South Koreans have become a year or two younger as new laws that require using only the international method of counting age took effect, replacing the country's traditional method.
Under the age system most commonly used in South Koreans' everyday life, people are deemed to be a year old at birth and a year is added every 1 January.
A baby born on 31 December would be considered two-years-old on 1 January in Korean age.
The country has since the early 1960s used the international norm of calculating from zero at birth and adding a year on every birthday for medical and legal documents.
But many South Koreans continued to use the traditional method for everything else.
In December, South Korea passed laws to scrap the traditional method and fully adopt the international standard.
"We expect legal disputes, complaints and social confusion that have been caused over how to calculate ages will be greatly reduced," Minister of Government Legislation Lee Wan-kyu told a briefing on Monday.
According to a government survey conducted in September 2022, 86% of South Koreans said they would use the international age in their everyday life when the new laws took effect.
"I was about to turn 30 next year (under the traditional Korean age system) but now I have some more time earned and I love it," Choi Hyun-ji, a 27-year-old office worker in Seoul, said.
"It's just great to feel like getting younger," they added.
China, Japan, and even North Korea dropped the system decades ago but it has endured in the South, even as the land that gave the world K-pop and kimchi played a larger role on the international stage.
Some key areas, including the school year, eligibility for compulsory military service, and the legal drinking age, are determined by the other separate age system - known as "year age" - where a person's age is calculated from zero at birth and a year is added on 1 January.
Officials said that method would remain for the time being.
This means that, for example, everyone born in 2004 - whether January or December - is eligible to begin the military enlistment process from 1 January 2023, because they are all legally considered to have met the minimum required age of 19.
on 1 January in Korean age (Stock image)
"It's confusing when a foreigner asks me how old I am as I know they mean international age, so I have to do some calculations," office worker Hong Suk-min told AFP.
Mr Hong added, after a thoughtful pause, that he was 45 in international age and 47 under the Korean system.
The official change will have limited practical impact: many legal and administrative functions, including the age listed on a passport, the age at which one can be prosecuted as a juvenile, retirement benefits, or healthcare services, already uses date-of-birth rather than Korean age.
The government hopes the change will ease confusion and cites, for example, the issue of older Koreans who may believe they are eligible for pensions and free travel benefits several years before they legally are.
Complex calculation
"There is a difference between the age Koreans use in their daily lives and their legal age and because of that, various legal disputes may arise," Seoul's Minister of Government Legislation Lee Wan-kyu told AFP.
Mr Lee, who is overseeing the official age change, opened a media briefing on Monday by attempting to teach the assembled Korean journalists how to determine how old they are.
"Subtract your birth year from the current year. If your birthday has passed, that's how old you are, and if your birthday has not passed, subtract one to get your age," he said.
The government might consider revising the use of "year age" for such areas depending on how the current changes go, Mr Lee said.
'Age matters'
The idea behind "year age" is to ease South Korea's linguistic-linked hierarchies by ensuring that everyone in one school year is considered the same age and so can speak to each other without using honorifics.
"Age really matters" in South Korean culture, anthropologist Mo Hyun-joo told AFP, because it affects one's relative social status and dictates which titles and honorifics one must use for others.
"It's hard to communicate with people without knowing their age," she said.
People typically use terms such as "unni" and "oppa" - meaning older sister and older brother respectively - rather than names in conversation, she said.
South Korea's "hierarchical age-based culture (might) become neutralised a little" over time, Ms Mo said, because people become more used to using international age in school settings, for example.
For now most South Koreans, such as schoolboy Yoon Jae-ha from the southern port town of Busan, can simply enjoy feeling younger as the new legislation comes into effect.
"My age has shrunk," he said.
"I like being younger because then my mum will take care of me longer."
