Retention rate measures the share of an opening customer base that remains. Churn rate measures the share that leaves. They equal 100% complements only when they use the same customer population, period, status rules and event treatment.
Customer retention and churn formulas
A common customer retention formula removes customers acquired during the period from the ending count.
retention rate = (ending customers - new customers) / starting customers × 100A common customer churn formula divides customers lost during the period by customers present at the start.
customer churn rate = customers lost / starting customers × 100These are the definitions used by the retention rate calculator and churn rate calculator. Stripe documents the same basic customer-count approach, while also emphasizing that the business must define what counts as a customer and a loss.
Worked reconciliation example
Suppose a subscription business starts April with 1,000 active customers. During April, 80 of those customers leave, 120 new customers join and no churned customer reactivates before month-end.
- Ending customers:
1,000 - 80 + 120 = 1,040 - Retained opening customers:
1,040 - 120 = 920 - Retention rate:
920 / 1,000 = 92% - Churn rate:
80 / 1,000 = 8%
In this controlled example, retention plus churn equals 100%. The acquisition of 120 new customers changes the ending total but not the opening cohort’s retention rate.
When retention plus churn does not equal 100%
Real dashboards often use definitions that break the simple relationship.
| Reporting choice | Effect on the relationship |
|---|---|
| Reactivated customers counted as retained | Retention can rise without reversing the original churn event |
| Churn based on cancellation date, retention based on paid-through date | Events fall into different periods |
| Retention based on active users, churn based on paying accounts | Numerators and denominators describe different units |
| Revenue retention includes expansion | Net revenue retention can exceed 100% |
| Grace-period customers remain active | Churn recognition is delayed |
| Trial users included in one metric only | The eligible population changes |
Do not force the metrics to reconcile by adjusting a formula after the fact. Make the scope explicit and calculate each measure from a consistent event table.
Customer churn is not revenue churn
Customer churn gives every customer equal weight. Revenue churn weights lost recurring revenue. Losing one large account can produce low customer churn and high revenue churn.
Assume a business starts with 100 customers and $100,000 in monthly recurring revenue. Two customers churn:
- one pays $500 per month;
- one pays $9,500 per month.
Customer churn is 2 / 100 = 2%. Gross revenue churn is $10,000 / $100,000 = 10%. Both calculations are correct, but they answer different questions.
Net revenue retention also includes expansion and contraction among retained customers.
net revenue retention = (starting revenue - churn - contraction + expansion) / starting revenue × 100Because expansion is included, net revenue retention can exceed 100%. That does not mean no customers churned.
Choose the correct denominator
The denominator should contain only units that were genuinely at risk of churning during the period. For monthly customer churn, that normally means customers active at the start of the month. New customers acquired halfway through the month had less exposure time and should not simply be added to the opening denominator.
Define these rules before calculating:
- What is the unit: person, subscription, account, location or recurring revenue?
- When does a customer become active?
- What event counts as churn: cancellation request, service end, failed payment or inactivity?
- How is a reactivation treated?
- Are pauses, free plans and delinquent accounts active?
- What timezone and period boundary does the report use?
If two teams use different answers, they are not reporting the same metric even if both labels say “churn.”
Period rates cannot be compared casually
A monthly churn rate should not be multiplied by 12 and presented as an annual rate without stating the approximation. Under a constant monthly churn assumption, survival compounds.
annual retention = (1 - monthly churn)¹²At 5% monthly churn, the simplified annual retention estimate is 0.95¹² = 54.0%, so annual churn is approximately 46.0%. Multiplying 5% by 12 would produce 60%, which ignores the shrinking population. The constant-rate assumption may still be unrealistic when tenure, contracts or seasonality change behavior.
Cohorts explain what a blended rate hides
A blended monthly rate combines customers acquired at different times and under different offers. Build acquisition cohorts when you need to understand product changes or onboarding quality.
| Cohort | Start | Active after month 1 | Month 1 retention | Active after month 3 | Month 3 retention |
|---|---|---|---|---|---|
| January | 200 | 170 | 85% | 142 | 71% |
| February | 240 | 216 | 90% | 185 | 77.1% |
The February cohort shows better survival at both checkpoints. A blended active-customer total could hide that improvement if the business simultaneously changed acquisition volume.
Connect retention to customer value carefully
Simple lifetime-value models sometimes approximate customer lifetime as 1 / churn rate. That shortcut assumes a stable, memoryless churn process and consistent periods. It becomes unreliable when churn changes by tenure, contracts renew annually or customer mix shifts. Use the customer lifetime value calculator for a transparent simple model, then compare it with cohort evidence before using it for acquisition decisions.
Reporting checklist
- Put the metric unit and period in the title.
- Show the formula beside the number.
- Record the opening population and all movements.
- Separate customer, gross revenue and net revenue measures.
- Keep cancellation, service-end and payment-failure dates distinct.
- Publish cohort views alongside the blended rate.
- Reconcile the customer movement equation before interpreting changes.
Retention and churn are most useful when they describe a precisely defined population. The formula is the easy part. The operating definition determines whether the result can support a decision.
Sources
- Stripe: retention rate vs churn rate; Stripe; accessed Jul 13, 2026
- Stripe: how to calculate churn rates; Stripe; accessed Jul 13, 2026
This guide is educational and does not provide financial, accounting, tax or legal advice.