Customer Retention Rate Explained: How to Calculate It Without Hiding the Problem
Customer retention rate tells you what percentage of an existing customer base remained active over a period after excluding newly acquired customers.
Shopify’s formula is:
(Customers at end − new customers acquired) ÷ customers at start × 100. (shopify.com)
Simple.
But the period matters enormously.
Choose a window that fits the product
A weekly grocery business and furniture retailer should not use the same interpretation.
If the normal purchase cycle is 30 days, annual retention may hide too much.
If the natural cycle is 18 months, monthly retention may be meaningless.
Cohort retention is often more useful
Instead of:
What percentage of all customers stayed?
Ask:
What percentage of January’s customers bought again by month three?
Shopify’s current cohort tools use this approach because blended averages can hide deterioration in newer customers. (shopify.com)
Retention and repeat purchase are not identical
A customer can buy twice and still not be considered “retained” under a longer-term definition.
Define the metric clearly.
Churn is the inverse only in simple models
For subscription populations:
Retention + churn often equals 100%.
For ecommerce purchase cohorts, “retention” definitions vary, so do not assume the relationship automatically.
Frequently asked questions
What is a good ecommerce retention rate?
It depends on the category and time horizon. Consumables should retain differently from durable goods.
Is 80% retention good?
Without the period and product model, the number has little meaning.
How do I improve retention rate?
Find the stage or cohort where retention breaks before selecting tactics.
The rule
A retention rate without a time window and customer definition is not a metric.
It is a number.