Enter the number of live births and the total female population for each 5-year age group.
Age Group
Live Births
Female Population
15-19
20-24
25-29
30-34
35-39
40-44
45-49
Total Fertility Rate (TFR):–
Classification:–
Sum of ASFR (per woman):–
*Calculated based on 5-year age intervals.
How to Calculate Total Fertility Rate
The Total Fertility Rate (TFR) is a standard demographic indicator used to estimate the average number of children a woman would have over her childbearing years (usually ages 15-49), assuming current age-specific fertility rates remain constant throughout her reproductive life.
The TFR Formula
The calculation involves summing the Age-Specific Fertility Rates (ASFR) for each age group and multiplying by the size of the age interval. Since demographic data is typically collected in 5-year intervals, the formula is:
TFR = 5 × ∑ (ASFR)
Where:
ASFR = (Live Births in Age Group) ÷ (Female Population in Age Group)
5 = The age interval (e.g., 15-19 covers 5 years).
Example Calculation
Consider a hypothetical population with the following data:
Age Group
Births
Population
ASFR (Births/Pop)
15-19
1,000
50,000
0.020
20-24
4,500
45,000
0.100
25-29
5,000
40,000
0.125
30-34
3,500
35,000
0.100
35-39
1,500
30,000
0.050
40-44
300
25,000
0.012
45-49
50
20,000
0.0025
Sum
0.4095
Calculation:
Sum of ASFR = 0.4095
TFR = 0.4095 × 5 = 2.05 children per woman.
Understanding the Result
Replacement Level (2.1): The rate needed for a population to replace itself from one generation to the next, without migration.
Below 2.1: Indicates a population that may shrink over time (sub-replacement fertility).
Above 2.1: Indicates a growing population.
function calculateTFR() {
var groups = ['15_19′, '20_24′, '25_29′, '30_34′, '35_39′, '40_44′, '45_49′];
var sumASFR = 0;
var hasData = false;
for (var i = 0; i 0) {
var asfr = births / women;
sumASFR += asfr;
hasData = true;
}
}
if (!hasData) {
alert("Please enter valid numbers for Births and Population (Population must be greater than 0) for at least one age group.");
return;
}
// TFR Formula: Sum of ASFR * 5 (since age groups are 5-year intervals)
var tfr = sumASFR * 5;
// Display results
document.getElementById('finalTFR').innerText = tfr.toFixed(2);
document.getElementById('sumASFR').innerText = sumASFR.toFixed(4);
// Determine Classification
var classification = "";
var classificationColor = "";
if (tfr < 1.3) {
classification = "Lowest-Low Fertility";
classificationColor = "#c0392b";
} else if (tfr = 2.1 && tfr < 2.2) {
classification = "Replacement Level";
classificationColor = "#27ae60";
} else {
classification = "Above Replacement Level";
classificationColor = "#2980b9";
}
var classEl = document.getElementById('fertilityClass');
classEl.innerText = classification;
classEl.style.color = classificationColor;
document.getElementById('tfrResult').style.display = 'block';
}
function resetTFR() {
var inputs = document.getElementsByTagName('input');
for (var i = 0; i < inputs.length; i++) {
inputs[i].value = '';
}
document.getElementById('tfrResult').style.display = 'none';
}