With the illustrative inputs below, the result is 33.3333 hours per month.
Try this with your own numbersFormula and worked example
Available hours = (retainer × (1 − margin) − other delivery costs) / hourly cost
| Input | Example |
|---|---|
| Monthly retainer fee | 3,000 |
| Non-labour monthly delivery cost | 300 |
| Target contribution margin | 40 % |
| Loaded delivery hourly cost | 45 |
| Calculated result | 33.3333 hours per month |
Choose reliable inputs
Include software licences, delivery time, revisions and ongoing support when costing a project. For this it support calculation, use project time logs, licence invoices and retainer scopes and a consistent definition of one support ticket.
- Technician time: include the portion belonging to this support ticket or reporting period, and record where the value came from.
- Software: include the portion belonging to this support ticket or reporting period, and record where the value came from.
- Escalation work: include the portion belonging to this support ticket 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 hours can a retainer support?
A negative answer means other costs already exceed the chosen cost envelope. Fixed overhead is not included unless entered.
What if this input changes?
If monthly retainer fee rises by 10%, this example changes by 4 hours 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.