🎂 Korean Age Calculator
Enter your birthdate to instantly calculate your Korean age (만나이/man-nai), traditional counting age (세는나이), and year age. Based on Korea's 2023 Age Unification Act.
Man-nai (International / Legal Age)
-
years old
Man-nai (만나이)
-
yo
Counting Age (세는나이)
-
yo
Year Age (연나이)
-
yo
Next Birthday
-
📐 Formula
Man-nai (International Age) = Current Year - Birth Year - (1 if birthday not yet passed this year)
Counting Age (세는나이) = Current Year - Birth Year + 1
Year Age (연나이) = Current Year - Birth Year
* Since June 28, 2023, man-nai is Korea's official legal age standard.
💡 Examples
Example 1 – Birthday already passed (July 2026)
- Date of Birth
- March 15, 1990
- Man-nai
- 36 years (birthday passed in March)
- Counting Age
- 37 years
Example 2 – Birthday not yet passed (July 2026)
- Date of Birth
- December 25, 1990
- Man-nai
- 35 years (birthday not yet in 2026)
- Counting Age
- 37 years
❓ Frequently Asked Questions
Man-nai (만나이) is the international standard age calculation: you start at 0 at birth and gain 1 year on each birthday. Since June 2023, this is Korea's official legal age system, replacing the traditional counting age.
Traditional Korean counting age (세는나이) starts at 1 at birth (you're already "1" when born) and increases by 1 every January 1st, regardless of actual birthday. International age (man-nai) increases on your actual birthday, making Korean counting age typically 1-2 years higher.
Effective June 28, 2023, this law standardized all administrative and legal documents in South Korea to use man-nai (international age calculation), ending the decades-long confusion between the three different age systems.
If your birthday hasn't passed yet this year, your man-nai = current year - birth year - 1. For example, someone born December 1990 has man-nai of 35 in July 2026 (2026 - 1990 - 1 = 35).
Yes! Man-nai (만나이) is identical to the international age calculation used in most countries. It starts at 0 at birth and adds 1 year on each birthday — exactly as most of the world counts age.