Why you might be one year older than your birth certificate suggests
In short: In many East Asian cultures, you don't start life at zero. Instead, you begin your journey already one year old. This traditional method of counting years isn''t just a quirk of arithmetic; it is a system deeply rooted in ancient astrology and the movement of the stars.
Traditional East Asian age reckoning, practiced historically across China, Japan, Korea, and Vietnam, operates on a different logic than the international system. Rather than counting the number of years elapsed since birth, this method counts the number of calendar years—or specifically, the number of Jovian stars—a person has lived through. Under this system, a newborn is immediately considered one year old, and their age increases with each New Year.
The origins of this practice lie in ancient Chinese astrology. The system was tied to the belief that human fate is bound to stars positioned in opposition to Jupiter. This duodecennial cycle, which also informs the 12 animals of the zodiac, became widespread throughout the Sinosphere by the Song dynasty. Because the age increments on New Year's Day rather than a birthday, a child born on December 31 could technically become two years old on January 1.
As modern legal standards have shifted, many nations have moved toward the international system to reduce social confusion. Japan officially transitioned via the Meiji Reforms and later laws in 1902 and 1950. North Korea eliminated its traditional system in the 1980s. Most notably, South Korea formally switched to the international system on June 28, 2023, following intense debate sparked by the COVID-19 pandemic. This change aimed to resolve discrepancies in vaccine eligibility and reduce age-based social hierarchies.
Despite these legal shifts, traces of the old ways remain. In Taiwan, traditional ages are still widely used in various social contexts. In Vietnam, the practice survives among older generations in rural areas, often referred to as 'midwives’ age.' Even in mainland China, where official documents use the international system, the linguistic term 'suì' remains the standard way to discuss age.
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- Summary by Intellect · source: East Asian age reckoning
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