In this example, increasing revenue per installation from 800 to 880 changes the result from 325 to 405 . All other inputs stay the same.
Try this with your own numbersFormula and worked example
Contribution = price − materials − hours × labour cost − other variable cost
| Input | Example |
|---|---|
| Revenue per installation | 800 |
| Materials or purchased services | 250 |
| Delivery labour hours | 5 |
| Burdened hourly labour cost | 35 |
| Other variable cost | 50 |
| Calculated result | 325 |
Choose reliable inputs
Plan materials, travel and crew time before committing to a price. For this solar installation calculation, use a completed job sheet, supplier quotes and a crew schedule and a consistent definition of one installation.
- Equipment: include the portion belonging to this installation or reporting period, and record where the value came from.
- Subcontract work: include the portion belonging to this installation or reporting period, and record where the value came from.
- Site access: include the portion belonging to this installation 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.
Is contribution the same as net profit?
Contribution still needs to cover rent, management, software, and other fixed costs before there is net profit.
Include variable costs only here; fixed overhead is not deducted.
What if this input changes?
If revenue per installation rises by 10%, this example changes by 80 . 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.