With the illustrative inputs below, the result is 4 errors per month.
Try this with your own numbersFormula and worked example
Errors to prevent = ceiling(prevention cost / cost per error)
| Input | Example |
|---|---|
| Monthly prevention cost | 500 |
| Fully assigned cost per avoidable error | 125 |
| Calculated result | 4 errors per month |
Choose reliable inputs
Separate parts, technician time and bay availability for each repair order. For this auto detailing calculation, use repair orders, parts invoices and technician time logs and a consistent definition of one detail package.
- Consumables: include the portion belonging to this detail package or reporting period, and record where the value came from.
- Technician hours: include the portion belonging to this detail package or reporting period, and record where the value came from.
- Bay occupancy: include the portion belonging to this detail package 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 many errors must quality control prevent to pay?
Use avoidable cash or capacity costs. Do not count theoretical opportunity revenue as collected revenue.
What if this input changes?
If monthly prevention cost rises by 10%, this example changes by 1 errors per month. 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.