Regional Guides
Korean Age System β Manuhori, Seoulnaai, and Yonnaai Explained
On June 28, 2023, Korea officially unified all legal and administrative ages around the international 'manuhori' (λ§ λμ΄) system. But Koreans in everyday life still mix in traditional 'sennaai' (μΈλ λμ΄) and the half-administrative 'yonnaai' (μ° λμ΄). Foreign residents and Korea-curious folks: here's the explainer.
Three age systems β one line each
**Manuhori (λ§ λμ΄)** β International age. You turn 1 on your first birthday. Now the legal standard in Korea.
**Sennaai (μΈλ λμ΄)** β Traditional Korean age. You're 1 at birth, +1 every January 1. Still common in casual conversation.
**Yonnaai (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 |
|---|---|---|
| Manuhori | 31 | Birthday passed β 31 |
| Sennaai | 32 | Born at 1 + add 1 every Jan 1 |
| Yonnaai | 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 |
|---|---|---|
| Manuhori | 30 | Birthday not yet |
| Sennaai | 32 | Same Jan 1 increment |
| Yonnaai | 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 (manuhori) age.
β Age Calculator
Which age do you use, when?
**Hospitals, government, legal documents**: Manuhori (since June 2023).
**Buying alcohol or tobacco**: Manuhori 19.
**Voting**: Manuhori 18 and over.
**Military service**: Mostly yonnaai, transitioning to manuhori.
**Schools**: Manuhori for enrollment, but classmates use yonnaai when talking to each other.
**Casual conversation, social media, self-introduction**: Any of the three. Older Koreans tend to prefer sennaai.
Frequently asked questions
What age should I tell foreign friends?
Manuhori β that's the international standard. 'I'm 30' means manuhori 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 manuhori and sennaai differ?
Up to 2 years. A baby born December 31 is sennaai 1 immediately, then 2 just one day later on January 1. The same baby is manuhori 0 until their first birthday.