In this example, increasing extra labour hours from 6 to 6.6 changes the result from 560 to 592 . All other inputs stay the same.
Try this with your own numbersFormula and worked example
Extra quote = (hours × hourly cost + materials + fees) / (1 − margin)
| Input | Example |
|---|---|
| Extra labour hours | 6 |
| Burdened labour cost per hour | 40 |
| Extra materials | 150 |
| Other extra cost | 30 |
| Target margin | 25 % |
| Calculated result | 560 |
Choose reliable inputs
Account for delivery time, review work and when you expect to be paid for each engagement. For this legal practice calculation, use time sheets, engagement scopes and invoice ageing and a consistent definition of one matter.
- Professional time: include the portion belonging to this matter or reporting period, and record where the value came from.
- Filing expenses: include the portion belonging to this matter or reporting period, and record where the value came from.
- Admin support: include the portion belonging to this matter 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 should extra work be priced separately?
Unpriced changes consume labour and materials without raising revenue. Record the extra scope and obtain agreement before using a quote.
This excludes contractual requirements and the original job price.
What if this input changes?
If extra labour hours rises by 10%, this example changes by 32 . 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.