How to Calculate Your Lunar Age (Chinese Virtual Age) — Step by Step

The Chinese gender chart doesn’t run on your birth certificate — it runs on the traditional Chinese counting system called virtual age (虚岁, xūsuì). Here’s the whole math in four steps.

Rule 1: you are born age 1

In China’s traditional counting, the time in the womb counts as life. You arrive age 1, not 0.

Rule 2: everyone gains a year at Chinese New Year

Aging happens not on your birthday but at Spring Festival (Chinese New Year). So:

Lunar age = (lunar year at the moment — lunar year of birth) + 1

Worked example

• Mother born January 15, 1989. The 1989 lunar year started February 6, 1989 — she was born before it, so her lunar birth year is 1988.
• Conception on June 5, 2018 → lunar year 2018.
• Lunar age = (2018 − 1988) + 1 = 31.
• June 5, 2018 was lunar month 4 (April 22, 2018 in lunar terms… at day 22) → lunar month 4.
• Chart cell: age 31 × month 4 → girl, says the chart.

Where people slip up

1. Forgetting the New Year boundary. Anyone born in January or February needs to check whether CNY had already happened that year.
2. Using the conception month in Gregorian. Lunar months start on new-moon days, which wander across our months.
3. Ignoring leap lunar months. Some years (like 2025) have 13 lunar months.

Skip the math entirely

Our lunar age calculator uses the full lunisolar tables (1900–2100) so Chinese New Year boundaries and leap months are handled precisely — and the main gender predictor computes the whole thing from plain dates.