Age & D-Day Calculator
Get your international age and next birthday from a date of birth, or the days between two dates.
About this tool
Korea counts age in three ways. International age, which increases on your birthday, has been the legal and administrative default since 2023. Calendar-year age is the current year minus your birth year, and it is the basis used by the Youth Protection Act and the Military Service Act. Korean traditional age counts the year of birth as one. Enter a date of birth and this tool shows all three side by side.
It also gives the days remaining until your next birthday and the total number of days you have been alive. Since international age changes on the birthday itself, whether this year’s birthday has passed is what determines the answer.
The D-Day tab counts the days between two dates. Alongside the total it gives the number of weekdays, which is useful for planning against working days. Note that the weekday count excludes only Saturdays and Sundays and takes no account of public holidays — check the holiday calendar alongside it if those matter.