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.
Result
Base budget
Total budget with contingency
How to use this calculator
- Measure the area being renovated.
- Enter a cost per m² — the default is a rough mid-range figure; replace it with a real quote or local rate if you have one.
- Set a contingency percentage — 15% is a commonly recommended minimum for renovation work.
- Read the base budget and the total with contingency.
Assumptions
- The default £1,500/m² is a rough illustrative mid-range figure, not a quote — renovation costs vary hugely by region, property age and finish quality.
- Does not include VAT, professional fees (architect/structural engineer) or planning costs unless folded into your own cost-per-m² figure.
Technical details: what the fields mean
- Area being renovated
areaM2 - Floor area of the space being renovated.
- Cost per m² (check local quotes)
costPerM2Gbp - Cost per square metre — varies enormously by region, spec level and trade rates. Replace the default with a real quote wherever possible.
- 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: areaM2=40, costPerM2Gbp=1500, contingencyPercent=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.
- Older properties often need a higher contingency than 15%, especially if hidden issues (damp, wiring, structural) are possible.
Common mistakes
- Using a national average rate for a region with significantly higher or lower trade costs.
- Skipping the contingency allowance entirely — renovations very commonly run over initial estimates.
FAQs
How much does a 40m² renovation cost?
At a rough £1,500/m² with 15% contingency, about £69,000 — but get real local quotes, as rates vary hugely.
Does this include VAT and professional fees?
Not unless you fold them into your cost-per-m² figure — add them separately if relevant to your project.