28, 2023, Korea officially unified all legal and administrative ages around the international 'man-nai' (λ§ λμ΄) system. But Koreans in everyday life still mix in traditional 'se-neun-nai' (μΈλ λμ΄) and the half-administrative 'yeon-nai' (μ° λμ΄). Foreign residents and Korea-curious folks: here's the explainer.
Three age systems β one line each
**Man-nai (λ§ λμ΄)** β International age. You turn 1 on your first birthday. Now the legal standard in Korea.
**Se-neun-nai (μΈλ λμ΄)** β Traditional Korean age. You're 1 at birth, +1 every January 1. Still common in casual conversation.
**Yeon-nai (μ° λμ΄)** β 'Current year minus birth year'. Used for some administrative things like school grade and (partially) military service.
Example β born May 1, 1995, viewed on May 8, 2026
Birthday has passed for the year, so differences are minimal.
| Age type | Value | Calculation |
|---|---|---|
| Man-nai | 31 | Birthday passed β 31 |
| Se-neun-nai | 32 | Born at 1 + add 1 every Jan 1 |
| Yeon-nai | 31 | 2026 β 1995 = 31 |
Example β born December 1, 1995, viewed on May 8, 2026
Birthday hasn't passed this year, so the gap is larger.
| Age type | Value | Calculation |
|---|---|---|
| Man-nai | 30 | Birthday not yet |
| Se-neun-nai | 32 | Same Jan 1 increment |
| Yeon-nai | 31 | 2026 β 1995 = 31 |
Calculate your Korean age
Enter your birthdate to see all three Korean age types side by side, plus the international (man-nai) age.
Age CalculatorWhich age do you use, when?
**Hospitals, government, legal documents**: Man-nai (since June 2023).
**Buying alcohol or tobacco**: Man-nai 19.
**Voting**: Man-nai 18 and over.
**Military service**: Mostly yeon-nai, transitioning to man-nai.
**Schools**: Man-nai for enrollment, but classmates use yeon-nai when talking to each other.
**Casual conversation, social media, self-introduction**: Any of the three. Older Koreans tend to prefer se-neun-nai.
Frequently asked questions
What age should I tell foreign friends?
Man-nai β that's the international standard. 'I'm 30' means man-nai 30.
Why did Korea use a different system at all?
East Asian tradition; China and Japan used similar systems historically. Japan abolished it in 1902, China by the 1960s. Korea kept it officially until June 2023.
How much can man-nai and se-neun-nai differ?
Up to 2 years. A baby born December 31 is se-neun-nai 1 immediately, then 2 just one day later on January 1. The same baby is man-nai 0 until their first birthday.
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