Traditionally Koreans were one year old at birth and everyone gained a year on New Year’s Day, so a baby born in December could be “two” days later. Since 28 June 2023 South Korea uses international age in law and official documents, but the traditional age is still widely used socially. “Year age” is used for things like military service and the legal drinking age.
How to use the Korean Age Calculator
- Date of birth
- Date
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter your date of birth and the date to compare (today by default).
Tips
- Check whether the end date should be included – event durations usually include it, elapsed time does not.
- Months have 28–31 days, so “one month” is counted by calendar date, not as 30 days.
- Use 24-hour time or set AM/PM carefully when entering clock times.
- Time zones and daylight-saving changes are not applied unless the calculator says so.
Common mistakes to avoid
- Counting a 30-day month when a calendar month is meant (or the reverse).
- Forgetting leap years when counting days across February.
- Mixing decimal hours (7.5 h) with clock time (7:30).
Inputs explained
| Field | What to enter |
|---|---|
| Date of birth | A date |
| Date | A date |
What each result means
- Korean age (traditional) = year([Date]) – year([Date of birth]) + 1
- Year age (연 나이) = year([Date]) – year([Date of birth])
- International age (만 나이) = floor(monthsbetween([Date of birth], [Date])÷12)
- Korean minus international = [Korean age (traditional)] – [International age (만 나이)]
Formula
Korean (counting) age = current year − birth year + 1Year age (연 나이) = current year − birth yearInternational age = full years since birthWorked example
Inputs — Date of birth: 2000-12-30; Date: 2026-10-25.
Results — Korean age (traditional) = 27 years; Year age (연 나이) = 26 years; International age (만 나이) = 25 years; Korean minus international = 2.
Frequently asked questions
How do I calculate my Korean age?
Current year − birth year + 1.
Does South Korea still use Korean age?
Officially no – since June 2023 laws use international age, but the traditional count is still common socially.
Why can Korean age be 2 years higher?
You are counted as 1 at birth and gain a year every 1 January, before your birthday.
What formula does the Korean Age Calculator use?
Korean (counting) age = current year − birth year + 1.