Free tool
Renovation budget calculator
Add up build cost, professional fees, statutory costs and living expenses, then apply a contingency percentage to see the total commitment behind a headline quote.
Step 1
Enter what you know so far
Leave anything blank that does not apply — figures are illustrative and user-entered, not a valuation of your project.
10–15% is a common starting point on a straightforward renovation. Move it higher for the reasons set out below.
Step 2
Your total likely commitment
| Item | Amount |
|---|---|
| Build cost (main contract) | £40,000 |
| Professional fees (architect, structural engineer) | £2,000 |
| Surveys (structural, drainage, party wall) | £800 |
| Statutory fees (planning, Building Control) | £600 |
| Decoration after handover | £1,500 |
| Subtotal | £44,900 |
| Contingency (12%) | £5,388 |
| Total likely commitment | £50,288 |
Guidance
When a larger contingency is sensible
Consider moving towards 15–20% or higher, rather than the 10% default, if any of the following apply to your project:
- The property is older, with solid walls, unknown foundations or historic alterations
- The works involve opening up existing structure before the true condition is known
- Drainage runs, cabling or pipework locations are not confirmed
- The project depends on planning conditions or party wall agreement
A contingency is not a discretionary extra — treat it as committed money until the job is finished. Keeping it separate from your everyday account makes it harder to spend accidentally.
For the payment side of the same budget, use the stage payment planner and read how much deposit you should reasonably pay.
Comparing quotes for this project?
Have a look at whether each quote is priced on the same scope.
Builder Proof UK publishes general educational information for homeowners. It is not legal, structural, surveying, planning, electrical, gas, insurance or financial advice, and it does not replace advice from a suitably qualified professional for your specific project.