function calculateChineseDueAndGender() {
var motherBirthDateStr = document.getElementById("motherBirthDate").value;
var conceptionDateStr = document.getElementById("conceptionDate").value;
var errorDiv = document.getElementById("errorMessages");
errorDiv.innerHTML = ""; // Clear previous errors
if (!motherBirthDateStr || !conceptionDateStr) {
errorDiv.innerHTML = "Please enter both Mother's Birth Date and Estimated Conception Date.";
document.getElementById("lunarAgeResult").innerHTML = "Mother's Lunar Age at Conception: –";
document.getElementById("lunarMonthResult").innerHTML = "Lunar Month of Conception: –";
document.getElementById("predictedGenderResult").innerHTML = "Predicted Gender: –";
document.getElementById("estimatedDueDateResult").innerHTML = "Estimated Due Date: –";
return;
}
var motherBirthDate = new Date(motherBirthDateStr);
var conceptionDate = new Date(conceptionDateStr);
if (isNaN(motherBirthDate.getTime()) || isNaN(conceptionDate.getTime())) {
errorDiv.innerHTML = "Invalid date format. Please use YYYY-MM-DD.";
document.getElementById("lunarAgeResult").innerHTML = "Mother's Lunar Age at Conception: –";
document.getElementById("lunarMonthResult").innerHTML = "Lunar Month of Conception: –";
document.getElementById("predictedGenderResult").innerHTML = "Predicted Gender: –";
document.getElementById("estimatedDueDateResult").innerHTML = "Estimated Due Date: –";
return;
}
if (conceptionDate < motherBirthDate) {
errorDiv.innerHTML = "Conception Date cannot be before Mother's Birth Date.";
document.getElementById("lunarAgeResult").innerHTML = "Mother's Lunar Age at Conception: –";
document.getElementById("lunarMonthResult").innerHTML = "Lunar Month of Conception: –";
document.getElementById("predictedGenderResult").innerHTML = "Predicted Gender: –";
document.getElementById("estimatedDueDateResult").innerHTML = "Estimated Due Date: –";
return;
}
// — Calculate Mother's Lunar Age at Conception (simplified for chart) —
// Common simplification: Lunar age is (Western Conception Year – Western Birth Year) + 1
var motherBirthYear = motherBirthDate.getFullYear();
var conceptionYear = conceptionDate.getFullYear();
var lunarAge = (conceptionYear – motherBirthYear) + 1;
// — Calculate Lunar Month of Conception (simplified for chart) —
// Common simplification: Use the Western month number as the Lunar Month
var lunarMonth = conceptionDate.getMonth() + 1; // getMonth() is 0-indexed
// — Validate Lunar Age for Chart Range (typically 18-45) —
if (lunarAge 45) {
errorDiv.innerHTML = "The Chinese Gender Chart is typically used for mother's lunar ages between 18 and 45. Your calculated lunar age is " + lunarAge + ".";
document.getElementById("lunarAgeResult").innerHTML = "Mother's Lunar Age at Conception: " + lunarAge;
document.getElementById("lunarMonthResult").innerHTML = "Lunar Month of Conception: " + lunarMonth;
document.getElementById("predictedGenderResult").innerHTML = "Predicted Gender: (Age out of chart range)";
document.getElementById("estimatedDueDateResult").innerHTML = "Estimated Due Date: –";
return;
}
// — Chinese Gender Chart Data —
// This chart is a common representation. Rows are Lunar Age (18-45), Columns are Lunar Month (1-12).
// 'B' for Boy, 'G' for Girl.
