How the Chinese Gender Calendar Works

Step 1: Mother's Lunar Age

The chart does not use Western age directly. It uses traditional Chinese lunar age at conception. That value comes from the lunar birth year and the lunar year of the conception date, using nominal age counting.

Step 2: Lunar Conception Month

The conception date is converted from the Gregorian calendar into the lunar calendar. The month used in the chart is the lunar conception month, which may not match the Gregorian month name.

Step 3: Chart Lookup

Once lunar age and lunar month are known, the traditional chart is a simple lookup: age selects the row and month selects the column. The current version uses one consistent V1 chart so the same input dates always produce the same result.

Leap Month Handling

Some lunar years contain a leap month. The V1 predictor keeps leap months in the same chart month number for a stable and explainable rule. When a result comes from a leap month, the details panel shows that status to the user.

Why the Details Matter

A Gregorian date close to Chinese New Year or a lunar-month boundary can change the lunar year, lunar age or lunar month. That is why the predictor converts exact dates instead of asking users to choose a month manually.

Folklore Caveat

The calculation is deterministic, but the tradition itself is not a medical or scientific method for determining fetal sex. Treat the result as cultural entertainment and use clinical care for medical questions.