Model the months with low collections and unavoidable cash expenses. Update the assumptions with your own seasonal records.
Try this with your own numbersFormula and worked example
Reserve = months × max(0, fixed costs − cash contribution) + buffer
| Input | Example |
|---|---|
| Low-season months | 3 |
| Monthly fixed cash costs | 8,000 |
| Monthly cash contribution in low season | 5,000 |
| Extra contingency cash | 3,000 |
| Calculated result | 12,000 |
Choose reliable inputs
Separate parts, technician time and bay availability for each repair order. For this tire shop calculation, use repair orders, parts invoices and technician time logs and a consistent definition of one service order.
- Tires: include the portion belonging to this service order or reporting period, and record where the value came from.
- Consumables: include the portion belonging to this service order or reporting period, and record where the value came from.
- Fitting labour: include the portion belonging to this service order 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.
How should seasonal reserves be estimated?
Model the months with low collections and unavoidable cash expenses. Update the assumptions with your own seasonal records.
Assumes the same monthly shortfall; use cash contribution rather than invoice profit.
What if this input changes?
If low-season months rises by 10%, this example changes by 900 . 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.