- Define the cohort. Choose the clients who were actually eligible to return during the same follow-up period.
- Enter eligible clients. Count each client once rather than counting visits.
- Enter returning clients. Use only returned clients from that same cohort and time window.
- Check the retention rate. The main percentage is returned clients divided by eligible clients.
- Compare consistently. Keep your eligibility and follow-up definitions unchanged when comparing periods.
Sunscreen Use Client Retention Calculator
The Sunscreen Use Client Retention Calculator measures the share of eligible sunscreen-use program clients who returned during a defined follow-up window. It helps operators separate repeat-client performance from simple visit counts and gives a consistent percentage that can be compared across months, cohorts, or campaigns.
Use the same eligibility rule for the starting group and the returned group. The calculator also shows the number not retained and the corresponding churn percentage, making it easier to spot whether a change comes from a smaller cohort or from a real shift in repeat behavior.
Inputs
clients
clients
Result
—
The percentage is the share of eligible clients who returned within the defined follow-up window.
Returned clients—
Not retained—
Churn rate—
Eligible cohort—
Client retention rate (%) = (Clients who returned ÷ Clients eligible to return) × 100
Clients not retained = Eligible clients − Returned clients
Churn rate (%) = 100 − Retention rate
The returned count cannot exceed the eligible cohort when both values refer to the same measurement window.
What the result means
The percentage is the share of eligible clients who returned within the defined follow-up window.
Retention is only comparable when cohorts and time windows are defined consistently.
A seasonal sunscreen-use program had 180 clients who were eligible to return for the next cycle, and 126 of them returned.
Given: 180 eligible clients and 126 returning clients.
Calculation: (126 ÷ 180) × 100 = 70.0%. Not retained = 54.
Result: The cohort retention rate is 70.0%, with 30.0% not retained.
Given: 180 eligible clients and 126 returning clients.
Calculation: (126 ÷ 180) × 100 = 70.0%. Not retained = 54.
Result: The cohort retention rate is 70.0%, with 30.0% not retained.
Who belongs in the eligible-client count?
Include only clients who had a realistic opportunity to return within the follow-up window you selected. Excluding clients who are not yet due prevents the denominator from being artificially large.
Should repeat visits be counted more than once?
No. This calculator is client-based, so a returning person counts once even if that person had multiple visits during the window.
Can I compare retention across different months?
Yes, but the cohort definition and return window should stay consistent. A 30-day cohort and a 90-day cohort are not directly comparable without adjustment.
Why is the calculator rejecting a returned count above the eligible count?
For a single defined cohort, returned clients are a subset of eligible clients. A larger returned count usually means the two numbers were drawn from different populations or periods.
How is retention different from booking frequency?
Retention asks whether a client came back at all. Booking frequency measures how often retained clients visit, so the two metrics answer different operating questions.