With the illustrative inputs below, the result is 90 %.
Try this with your own numbersFormula and worked example
Retention = (ending customers − new customers) / starting customers × 100
| Input | Example |
|---|---|
| Active customers at period start | 200 |
| Active customers at period end | 220 |
| New customers during period | 40 |
| Calculated result | 90 % |
Choose reliable inputs
Account for turnaround, maintenance and available inventory before accepting another booking. For this storage operator calculation, use rental contracts, asset records and maintenance logs and a consistent definition of one unit rental.
- Facility overhead: include the portion belonging to this unit rental or reporting period, and record where the value came from.
- Vacancy: include the portion belonging to this unit rental or reporting period, and record where the value came from.
- Service costs: include the portion belonging to this unit rental or reporting period, and record where the value came from.
Use the same currency for every money input. Do not mix weekly costs with monthly revenue, or count the same expense in both an itemised cost and allocated overhead.
Why subtract new customers from the ending count?
New acquisitions can hide losses in the starting cohort. Retention should track existing customers separately.
Assumes consistent active-customer definitions and no reactivations counted separately.
What if this input changes?
If active customers at period start rises by 10%, this example changes by -8.1818 %. This shows the effect of one change; it does not predict what will happen.
Open the calculator, save your baseline, then change the input supported by the least reliable estimate in your records. Compare both scenarios before committing to a price or capacity promise.