// Note: Many online charts are variations of this pattern.
var chineseGenderChart = [
// Month: 1 2 3 4 5 6 7 8 9 10 11 12
['B', 'G', 'B', 'G', 'G', 'B', 'B', 'B', 'B', 'B', 'B', 'G'], // Age 18 (Index 0)
['G', 'B', 'G', 'B', 'B', 'G', 'G', 'G', 'G', 'G', 'G', 'B'], // Age 19 (Index 1)
['B', 'G', 'B', 'G', 'G', 'B', 'B', 'B', 'B', 'B', 'B', 'G'], // Age 20 (Index 2)
['G', 'B', 'G', 'B', 'B', 'G', 'G', 'G', 'G', 'G', 'G', 'B'], // Age 21 (Index 3)
['B', 'G', 'B', 'G', 'G', 'B', 'B', 'B', 'B', 'B', 'B', 'G'], // Age 22 (Index 4)
['G', 'B', 'G', 'B', 'B', 'G', 'G', 'G', 'G', 'G', 'G', 'B'], // Age 23 (Index 5)
['B', 'G', 'B', 'G', 'G', 'B', 'B', 'B', 'B', 'B', 'B', 'G'], // Age 24 (Index 6)
['G', 'B', 'G', 'B', 'B', 'G', 'G', 'G', 'G', 'G', 'G', 'B'], // Age 25 (Index 7)
['B', 'G', 'B', 'G', 'G', 'B', 'B', 'B', 'B', 'B', 'B', 'G'], // Age 26 (Index 8)
['G', 'B', 'G', 'B', 'B', 'G', 'G', 'G', 'G', 'G', 'G', 'B'], // Age 27 (Index 9)
['B', 'G', 'B', 'G', 'G', 'B', 'B', 'B', 'B', 'B', 'B', 'G'], // Age 28 (Index 10)
['G', 'B', 'G', 'B', 'B', 'G', 'G', 'G', 'G', 'G', 'G', 'B'], // Age 29 (Index 11)
['B', 'G', 'B', 'G', 'G', 'B', 'B', 'B', 'B', 'B', 'B', 'G'], // Age 30 (Index 12)
['G', 'B', 'G', 'B', 'B', 'G', 'G', 'G', 'G', 'G', 'G', 'B'], // Age 31 (Index 13)
['B', 'G', 'B', 'G', 'G', 'B', 'B', 'B', 'B', 'B', 'B', 'G'], // Age 32 (Index 14)
['G', 'B', 'G', 'B', 'B', 'G', 'G', 'G', 'G', 'G', 'G', 'B'], // Age 33 (Index 15)
['B', 'G', 'B', 'G', 'G', 'B', 'B', 'B', 'B', 'B', 'B', 'G'], // Age 34 (Index 16)
['G', 'B', 'G', 'B', 'B', 'G', 'G', 'G', 'G', 'G', 'G', 'B'], // Age 35 (Index 17)
['B', 'G', 'B', 'G', 'G', 'B', 'B', 'B', 'B', 'B', 'B', 'G'], // Age 36 (Index 18)
['G', 'B', 'G', 'B', 'B', 'G', 'G', 'G', 'G', 'G', 'G', 'B'], // Age 37 (Index 19)
['B', 'G', 'B', 'G', 'G', 'B', 'B', 'B', 'B', 'B', 'B', 'G'], // Age 38 (Index 20)
['G', 'B', 'G', 'B', 'B', 'G', 'G', 'G', 'G', 'G', 'G', 'B'], // Age 39 (Index 21)
['B', 'G', 'B', 'G', 'G', 'B', 'B', 'B', 'B', 'B', 'B', 'G'], // Age 40 (Index 22)
['G', 'B', 'G', 'B', 'B', 'G', 'G', 'G', 'G', 'G', 'G', 'B'], // Age 41 (Index 23)
['B', 'G', 'B', 'G', 'G', 'B', 'B', 'B', 'B', 'B', 'B', 'G'], // Age 42 (Index 24)
['G', 'B', 'G', 'B', 'B', 'G', 'G', 'G', 'G', 'G', 'G', 'B'], // Age 43 (Index 25)
['B', 'G', 'B', 'G', 'G', 'B', 'B', 'B', 'B', 'B', 'B', 'G'], // Age 44 (Index 26)
['G', 'B', 'G', 'B', 'B', 'G', 'G', 'G', 'G', 'G', 'G', 'B'] // Age 45 (Index 27)
];
var predictedGender = "N/A";
var ageIndex = lunarAge – 18; // Adjust for 0-indexed array
var monthIndex = lunarMonth – 1; // Adjust for 0-indexed array
if (ageIndex >= 0 && ageIndex = 0 && monthIndex < 12) {
predictedGender = chineseGenderChart[ageIndex][monthIndex];
predictedGender = (predictedGender === 'B') ? 'Boy' : 'Girl';
} else {
predictedGender = "Cannot predict (Age or Month out of chart range)";
}
// — Calculate Estimated Due Date (standard 266 days from conception) —
var dueDate = new Date(conceptionDate.getTime());
dueDate.setDate(conceptionDate.getDate() + 266); // Average gestation period from conception
var options = { year: 'numeric', month: 'long', day: 'numeric' };
var formattedDueDate = dueDate.toLocaleDateString('en-US', options);
// — Display Results —
document.getElementById("lunarAgeResult").innerHTML = "Mother's Lunar Age at Conception: " + lunarAge + " years";
document.getElementById("lunarMonthResult").innerHTML = "Lunar Month of Conception: " + lunarMonth;
document.getElementById("predictedGenderResult").innerHTML = "Predicted Gender: " + predictedGender;
document.getElementById("estimatedDueDateResult").innerHTML = "Estimated Due Date: " + formattedDueDate;
}
