Definition
Cohort month is the month index of a cohort relative to its start (month 0, month 1, month 2...). It is used to align retention curves.
Example
A cohort that started in March is in cohort month 2 in May, even if the calendar month is different.
How to use it
- Use cohort month to compare curves across different start dates.
- Report both cohort month and calendar month to avoid confusion.
- Keep the same cohort definition (signup vs first value) across reports.
Common mistakes
- Mixing cohorts defined by different start events.
- Comparing cohort month 1 in one report to calendar month 1 in another.
Measured as
Measure Cohort Month on the same customer segment, time window, and revenue basis each time you review it.
Misused when
- Mixing cohorts defined by different start events.
- Comparing cohort month 1 in one report to calendar month 1 in another.
Operator takeaway
- Use cohort month to compare curves across different start dates.
- Report both cohort month and calendar month to avoid confusion.
- Keep the same cohort definition (signup vs first value) across reports.
- Keep Cohort Month 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 Month 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.