function calculateGRR() {
var startingMRR = parseFloat(document.getElementById("startingMRR").value);
var churnRevenue = parseFloat(document.getElementById("churnRevenue").value) || 0;
var downgradeRevenue = parseFloat(document.getElementById("downgradeRevenue").value) || 0;
var resultBox = document.getElementById("grrResultBox");
var resultDisplay = document.getElementById("grrValue");
var summaryDisplay = document.getElementById("grrSummary");
if (!startingMRR || startingMRR <= 0) {
alert("Please enter a valid Starting MRR greater than 0.");
return;
}
// Logic: GRR = (Starting MRR – Churn – Downgrade) / Starting MRR
var retainedRevenue = startingMRR – churnRevenue – downgradeRevenue;
// Ensure we don't show negative retention if losses exceed starting MRR
if (retainedRevenue = 90) {
status = "This is a healthy retention rate for most SaaS businesses.";
} else if (grrPercentage >= 75) {
status = "Your retention is average, but there is room to reduce churn or downgrades.";
} else {
status = "This retention rate is low. Investigate why customers are leaving or downgrading.";
}
summaryDisplay.innerHTML = "You retained $" + retainedRevenue.toLocaleString() + " of your original revenue. " + status;
resultBox.style.display = "block";
}
How to Calculate Gross Retention Rate (GRR)
Gross Retention Rate (GRR) is one of the most critical metrics for SaaS and subscription-based businesses. It measures a company's ability to retain its existing customer revenue over a specific period, excluding any expansion revenue like upsells or cross-sells.
The Gross Retention Rate Formula
To calculate the Gross Retention Rate, you need to look at the revenue you started with and subtract the revenue lost from customers leaving (churn) or moving to cheaper plans (downgrades).
Starting MRR: The total Monthly Recurring Revenue at the beginning of the period.
Churn: Revenue lost from customers who canceled their subscriptions entirely.
Downgrades: Revenue lost when existing customers switch to a lower-priced tier or reduce their usage.
Note: Gross Retention cannot exceed 100%. If you want to include expansion revenue (upsells), you should calculate Net Retention Rate (NRR) instead.
Why GRR Matters More Than You Think
While Net Retention shows how much your company is growing through its current base, Gross Retention shows how stable that base actually is. A high NRR can sometimes mask a "leaky bucket" if expansion revenue is high but many customers are still leaving. GRR exposes that leak. Most successful enterprise SaaS companies aim for a Gross Retention Rate of 90% or higher.
Example Calculation
Imagine your SaaS company starts the month with $100,000 in MRR. During that month:
Three customers cancel, resulting in $5,000 of churn.
Two customers downgrade their plans, resulting in $2,000 of lost revenue.
One customer upgrades their plan, adding $3,000 of expansion revenue (This is ignored in GRR).