Understanding the Chinese Due Date & Gender Predictor
The Chinese Due Date & Gender Predictor is a popular, ancient chart believed to forecast a baby's gender based on two key factors: the mother's lunar age at the time of conception and the lunar month in which conception occurred. While often referred to as a "due date calculator," its primary traditional use is for gender prediction, with the due date being a standard calculation based on the conception date.
The Legend Behind the Chart
Legend has it that the original Chinese Gender Chart was discovered in a royal tomb near Beijing over 700 years ago. It's said to have been used by the Qing Dynasty imperial family to plan for male heirs, as sons were highly valued. The chart's accuracy is often claimed to be around 90%, though scientific evidence does not support this. It's widely considered a fun, traditional folklore tool rather than a medical or scientific predictor.
How It Works: Lunar Age and Lunar Month
Unlike Western age, which counts from birth, Chinese lunar age traditionally considers a person to be one year old at birth and adds another year on each Chinese New Year. For the purpose of this chart, a common simplification is used:
Mother's Lunar Age at Conception: This calculator uses a simplified method where your lunar age is generally your Western age at conception plus one year. For example, if you were born in 1990 and conceived in 2023, your lunar age for the chart would be (2023 – 1990) + 1 = 34.
Lunar Month of Conception: While true lunar months follow the lunar calendar, for simplicity and common practice in online charts, this calculator uses the Western month number (1-12) of your conception date as the "lunar month."
These two values (lunar age and lunar month) are then cross-referenced on the ancient Chinese Gender Chart to predict whether the baby will be a boy or a girl.
Calculating Your Estimated Due Date
In addition to the gender prediction, this tool also provides an estimated due date. This calculation is based on standard medical practice:
Estimated Due Date: If you know your exact conception date, your due date is typically calculated by adding 266 days (approximately 38 weeks) to that date. This is the average length of a full-term pregnancy from conception.
Using the Calculator
To use the calculator:
Enter Mother's Birth Date: Input your birth date in the specified field.
Enter Estimated Conception Date: Input the date you believe conception occurred. If you're unsure, you can estimate based on your last menstrual period (LMP) by adding approximately 14 days to your LMP start date.
Click "Calculate": The calculator will then display your mother's lunar age and lunar month at conception, the predicted gender according to the Chinese chart, and your estimated due date.
Important Considerations
It's crucial to remember that the Chinese Due Date & Gender Predictor is a tool for entertainment and cultural interest. It should not be used for medical advice or as a definitive gender prediction. The only reliable methods for determining a baby's gender are medical tests like ultrasound, NIPT, or amniocentesis. Enjoy this calculator as a fun way to connect with ancient traditions!
Example Calculation:
Let's say the mother's birth date is January 15, 1992, and the estimated conception date is March 10, 2024.
Mother's Lunar Age at Conception: (2024 – 1992) + 1 = 33 years.
Lunar Month of Conception: March is the 3rd month, so Lunar Month = 3.
Predicted Gender: Consulting the chart for Lunar Age 33 and Lunar Month 3, the chart predicts 'Boy'.
Estimated Due Date: March 10, 2024 + 266 days = December 1, 2024.