Ecommerce KPIs
Customer retention rate.
Enter customers at the start, at the end and new customers acquired in between. See retention rate, churn, customers lost and implied lifespan.
Retention rate = (customers at end - new customers acquired) / customers at start x 100. Starting with 1,000, acquiring 300 and ending with 1,250 is 95%.
Your numbers
Result
Worked example
Start July with 1,000 customers, acquire 300 during the month and end with 1,250. Retention rate = (1,250 - 300) / 1,000 = 95%. Churn is 5%, so 50 customers were lost. If that churn stayed constant, the average customer would last 1 / 0.05 = 20 months.
How it works
Shopify defines customer retention rate as the percentage of customers you keep during a specific period: (customers at end - new customers acquired) / customers at start x 100. Its worked example (1,000 at the start, 300 acquired, 1,250 at the end) gives 95%, and this page reproduces it.
Churn rate = 100% - retention rate, and customers lost = customers at start - retained customers.
Implied lifespan = 1 / churn rate is the standard result for a constant per-period churn rate (a geometric lifetime). It is a modelling assumption, not something Shopify states; real churn is rarely constant, and it is left blank at 100% retention.
Define "customer" the same way at the start and the end (for example, bought within the last 12 months), or the rate will not mean anything.
Sources and basis (opened 2026-10-18): 14 Customer Retention Strategies for Ecommerce - Shopify. The retention rate formula and the 1,000 / 300 / 1,250 example are from the Shopify page. Churn, customers lost and implied lifespan are arithmetic on your inputs.
Inputs are user-entered figures. Results are planning estimates, not financial advice or a forecast of future performance. Everything runs in your browser. Nothing you type is sent or stored.
FAQ
How do you calculate customer retention rate?
Subtract new customers acquired from customers at the end, divide by customers at the start, and multiply by 100.
Why subtract new customers?
Because the goal is to measure how many of the customers you already had stayed. New customers at the end would otherwise inflate the rate.
What is churn rate?
It is the opposite of retention: 100% minus the retention rate, or the share of starting customers you lost.
What is a good customer retention rate?
This page does not publish industry benchmarks. Compare the result with your own earlier periods and segments. It depends heavily on whether your product is a subscription, a consumable or a one-off purchase.