Shared setup can reduce average variable cost, but a discount is only sustainable if the combined margin remains adequate.
Try this with your own numbersFormula and worked example
Bundle price = (items × variable cost + setup cost) / (1 − margin)
| Input | Example |
|---|---|
| Items or visits in bundle | 4 |
| Variable cost per item | 50 |
| One-time setup cost | 30 |
| Target contribution margin | 35 % |
| Calculated result | 353.8462 |
Choose reliable inputs
Account for delivery time, review work and when you expect to be paid for each engagement. For this bookkeeping service calculation, use time sheets, engagement scopes and invoice ageing and a consistent definition of one client month.
- Staff hours: include the portion belonging to this client month or reporting period, and record where the value came from.
- Software: include the portion belonging to this client month or reporting period, and record where the value came from.
- Review time: include the portion belonging to this client month 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.
Can a bundle reduce the cost per item?
Shared setup can reduce average variable cost, but a discount is only sustainable if the combined margin remains adequate.
This is a contribution-margin price; fixed business overhead is not automatically included.
What if this input changes?
If items or visits in bundle rises by 10%, this example changes by 30.7692 . 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.