How to Calculate Compound Monthly Growth Rate

Your Compound Monthly Growth Rate:

What is Compound Monthly Growth Rate (CMGR)?

The Compound Monthly Growth Rate (CMGR) is a vital metric used primarily by startups, SaaS companies, and investors to measure the average monthly growth of a specific metric (like Monthly Recurring Revenue or User Count) over a set period. Unlike simple month-over-month growth, which can fluctuate wildly, CMGR provides a smoothed-out growth rate that accounts for the compounding effect over time.

The CMGR Formula

To calculate the compound monthly growth rate, you use the following mathematical formula:

CMGR = [(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 months in the period.

Why CMGR Matters

For high-growth businesses, simple averages can be misleading. CMGR allows you to:

• Forecast Future Growth: By knowing your steady CMGR, you can project when you will hit significant milestones, such as $1M ARR.
• Benchmarking: Compare your performance against industry standards or competitors.
• Investor Reporting: Investors prefer CMGR because it demonstrates sustainable momentum rather than a one-time spike.

Practical Example

Imagine your SaaS business had 1,000 active users in January. By December (a period of 11 months from the start), you have 3,500 active users.

Using the formula: (3,500 / 1,000)^(1/11) – 1 = 1.1205 – 1 = 12.05% CMGR.

This means your user base grew at a compounded rate of roughly 12% every single month during that timeframe.

function calculateCMGR() { var startVal = parseFloat(document.getElementById('beginningValue').value); var endVal = parseFloat(document.getElementById('endingValue').value); var months = parseFloat(document.getElementById('months').value); var resultDiv = document.getElementById('cmgrResult'); var output = document.getElementById('cmgrOutput'); var description = document.getElementById('cmgrDescription'); if (isNaN(startVal) || isNaN(endVal) || isNaN(months) || startVal <= 0 || months 0) { description.innerHTML = "On average, your metric grew by " + cmgrPercentage + "% every month, compounded."; } else if (cmgrPercentage < 0) { output.style.color = "#d93025"; resultDiv.style.backgroundColor = "#fce8e6"; description.innerHTML = "Your metric saw a compound monthly decline of " + Math.abs(cmgrPercentage) + "%."; } else { description.innerHTML = "There was no growth over this period."; } }