body {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
line-height: 1.6;
color: #333;
margin: 0;
padding: 0;
}
.calculator-wrapper {
max-width: 800px;
margin: 40px auto;
padding: 20px;
background: #f9f9f9;
border-radius: 8px;
box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}
.calc-header {
text-align: center;
margin-bottom: 30px;
color: #2c3e50;
}
.input-group {
margin-bottom: 20px;
}
.input-group label {
display: block;
margin-bottom: 8px;
font-weight: 600;
color: #555;
}
.input-group input {
width: 100%;
padding: 12px;
border: 1px solid #ddd;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box; /* Important for padding */
}
.input-group input:focus {
border-color: #3498db;
outline: none;
}
.calc-btn {
width: 100%;
padding: 15px;
background-color: #3498db;
color: white;
border: none;
border-radius: 4px;
font-size: 18px;
font-weight: bold;
cursor: pointer;
transition: background-color 0.3s;
}
.calc-btn:hover {
background-color: #2980b9;
}
.results-container {
margin-top: 30px;
padding: 20px;
background-color: #fff;
border-left: 5px solid #3498db;
border-radius: 4px;
display: none; /* Hidden by default */
}
.result-row {
display: flex;
justify-content: space-between;
margin-bottom: 15px;
border-bottom: 1px solid #eee;
padding-bottom: 10px;
}
.result-row:last-child {
border-bottom: none;
margin-bottom: 0;
}
.result-label {
font-weight: 600;
color: #555;
}
.result-value {
font-weight: 700;
color: #2c3e50;
font-size: 1.1em;
}
.article-section {
max-width: 800px;
margin: 50px auto;
padding: 0 20px;
}
.article-section h2 {
color: #2c3e50;
margin-top: 30px;
}
.article-section p {
margin-bottom: 15px;
}
.article-section ul {
margin-bottom: 15px;
}
.error-msg {
color: #e74c3c;
text-align: center;
margin-top: 10px;
display: none;
font-weight: bold;
}
function calculateNetMigration() {
// 1. Get DOM elements
var immigrantsInput = document.getElementById('numImmigrants');
var emigrantsInput = document.getElementById('numEmigrants');
var populationInput = document.getElementById('totalPopulation');
var errorDiv = document.getElementById('errorDisplay');
var resultsDiv = document.getElementById('resultsArea');
var resRate = document.getElementById('resRate');
var resAbsolute = document.getElementById('resAbsolute');
var resTrend = document.getElementById('resTrend');
// 2. Parse values
var immigrants = parseFloat(immigrantsInput.value);
var emigrants = parseFloat(emigrantsInput.value);
var population = parseFloat(populationInput.value);
// 3. Validation logic
errorDiv.style.display = 'none';
resultsDiv.style.display = 'none';
if (isNaN(immigrants) || isNaN(emigrants) || isNaN(population)) {
errorDiv.innerHTML = "Please enter valid numbers for all fields.";
errorDiv.style.display = 'block';
return;
}
if (population <= 0) {
errorDiv.innerHTML = "Total population must be greater than zero.";
errorDiv.style.display = 'block';
return;
}
if (immigrants < 0 || emigrants 0) {
trendText = "Positive (Inflow)";
trendColor = "#27ae60"; // Green
} else if (netMigrationAbsolute < 0) {
trendText = "Negative (Outflow)";
trendColor = "#c0392b"; // Red
} else {
trendText = "Balanced (Zero Net)";
trendColor = "#7f8c8d"; // Grey
}
// 7. Format and Display Results
resAbsolute.innerHTML = netMigrationAbsolute.toLocaleString();
resRate.innerHTML = netMigrationRate.toFixed(2);
resTrend.innerHTML = trendText;
resTrend.style.color = trendColor;
resultsDiv.style.display = 'block';
}
Understanding Net Migration Rate
The Net Migration Rate is a critical demographic indicator used to determine the contribution of migration to a specific region's population change. Unlike natural population change (births minus deaths), net migration focuses strictly on the movement of people across borders.
How to Calculate Net Migration Rate
The calculation involves three primary variables: the number of people entering a region (Immigrants), the number of people leaving that region (Emigrants), and the total mid-year population. The standard formula expresses this rate per 1,000 people to make it comparable across countries of different sizes.
The Formula:
NMR = ((Immigrants – Emigrants) / Total Population) × 1,000
- Immigrants (I): People moving into the country or region.
- Emigrants (E): People moving out of the country or region.
- Total Population (P): The estimated population of the area.
Interpreting the Results
Once you calculate the rate, the result tells you the direction of migration flow relative to the population size:
- Positive Rate: Indicates that more people are entering than leaving. This contributes to population growth and can increase the labor supply.
- Negative Rate: Indicates that more people are leaving than entering. This is often referred to as "brain drain" if skilled workers are leaving, and it contributes to population decline.
- Zero: Indicates that immigration and emigration are balanced.
Example Calculation
Let's assume a fictional country has a population of 5,000,000 people. In a given year, 25,000 people immigrate to the country, while 10,000 people emigrate.
- Net Migration (Absolute): 25,000 – 10,000 = 15,000 people.
- Raw Ratio: 15,000 / 5,000,000 = 0.003
- Rate per 1,000: 0.003 × 1,000 = 3.00
This means for every 1,000 people already living in the country, the population grew by 3 people due to migration.
Why is this Metric Important?
Demographers and economists use the Net Migration Rate to forecast future population sizes, plan for infrastructure needs (like housing and schools), and understand labor market dynamics. High positive net migration typically correlates with economic opportunity, while high negative rates may signal economic distress or political instability.