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
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 birthTraditional reckoning starts at one and increments at the new year; the international system starts at zero and increments on the birthday.
Worked examples
- Inputs:
- birth=1990-06-15, today=2026-05-21
- Output:
- lunar 37; international 35
- Inputs:
- birth=2000-01-01, today=2026-05-21
- Output:
- lunar 27; international 26
- 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.