Definition
Cohort age is how long a cohort has existed since start. Older cohorts often behave differently than new cohorts due to mix and lifecycle effects.
Example
A cohort that started in January is at cohort age month 6 in June.
How to use it
- Use cohort age to interpret why churn and expansion change over time.
- Avoid comparing cohorts without accounting for product and pricing changes.
- Compare cohorts at the same age to avoid maturity bias.
- Track cohort age when forecasting retention or expansion benchmarks.
Common mistakes
- Comparing cohorts with different ages as if they are equivalent.
- Ignoring major product changes that shift cohort behavior.
- Mixing calendar time with cohort time in the same chart.
Measured as
Measure Cohort Age on the same customer segment, time window, and revenue basis each time you review it.
Misused when
- Comparing cohorts with different ages as if they are equivalent.
- Ignoring major product changes that shift cohort behavior.
- Mixing calendar time with cohort time in the same chart.
Operator takeaway
- Use cohort age to interpret why churn and expansion change over time.
- Avoid comparing cohorts without accounting for product and pricing changes.
- Compare cohorts at the same age to avoid maturity bias.
- Keep Cohort Age consistent by cohort, segment, and period before you use it as a decision signal in planning or reporting.
- Interpret the metric alongside retention, margin, or payback so one ratio does not hide the real operating trade-off.
Next decision
- Read Cohort analysis playbook: retention curves, LTV forecasting, and payback if the decision depends on interpretation, policy, or trade-offs beyond the raw formula.
- Decide whether Cohort Age is a growth, retention, or efficiency signal before you set targets around it.
Where to use this on MetricKit
Guides
- Cohort analysis playbook: retention curves, LTV forecasting, and payback: A practical cohort analysis workflow: build retention curves, forecast LTV, and translate retention quality into payback and growth decisions.