Please enter valid positive numbers. Beginning Value cannot be zero.
Average Monthly Growth Rate (CMGR): 0.00%
Total Growth Over Period: 0.00%
Absolute Difference: 0
function calculateAMGR() {
var startVal = parseFloat(document.getElementById('startValue').value);
var endVal = parseFloat(document.getElementById('endValue').value);
var months = parseFloat(document.getElementById('periodMonths').value);
var errorDiv = document.getElementById('amgrError');
var resultDiv = document.getElementById('amgrResult');
// Reset display
errorDiv.style.display = 'none';
resultDiv.style.display = 'none';
// Validation
if (isNaN(startVal) || isNaN(endVal) || isNaN(months) || months = 0.
var cmgrDecimal = Math.pow(growthRatio, 1 / months) – 1;
var cmgrPercent = cmgrDecimal * 100;
var totalGrowthDecimal = (endVal – startVal) / startVal;
var totalGrowthPercent = totalGrowthDecimal * 100;
var diff = endVal – startVal;
// Display Results
document.getElementById('resRate').innerText = cmgrPercent.toFixed(2) + "%";
document.getElementById('resTotal').innerText = totalGrowthPercent.toFixed(2) + "%";
document.getElementById('resDiff').innerText = diff.toLocaleString();
resultDiv.style.display = 'block';
}
How to Calculate Average Monthly Growth Rate
Understanding your growth trajectory is fundamental for business analysis, social media tracking, and financial forecasting. Whether you are tracking Monthly Recurring Revenue (MRR), active users, or website traffic, the Average Monthly Growth Rate (AMGR) gives you a smoothed-out percentage representing how much your metric compounds each month.
The Formula
While a simple average calculates the mean of individual monthly percentages, the most accurate way to measure growth over time between two distinct points is the Compound Monthly Growth Rate (CMGR) formula. This is the logic used in the calculator above.
Ending Value: The metric at the end of the time period.
Beginning Value: The metric at the start of the time period.
Months: The duration of the period in months.
Example Calculation
Let's say you run a subscription business. You started the year (Month 0) with 500 subscribers. By the end of the year (12 months later), you had 1,200 subscribers.
To find the average monthly compounded growth:
Divide End by Start: 1,200 / 500 = 2.4
Calculate the exponent (1 divided by months): 1 / 12 = 0.0833
Apply the exponent: 2.40.0833 ≈ 1.0759
Subtract 1: 1.0759 - 1 = 0.0759
Convert to percentage: 0.0759 * 100 = 7.59%
Your subscriber base grew at an average rate of 7.59% per month.
Why Use CMGR instead of Simple Average?
A simple average can be misleading if your growth fluctuates wildly. CMGR is superior because it connects the starting point directly to the ending point, accounting for the compounding effect. If you grew by 7.59% every single month starting at 500, you would land exactly at 1,200 after 12 months. This makes it an essential metric for projecting future performance.
Key Metrics to Track
You can use the calculator above to track various Key Performance Indicators (KPIs):
Revenue Growth: Track MRR or ARR expansion.
User Acquisition: Measure the growth of registered users or newsletter subscribers.
Portfolio Value: Calculate the monthly return on an investment portfolio.
Traffic: Monitor website session increases over a quarter or year.