Lunar Age Calculator (East Asian Age)

Calculate traditional East Asian "lunar" age, where you are one year old at birth and gain a year each new year.

Result

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How to use this calculator

Enter your birth date.
Leave the current date as today or set a specific date.
Read your traditional East Asian (lunar) age and your international age.
Near Lunar New Year, expect the traditional figure to vary by one depending on the exact reckoning.

About this calculator

In traditional East Asian age reckoning — historically used in China, Korea, Japan, and Vietnam — a baby is considered one year old at birth, and everyone adds a year together at the start of the new year rather than on their individual birthday. As a result this "lunar age" (sometimes called nominal or Korean age) is typically one to two years higher than the international age used elsewhere. This calculator computes the traditional age using the common approximation of the current calendar year minus the birth year plus one, alongside your international age for comparison. Note two subtleties: the most traditional version adds the year at Lunar New Year (which falls in late January or February), not on January 1, so the value can be off by one near that date; and South Korea officially adopted international age in June 2023 for most purposes.

How it works — the formula

East Asian age ≈ Current year − Birth year + 1
International age = completed years since birth

Traditional reckoning starts at one and increments at the new year; the international system starts at zero and increments on the birthday.

Source: Wikipedia — East Asian age reckoning

Worked examples

Example 1

Born 1990, in 2026

Inputs:: birth=1990-06-15, today=2026-05-21
Output:: lunar 37; international 35

Example 2

Born 2000, in 2026

Inputs:: birth=2000-01-01, today=2026-05-21
Output:: lunar 27; international 26

Example 3

Born 2026, in 2026

Inputs:: birth=2026-01-01, today=2026-05-21
Output:: lunar 1; international 0

Limitations

Uses the calendar-year approximation, not the exact Lunar New Year.
Variants (counting from conception) differ slightly.
South Korea now uses international age legally (since June 2023).

Cultural age-reckoning tool; the calendar-year approximation may differ by one near Lunar New Year.

Frequently asked

What is East Asian or "lunar" age?+

It is a traditional way of counting age in which a newborn is one year old at birth and everyone gains a year at the new year, rather than on their birthday. It typically runs one to two years ahead of the international age.

How is lunar age calculated?+

The common approximation is current year − birth year + 1. So someone born in 1990 is 2026 − 1990 + 1 = 37 in 2026 by traditional reckoning, even though their international age may be 35 or 36.

Why is it one to two years higher than my real age?+

Two effects stack: you start at age one (not zero) at birth, and you add a year at the new year rather than on your birthday. Before your birthday in a given year, you can be two years "older" in traditional age than international age.

Does the year change on January 1 or Lunar New Year?+

Traditionally at Lunar New Year (late January or February), though a calendar-year approximation using January 1 is common and is what this tool uses. Around Lunar New Year the two methods can differ by a year.

Is lunar age still used?+

It remains culturally familiar in parts of East Asia, but official use has declined. South Korea passed a law effective June 2023 standardizing on international age for legal and administrative purposes, though traditional age persists in everyday conversation.

What is the difference between Korean age and lunar age?+

"Korean age" usually refers to this same traditional system (one at birth, +1 each new year). Some variants count from conception or use slightly different new-year timing, but the everyday Korean age matches the lunar/East Asian age computed here.