function calculateGrowth() {
// Get input values
var startVal = parseFloat(document.getElementById('initialValue').value);
var endVal = parseFloat(document.getElementById('finalValue').value);
var periods = parseFloat(document.getElementById('numPeriods').value);
var errorDiv = document.getElementById('errorMessage');
var resultsDiv = document.getElementById('results');
// Reset display
errorDiv.style.display = 'none';
resultsDiv.style.display = 'none';
errorDiv.innerText = "";
// Validation
if (isNaN(startVal) || isNaN(endVal) || isNaN(periods)) {
errorDiv.innerText = "Please enter valid numbers in all fields.";
errorDiv.style.display = 'block';
return;
}
if (periods <= 0) {
errorDiv.innerText = "Number of years must be greater than zero.";
errorDiv.style.display = 'block';
return;
}
if (startVal === 0) {
errorDiv.innerText = "Beginning Value cannot be zero (cannot divide by zero).";
errorDiv.style.display = 'block';
return;
}
// Calculations
// 1. Absolute Change
var absChange = endVal – startVal;
// 2. Total Percentage Growth
var totalPercent = (absChange / startVal) * 100;
// 3. CAGR Formula: (End / Start)^(1 / n) – 1
// Note: If values are negative, Math.pow might result in NaN for fractional exponents.
var cagr = 0;
// Handling negative bases with fractional exponents requires specific logic or is undefined in real numbers context for business growth
// For standard growth calculator, we assume positive entity values (Revenue, Population, etc.)
if (startVal < 0 || endVal < 0) {
// Allow calculation but warn if sign flips make CAGR undefined mathematically (complex numbers)
// Simple approach: if signs match, we can calculate. If signs differ, CAGR is undefined.
if ((startVal 0) || (startVal > 0 && endVal < 0)) {
errorDiv.innerText = "CAGR cannot be calculated when value signs flip (positive to negative or vice versa).";
errorDiv.style.display = 'block';
return;
}
// If both negative, we treat the magnitude logic carefully or standard formula applies
cagr = (Math.pow((endVal / startVal), (1 / periods)) – 1) * 100;
} else {
cagr = (Math.pow((endVal / startVal), (1 / periods)) – 1) * 100;
}
var multiplier = endVal / startVal;
// Output formatting
document.getElementById('cagrResult').innerText = cagr.toFixed(2) + "%";
document.getElementById('totalPercentResult').innerText = totalPercent.toFixed(2) + "%";
document.getElementById('absChangeResult').innerText = absChange.toFixed(2);
document.getElementById('multiplierResult').innerText = multiplier.toFixed(2) + "x";
// Show results
resultsDiv.style.display = 'block';
}
How to Calculate Annual Percentage Growth Rate
Understanding the rate at which an asset, revenue stream, or population grows over time is fundamental to financial analysis and business planning. The Annual Percentage Growth Rate, most commonly referred to in finance as the Compound Annual Growth Rate (CAGR), provides a smoothed annual average of growth over a specific period.
Unlike a simple average growth rate, which can be misleading due to volatility, this calculation assumes the investment grew at a steady rate every single year to arrive at the final ending value.
The Formula
To calculate the annual percentage growth rate, you need three numbers: the beginning value, the ending value, and the number of years (or periods) that have passed.
APGR = ( Ending Value / Beginning Value )( 1 / n ) – 1
Where:
Ending Value: The value at the end of the period.
Beginning Value: The value at the start of the period.
n: The number of years or periods.
Example Calculation
Let's say you invested in a startup. Your initial investment (Beginning Value) was $10,000. After 5 years, your stake is worth $25,000 (Ending Value). How much did your money grow per year?
Divide the Ending Value by the Beginning Value: 25,000 / 10,000 = 2.5
Raise the result to the power of one divided by the number of years (1/5 = 0.2): 2.50.2 ≈ 1.2011
Subtract 1 from the result: 1.2011 - 1 = 0.2011
Multiply by 100 to get the percentage: 0.2011 * 100 = 20.11%
This means your investment grew at an annual rate of roughly 20.11%.
Why Use Annual Percentage Growth Rate?
This metric is superior to absolute growth rates for comparing different investments because it standardizes the time factor. A 50% total return over 2 years is very different from a 50% total return over 10 years. The APGR/CAGR formula normalizes these returns so you can compare them apples-to-apples.
Common Use Cases
Revenue Growth: Analyzing how fast a company's sales are increasing over a 3-5 year horizon.
Investment Returns: determining the performance of a portfolio or specific stock.
User Base: Calculating the growth of subscribers or app users for SaaS companies.
Population Statistics: Measuring demographic shifts in cities or countries.