Cohort Retention Calculator
Track retention across periods for a cohort and find where users are lost.
About Cohort Retention Calculator
Retention is always measured against the original cohort size rather than the previous period, so the figures fall monotonically. What matters is whether the curve flattens, because a curve that flattens has found a group of users for whom the product works. The first period usually accounts for the largest loss, which makes onboarding the highest-leverage place to intervene rather than later-stage engagement.
Formula
Cohort Retention
Retention at period n = users still active ÷ original cohort size
- cohort
- A group of users who all joined in the same period
- flattening curve
- Losses shrinking each period, indicating a retained core
Worked example
With the default values below, Cohort Retention Calculator returns Retention After Period 3 of 25.000%. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Cohort size at signupminimum 1
- 1,200
- Still active after period 1minimum 0
- 540
- Still active after period 2minimum 0
- 372
- Still active after period 3minimum 0
- 300
Results
- Retention After Period 3
- 25.000%
- Retention After Period 1
- 45.000%
- Retention After Period 2
- 31.000%
- Period With the Largest Drop
- Period 1 — onboarding is where users are lost
- Curve Verdict
- Curve is flattening — a retained core is forming
Step by step
- 1Values used
- 2Cohort Retention
- 3Retention After Period 3= 25.000
- 4Retention After Period 1= 45.000
- 5Retention After Period 2= 31.000
- 6Period With the Largest Drop= Period 1 — onboarding is where users are lost
- 7Curve Verdict= Curve is flattening — a retained core is forming
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax or fees or charges into account.
- Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Cohort Retention calculated?
Retention at period n = users still active ÷ original cohort size Retention is always measured against the original cohort size rather than the previous period, so the figures fall monotonically. What matters is whether the curve flattens, because a curve that flattens has found a group of users for whom the product works.
Why does Cohort Retention matter?
The first period usually accounts for the largest loss, which makes onboarding the highest-leverage place to intervene rather than later-stage engagement.
What values do I need to enter?
This calculator takes 4 inputs: Cohort size at signup, Still active after period 1, Still active after period 2, Still active after period 3. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.