South Korea has been tallying age by birth dates since the 1960s. But while most East Asian countries have scrapped the traditional age-counting system, some have yet to follow suit.

In South Korea, “international age” refers to the number of years since a person was born, and starts at zero – the same system used in most other countries.

This traditional age counting method puts everyone as a year old at birth and adds a year to their age every Jan. 1 — even if they were born the day before.

In South Korea, “international age” refers to the number of years since a person was born, and starts at zero – the same system used in most other countries.