Most people assume that age is calculated the same way everywhere in the world. In reality, different cultures have used remarkably different systems throughout history — and some may surprise you considerably. Here's a world tour of how age has been, and still is, measured differently depending on where you're from.
In most Western countries including the UK, USA, Australia and Europe, age is counted from the moment of birth. You are zero years old until your first birthday, when you turn one. This is the most widely used system internationally, and the one recognised on virtually all legal documents worldwide, including passports and visas.
In traditional Korean, Chinese and Vietnamese cultures, a baby is considered to be one year old at birth. The time spent in the womb counts as the first year of life. This means a baby born in this tradition is already "one" on their actual day of birth, and turns "two" at the next Lunar New Year — regardless of how many actual months old they are.
In South Korea, this traditional system was officially used in everyday and even some official contexts for generations. In June 2023, the South Korean government formally standardised the international Western age system for all legal and administrative purposes — meaning contracts, medical records, and official documents now use the Western count exclusively, even though many Koreans still casually refer to their traditional age in social settings.
Japan historically used a system called kazoedoshi, where everyone became one year older on New Year's Day regardless of their actual birthday. This meant two people born on December 31st and January 1st could be the same age for most of the year but differ by two kazoedoshi years immediately after New Year. This system is now rarely used in modern Japan, having been officially replaced by the Western system in 1950, though it survives in some traditional and religious contexts.
In parts of India, particularly in traditional and religious contexts, age can also be counted using the Hindu lunar calendar, which affects when certain birthdays and coming-of-age ceremonies are observed. While official Indian documents use the standard Western system, many families still calculate significant life events using lunar or astrological calendars alongside it.
Ethiopia uses its own calendar, which runs roughly 7 to 8 years behind the widely used Gregorian calendar due to a different calculation of Jesus's birth year. This means a person's "Ethiopian age" in years can differ noticeably from their internationally recognised age, even though the actual amount of time they've lived is identical — it's simply a different counting system, not a different reality.
| System | Age at Birth | When Age Increases |
|---|---|---|
| Western | 0 | On your birthday |
| Traditional East Asian | 1 | Varies by culture (birthday or Lunar New Year) |
| Japanese Kazoedoshi | 1 or 2 | New Year's Day for everyone |
| South Korea (since 2023) | 0 | On your birthday (Western, now legally standard) |
Our Age Calculator uses the internationally recognised Western system, giving you the most widely accepted and legally accurate age for official use anywhere in the world — passports, visas, school admissions, and legal documents all rely on this standard.
As of June 2023, South Korea officially uses the Western age system for all legal and administrative purposes. However, many Koreans still informally reference their traditional age in casual conversation.
Kazoedoshi is a traditional Japanese age-counting system where everyone's age increased by one on New Year's Day, rather than on their individual birthday. It was officially replaced by the Western system in 1950.
In traditional East Asian systems, time spent in the womb is counted as part of a person's age, so a baby is considered to already be one year old on the day they are born, rather than zero.
For passports, visas, school admissions, and virtually all international legal purposes, the Western age system (counting from zero at birth, increasing on your birthday) is the globally recognised standard.
Use our free Age Calculator to instantly find your exact age in years, months, and days using the internationally recognised standard.