How Chinese lunar age is counted
This calculator follows a traditional nominal-age convention: you are one year old at birth and gain one year at each Chinese New Year. That makes your lunar age different from your completed years since birth.
Lunar age = target lunar year − birth lunar year + 1
The important detail is lunar year. A birthday in January or early February may belong to the preceding lunar year. Simply adding one to your regular age can give the wrong answer.
A worked example
Someone born on June 1, 2000 belongs to lunar year 2000. On February 16, 2026, the lunar year is still 2025, so their lunar age is 2025 − 2000 + 1 = 26. The next day is Chinese New Year: the lunar year changes to 2026 and their lunar age becomes 27.
Using this age with the gender chart
The traditional gender chart uses age at conception. Choose that date here if you are looking up the chart manually. The Chinese gender predictor performs this conversion automatically and also finds the lunar conception month.
The age calculation describes a calendar convention. It does not add scientific validity to the gender chart. Read the evidence on prediction accuracy.
Dates and limits
The date converter accepts years 1900 to 2099. The gender chart itself only contains lunar ages 18 to 45; this separate age calculator can display ages outside that range. Very distant future calendar dates can be subject to astronomical calculation differences near midnight.
Calendar conversion: lunar-javascript. Independent date reference: Hong Kong Observatory conversion tables.