In this example, increasing purchased material cost from 1,000 to 1,100 changes the result from 11.1111 per usable unit to 12.2222 per usable unit. All other inputs stay the same.
Try this with your own numbersFormula and worked example
Cost per usable unit = purchase cost / (purchased units × usable share)
| Input | Example |
|---|---|
| Purchased material cost | 1,000 |
| Purchased units | 100 |
| Usable share | 90 % |
| Calculated result | 11.1111 per usable unit |
Choose reliable inputs
Allow time for preparation, the service itself and cleaning up before the next appointment. For this spa calculation, use appointment history, service durations and supply costs and a consistent definition of one appointment.
- Staff time: include the portion belonging to this appointment or reporting period, and record where the value came from.
- Consumables: include the portion belonging to this appointment or reporting period, and record where the value came from.
- Room occupancy: include the portion belonging to this appointment 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 is purchase price per unit below usable cost?
Yield must be greater than zero. Keep purchased and usable quantities in the same measurement unit.
What if this input changes?
If purchased material cost rises by 10%, this example changes by 1.1111 per usable unit. 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.