Free tool · 2026 UK rates
Renovation cost calculator
Pick a starting point, then change any activity, quantity or rate to match your own project. Contingency and VAT are added on top, and the total updates as you type. Nothing is saved and no account is needed.
Interactive · 2026 rates
Work out your own build cost
Single-storey rear extension, indicative 2026 rates.
| Activity | Quantity | Unit | Rate (£) | Cost | Remove |
|---|---|---|---|---|---|
| £13,000 | |||||
| £22,500 | |||||
| £9,500 | |||||
| £9,600 | |||||
| £6,500 | |||||
| £5,500 | |||||
| £4,500 | |||||
| £7,500 |
Rates are indicative UK averages for 2026. Change any figure to match quotes you have received.
- Works subtotal
- £78,600
- Contingency (10%)
- £7,860
- VAT (20%)
- £17,292
- Total estimated cost
- £103,752
How to use the numbers
- Measure the new or refurbished floor area in square metres.
- Set the quantities to your own areas, room counts and window numbers.
- Replace the rates with figures from quotes or from local builders as they come in.
- Keep contingency in the total — it is part of the budget, not a bonus.
- Add furniture, appliances and landscaping separately; they are not build costs.
Common questions
- How accurate is a renovation cost calculator?
- A calculator gives you an indicative budget, not a quote. Start with the 2026 rates here, then replace each rate with figures from your own quotes as they arrive. Expect a range of roughly 15% either side until you have priced drawings.
- How much contingency should I allow?
- Allow 10% on a straightforward new-build extension and 15–20% on works to an older house, where opening up reveals structure, damp or wiring you could not see.
- Do I pay VAT on a home renovation?
- Most home improvement work in the UK carries VAT at 20%. Some conversions and long-term empty properties qualify for a reduced rate, so check your position before assuming the full 20%.
Turn the estimate into a brief everyone can price
Renovome turns your figures into a defined scope, a realistic programme and a shortlist of matched professionals — so every quote prices the same job.