Calculate your churn percentage based on customer movement.
The total count of existing customers on day 1.
Customers gained during the specific time period.
The final count of customers on the last day.
Please enter valid positive numbers. Start customers cannot be zero.
Attrition Rate (Churn)
0.00%
Customers Lost
0
Retention Rate
0.00%
function calculateAttrition() {
// Get input elements by ID
var startInput = document.getElementById('customersStart');
var newInput = document.getElementById('customersNew');
var endInput = document.getElementById('customersEnd');
var errorDiv = document.getElementById('errorMsg');
var resultsDiv = document.getElementById('resultsSection');
// Parse values
var startCust = parseFloat(startInput.value);
var newCust = parseFloat(newInput.value);
var endCust = parseFloat(endInput.value);
// Validation
if (isNaN(startCust) || isNaN(newCust) || isNaN(endCust)) {
errorDiv.style.display = 'block';
errorDiv.innerText = "Please fill in all fields with valid numbers.";
resultsDiv.style.display = 'none';
return;
}
if (startCust <= 0) {
errorDiv.style.display = 'block';
errorDiv.innerText = "Start Customers must be greater than zero to calculate a rate.";
resultsDiv.style.display = 'none';
return;
}
if (startCust < 0 || newCust < 0 || endCust Start + New, which is mathematically impossible for this model
// unless there is data error. We will clamp to 0 or show error.
if (customersLost < 0) {
errorDiv.style.display = 'block';
errorDiv.innerText = "Data Error: End count cannot be higher than Start + New customers.";
resultsDiv.style.display = 'none';
return;
}
// Attrition Rate = (Customers Lost / Start Customers) * 100
var attritionRate = (customersLost / startCust) * 100;
// Retention Rate = 100 – Attrition Rate (or (End – New) / Start * 100)
var retentionRate = 100 – attritionRate;
// Display Results
errorDiv.style.display = 'none';
resultsDiv.style.display = 'block';
document.getElementById('resultRate').innerText = attritionRate.toFixed(2) + "%";
document.getElementById('resultLost').innerText = customersLost;
document.getElementById('resultRetention').innerText = retentionRate.toFixed(2) + "%";
}
What is Customer Attrition Rate?
Customer Attrition Rate, also widely known as Churn Rate, is a critical business metric that measures the percentage of customers who stop doing business with an entity during a specific time period. It is the opposite of growth; while you aim to acquire new users, attrition measures how many are leaving out the back door.
Understanding your attrition rate is vital for assessing the health of your customer base, evaluating customer satisfaction, and forecasting long-term revenue. High attrition usually signals dissatisfaction with the product, poor customer service, or better offers from competitors.
The Calculation Formula
While there are several variations depending on how you account for new customers, the standard formula for calculating attrition rate is:
Attrition Rate = (Customers Lost / Customers at Start of Period) × 100
To accurately determine the number of customers lost, you need to account for new acquisitions using this logic:
Customers Lost = (Start Customers + New Customers) – End Customers
Example Calculation
Let's assume you run a subscription service. Here is a realistic scenario for one month:
Customers at Start: 1,000
New Customers Acquired: 100
Customers at End: 1,040
First, calculate the actual number of customers lost:
Lost = (1,000 + 100) – 1,040 = 60 customers.
Next, calculate the rate:
Rate = (60 / 1,000) × 100 = 6.00%
Why Attrition Rate Matters
Tracking attrition is often more cost-effective than focusing solely on acquisition. Consider these factors:
Cost Efficiency: Acquiring a new customer can cost 5 to 25 times more than retaining an existing one.
Revenue Impact: A mere 5% increase in customer retention can increase profits by 25% to 95%.
Product Feedback: A spike in attrition often serves as an early warning system for product issues or market shifts.
Interpreting Your Results
Attrition Rate
Interpretation
0% – 3%
Excellent. High loyalty and sticky product usage.
3% – 7%
Average. Typical for many SaaS and B2B industries, but room for improvement.
8% – 15%
Concern. You are losing a significant portion of your base annually. Immediate action required.
15%+
Critical. The business model may be unsustainable without fixing the "leaky bucket."
Strategies to Reduce Attrition
If your calculation shows a high rate, consider these strategies:
Analyze Exit Data: Survey customers who leave to understand the "why."
Improve Onboarding: Ensure customers find value in your product immediately.
Proactive Support: Reach out to customers who show signs of low activity before they cancel.
Loyalty Programs: Incentivize long-term contracts or repeated usage.