Customer cohort retention: practical guide

What to prepare

• Define the event, conversion, customer and attribution period before collecting data.
• Use spend and outcomes from the same reporting window.
• Distinguish revenue, contribution profit, recurring revenue and customer lifetime assumptions.

Understand the inputs

The calculation method

Retained original customers = ending customers − new customers. Retention = retained ÷ starting cohort.

Worked example

Illustrative inputs and their result.

Example inputs

Customers at period start

500

Customers at period end

540

New customers active at period end

80

Calculated example result

Retention Percent

92%

Churn Percent

8%

Net Customer Growth Percent

8%

How to interpret the result

A marketing metric depends on its attribution and cost definitions. A favourable ratio is not proof that advertising caused every sale or that future customers will behave the same way.

Compare campaigns with the same attribution window and outcome definition. Test a lower conversion rate or shorter retention period before extrapolating a promising result.

Common mistakes to avoid

• Do not double-count a customer or conversion reported by multiple channels.
• Revenue is not the same as profit available to fund acquisition.
• Small samples and changing cohorts can produce unstable comparisons.

Assumptions and sources

New customers must be active at period end; use cohort data when newly acquired customers also churn during the period.

Related sales & marketing guides

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• Email campaign performance: practical guide
• A/B conversion significance: practical guide
• Weighted sales pipeline: practical guide
• Progressive sales commission: practical guide