Unpriced changes consume labour and materials without raising revenue. Record the extra scope and obtain agreement before using a quote.
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
Include software licences, delivery time, revisions and ongoing support when costing a project. For this web design calculation, use project time logs, licence invoices and retainer scopes and a consistent definition of one project.
- Design hours: include the portion belonging to this project or reporting period, and record where the value came from.
- Development: include the portion belonging to this project or reporting period, and record where the value came from.
- Revisions: include the portion belonging to this project 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.