Renovation budget estimator

Get a rough renovation budget from the area being worked on and a cost-per-square-metre rate, with a contingency allowance for the unexpected.

Area being renovated (m²)Cost per m² (check local quotes) (£/m²)Contingency (%)

Result

Base budget

Total budget with contingency

How to use this tool

Measure the area being renovated.
Enter your own cost per m² if available. The prefilled £1,500/m² is an adjustable illustration only, not a current market rate or quote.
Set a contingency percentage — the Federation of Master Builders suggests at least 10%, and 15% or more for older homes or structural work.
Read the base budget and the total with contingency.

The prefilled £1,500/m² is an adjustable arithmetic example, not a published or user-supplied market rate. General renovation scope varies too much for one rate to represent a reliable quote.
The default 15% contingency is an editable scenario input, not a recommendation for every project. Choose a contingency that reflects the work and uncertainties in your own project.
The calculation includes only area × the rate you enter, plus the contingency percentage. Check whether the rate includes VAT, professional fees, approvals, surveys, utility/service work and temporary accommodation; these are not added separately.

Technical details: what the fields mean

Area being renovated areaM2: Floor area of the space being renovated.
Cost per m² (check local quotes) costPerM2Gbp: Your cost assumption per square metre. The prefilled value is illustrative; actual rates vary by scope, region and specification, so use a comparable local quote.
Contingency contingencyPercent: Extra budget held back for unexpected issues — common in older properties especially.

Methodology

Base budget = area × cost per m². Total = base budget × (1 + contingency%).

Worked example

40m² renovation at £1,500/m², 15% contingency

Inputs: Area being renovated: 40 m², Cost per m² (check local quotes): £1500/m², Contingency: 15%

Result: £60,000 base, £69,000 with contingency

Practical guidance

Get at least 2–3 real quotes before finalising a budget — this tool is a starting-point estimate, not a substitute for one.
For a scope check, list the work included in your area-and-rate estimate alongside possible costs outside it, such as VAT, professional fees, approvals, surveys, service changes and accommodation.

Common mistakes

Using a national average rate for a region with significantly higher or lower trade costs.
Assuming the rate covers costs such as VAT, fees or temporary accommodation without checking the quote scope.

Not unless you fold them into your cost-per-m² figure — add them separately if relevant to your project.

Last reviewed: 2026-10-11

A rough starting-point estimate only, not a quote. This is not financial or investment advice.

This tool provides an indicative estimate, based on the assumptions stated above.

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