How-To2026-09-0311 min read

How to Build a Cohort Analysis in Amplitude

Aggregate metrics hide the truth about your product's health. An overall 30-day retention rate of 40% might mean every cohort retains at exactly 40%, or it might mean early cohorts retain at 60% while recent cohorts retain at 20% — the same number with completely different implications. Cohort analysis reveals these patterns by grouping users based on when they joined or what they did, then tracking how their behavior evolves over time.

Amplitude's cohort analysis tools let you define cohorts by acquisition date, behavior, user properties, or any combination, then compare how these groups engage, retain, and convert. This guide shows you how to build meaningful cohort analyses that drive product decisions rather than just generating interesting charts.

Step-by-step guide

01

Define the cohort dimension and the metric you want to compare

Decide what you are comparing and how. The most common cohort dimension is signup week — grouping users by when they joined to see if retention is improving or declining over time. But you can also cohort by behavior (users who completed onboarding vs. those who did not), acquisition source, plan type, or any user property. Pair the cohort dimension with a specific metric: retention rate, feature adoption rate, or conversion rate.

  • Choose your cohort dimension: time-based (signup week/month) or behavior-based (action completed)
  • Select your measurement metric: retention, feature adoption, revenue, or conversion
  • Define the observation window — how many weeks or months you will track each cohort
02

Create a time-based retention cohort in Amplitude

Navigate to the Retention Analysis chart in Amplitude. Set the 'Starting Event' to signup_completed and the 'Return Event' to any core engagement event. Set the cohort grouping to 'By week' to create weekly signup cohorts. Amplitude will generate a retention table showing the percentage of each weekly cohort that returned in week 1, week 2, week 3, and beyond.

  • Select signup_completed as the starting event that defines when users enter each cohort
  • Choose your most meaningful engagement event as the return event — not just login, but a value-delivering action
  • Set the retention type to 'Unbounded' for overall return rate or 'N-day' for day-specific retention curves
03

Build a behavioral cohort to compare user segments

Go to the Cohorts section in Amplitude and create a new behavioral cohort. Define the cohort by a specific action — for example, 'users who invited at least one teammate within 7 days of signup.' Create a comparison cohort of users who did not complete that action. Apply both cohorts to a retention chart to see the dramatic difference in retention between the two groups.

  • Define the behavioral cohort using the cohort builder: performed [event] [N] times in [time window]
  • Create the complementary cohort: users who did NOT perform the same event in the same window
  • Apply both cohorts as segments on the same retention or engagement chart for side-by-side comparison
04

Analyze cohort curves to find retention drivers

Compare the retention curves of your behavioral cohorts. If users who completed onboarding retain at 50% after 8 weeks while those who skipped it retain at 15%, onboarding completion is a strong retention driver. Look for the 'flattening point' in each cohort's curve — the week where retention stabilizes — and compare where it flattens and at what level across segments.

  • Identify which behavioral cohorts have the highest retention floor (the level where the curve flattens)
  • Calculate the absolute retention difference between cohorts at key time points (week 1, week 4, week 8)
  • Rank behavioral cohort differences by magnitude to prioritize which behaviors to drive in onboarding
05

Create a cohort comparison dashboard

Build a dashboard in Amplitude that shows your key cohort comparisons at a glance. Include a weekly cohort retention table to track retention trends over time, a behavioral cohort comparison chart showing your top retention drivers, and a conversion funnel segmented by your most impactful cohort dimensions. This dashboard becomes the reference for product strategy discussions about retention and engagement.

  • Add a retention table showing the last 12 weekly signup cohorts with color-coded cells
  • Include a behavioral cohort comparison chart with your top 3 retention-driving behaviors
  • Add a trend line showing the week-4 retention rate for each signup cohort over the last 6 months
06

Act on cohort insights by targeting interventions

Sync your behavioral cohorts to your engagement tools (email, push notifications, in-app messaging) to target interventions at users who have not yet completed the retention-driving behavior. For example, if completing onboarding is the strongest retention driver, sync the 'signed up but did not complete onboarding within 48 hours' cohort to your email tool and trigger a re-engagement campaign automatically.

  • Sync at-risk cohorts to Braze, Iterable, or your messaging platform via Amplitude's integrations
  • Create targeted interventions for each retention-driving behavior that at-risk users have not completed
  • Track whether the intervention improves the behavioral cohort distribution over subsequent weeks

Common mistakes

Comparing cohorts of very different sizes

A cohort of 50 users behaving differently from a cohort of 5,000 might just be noise. Always check cohort sizes and apply minimum sample size thresholds before drawing conclusions. Amplitude shows cohort sizes in the retention table — use them.

Using login as the return event for retention

Login does not equal engagement. A user who logs in to check their billing page and then leaves is counted as retained. Use a value-delivering event (created a report, sent a message, completed an analysis) as your return event to measure meaningful retention.

Ignoring the maturation period of recent cohorts

The most recent weekly cohort always looks bad because users have not had enough time to return. Do not panic about the latest cohort's low numbers — compare cohorts at the same maturity point (e.g., compare all cohorts at their week-4 mark, not their current mark).

Tips

Use Amplitude's Compass feature to automatically identify the events most correlated with retention, then build cohorts around those events

Create a monthly email report from your cohort dashboard and send it to the product leadership team so retention trends stay visible

Combine time-based and behavioral cohorts — for example, track onboarding completion rate for each weekly signup cohort to see if product changes improve activation over time

Export cohort data to a spreadsheet for custom analyses like LTV by cohort or payback period by acquisition source

How Vantage helps

Vantage helps PMs turn cohort analysis insights into product changes. When your Amplitude data reveals that a specific behavior drives retention, Vantage captures that insight as a requirement and generates the implementation plan to make that behavior easier, more discoverable, or part of the default onboarding flow.

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