Definition
Customer growth rate is how fast the customer base grows, after customers who left are taken into account.
Formula
Customer growth rate = (customers at the end − customers at the start) ÷ customers at the start × 100.
Example
From 500 to 560 customers in a quarter is 12% growth.
Reading it
Growth combines acquisition and churn: 12% growth could be 20% new customers minus 8% churn. Look at both parts separately; high churn hidden by strong acquisition gets expensive.