📈 Metrics

Retention & cohorts

Track groups who joined at the same time to see who sticks around.

Formula

Retention (month n) = Active users from cohort in month n ÷ Cohort size

A cohort is a group of users who started in the same week or month. Retention shows what share are still active over time.

Cohorts reveal whether the product is getting better: newer cohorts should retain better than older ones.

🧮 Example

Of 1,000 users who joined in January, 350 are active in April → month-3 retention = 35%.

🎯 Interview tip

A retention curve that flattens means you've found loyal users; one that keeps falling to zero means product problems.

Used in

Learn next

Churn

The share of customers who leave in a period.

Lifetime value (LTV)

The total profit a customer brings before they leave.

Funnel analysis

Find the stage where customers drop off.

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