How Do You Calculate Average Growth Rate in Excel?
Calculating the average growth rate is a fundamental skill for financial analysts, business owners, and investors. While you can calculate a simple average (AAGR), the most accurate method for measuring growth over time is the Compound Annual Growth Rate (CAGR). This accounts for the effect of compounding, which simple averages ignore.
Method 1: The Basic Mathematical Formula
In Excel, you can calculate the growth rate using the standard mathematical formula. If your Beginning Value is in cell A1, Ending Value in B1, and the Number of Periods in C1, use this formula:
=((B1/A1)^(1/C1))-1
Method 2: Using the RRI Function
Excel provides a built-in function specifically for calculating the average interest rate or growth rate for a given period. This is often the cleanest way to find CAGR:
=RRI(number_of_periods, start_value, end_value)
Step-by-Step Example
Suppose your company's revenue was $50,000 in 2018 and grew to $120,000 by 2023 (a period of 5 years).
Beginning Value: 50,000
Ending Value: 120,000
Periods: 5
Using our calculator or Excel, the CAGR is 19.13% per year. This means the revenue grew by an average of 19.13% every year for five years to reach the final amount.
Why Use CAGR instead of Average Growth?
Simple average growth (adding up yearly percentages and dividing by the count) can be misleading. For example, if a stock drops 50% one year and gains 50% the next, the simple average is 0%, but you have actually lost 25% of your money. CAGR provides the "smoothed" rate that describes the true geometric progression of the investment.
function calculateGrowth() {
var startVal = parseFloat(document.getElementById('startVal').value);
var endVal = parseFloat(document.getElementById('endVal').value);
var periods = parseFloat(document.getElementById('periodCount').value);
var resultsDiv = document.getElementById('results');
if (isNaN(startVal) || isNaN(endVal) || isNaN(periods) || periods <= 0 || startVal === 0) {
alert("Please enter valid positive numbers. Beginning value cannot be zero.");
return;
}
// CAGR Formula: ((End / Start)^(1 / Periods)) – 1
var cagr = (Math.pow((endVal / startVal), (1 / periods)) – 1);
var totalGrowth = ((endVal – startVal) / startVal);
var absoluteDiff = endVal – startVal;
document.getElementById('cagrResult').innerText = (cagr * 100).toFixed(2) + "%";
document.getElementById('totalGrowthResult').innerText = (totalGrowth * 100).toFixed(2) + "%";
document.getElementById('absoluteResult').innerText = absoluteDiff.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
// Update the Excel helper text dynamically
document.getElementById('excelFormula').innerHTML = "Excel Formula: =((" + endVal + "/" + startVal + ")^(1/" + periods + "))-1";
resultsDiv.style.display = 'block';
}