The Total Fertility Rate (TFR) is a synthetic measure representing the average number of children a woman would have if she experienced current age-specific fertility rates throughout her reproductive life. It's a key demographic indicator used to understand population growth and replacement levels.
function calculateTFR() {
var age0to4 = parseFloat(document.getElementById("age0to4").value);
var age5to9 = parseFloat(document.getElementById("age5to9").value);
var age10to14 = parseFloat(document.getElementById("age10to14").value);
var age15to19 = parseFloat(document.getElementById("age15to19").value);
var age20to24 = parseFloat(document.getElementById("age20to24").value);
var age25to29 = parseFloat(document.getElementById("age25to29").value);
var age30to34 = parseFloat(document.getElementById("age30to34").value);
var age35to39 = parseFloat(document.getElementById("age35to39").value);
var age40to44 = parseFloat(document.getElementById("age40to44").value);
var age45to49 = parseFloat(document.getElementById("age45to49").value);
var agePeriod = parseFloat(document.getElementById("agePeriod").value);
var resultElement = document.getElementById("result");
resultElement.innerHTML = ""; // Clear previous result
// Basic validation
if (isNaN(age0to4) || isNaN(age5to9) || isNaN(age10to14) || isNaN(age15to19) || isNaN(age20to24) ||
isNaN(age25to29) || isNaN(age30to34) || isNaN(age35to39) || isNaN(age40to44) || isNaN(age45to49) || isNaN(agePeriod) || agePeriod <= 0) {
resultElement.innerHTML = "Please enter valid numbers for all fertility rates and a positive age period.";
return;
}
// TFR calculation
// The formula for TFR is the sum of age-specific fertility rates multiplied by the age interval.
// ASFR = (Number of births to women aged x to x+n) / (Total number of women aged x to x+n)
// TFR = Sum(ASFR * n) for all reproductive age groups
var totalFertilityRate = (age0to4 + age5to9 + age10to14 + age15to19 + age20to24 +
age25to29 + age30to34 + age35to39 + age40to44 + age45to49) * agePeriod;
resultElement.innerHTML = "The calculated Total Fertility Rate (TFR) is: " + totalFertilityRate.toFixed(2) + " children per woman.";
}
.calculator-container {
font-family: sans-serif;
border: 1px solid #ccc;
padding: 20px;
border-radius: 8px;
max-width: 600px;
margin: 20px auto;
background-color: #f9f9f9;
}
.calculator-container h2 {
text-align: center;
margin-bottom: 15px;
color: #333;
}
.calculator-container p {
margin-bottom: 20px;
line-height: 1.6;
color: #555;
}
.input-section {
display: grid;
grid-template-columns: repeat(2, 1fr);
gap: 15px;
margin-bottom: 20px;
}
.input-section label {
display: block;
margin-bottom: 5px;
font-weight: bold;
color: #444;
}
.input-section input[type="number"] {
width: 100%;
padding: 10px;
border: 1px solid #ddd;
border-radius: 4px;
box-sizing: border-box; /* Important for consistent sizing */
}
.calculator-container button {
display: block;
width: 100%;
padding: 12px 20px;
background-color: #007bff;
color: white;
border: none;
border-radius: 4px;
cursor: pointer;
font-size: 16px;
transition: background-color 0.3s ease;
}
.calculator-container button:hover {
background-color: #0056b3;
}
#result {
margin-top: 20px;
padding: 15px;
background-color: #e7f3fe;
border-left: 6px solid #007bff;
border-radius: 4px;
text-align: center;
font-size: 1.1em;
color: #333;
}