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
Plan materials, travel and crew time before committing to a price. For this garage door service calculation, use a completed job sheet, supplier quotes and a crew schedule and a consistent definition of one repair visit.
- Parts: include the portion belonging to this repair visit or reporting period, and record where the value came from.
- Site time: include the portion belonging to this repair visit or reporting period, and record where the value came from.
- Vehicle overhead: include the portion belonging to this repair visit 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.