Renovation budget calculator
Most renovation budgets don't fail because one quote was wrong, but because of the things nobody priced: disposal of rubble, an extra socket, rotten floorboards discovered once the old floor is up. A budget that works lists every cost item and keeps a reserve for what can't be seen yet.
This tool contains no prices of its own — prices vary too much between countries, regions and years. Enter the amounts from your quotes, supplier prices or your own estimates; the calculator adds them up, applies the contingency and tells you whether the money is enough.
Your measurements
10% for a simple job, 15–20% for old buildings or when walls and pipes will be opened up.
Result
Enter at least one amount — from a quote, a supplier's price or your own estimate.
Amounts are in your currency. The tool contains no prices of its own: the result is only as good as the quotes you enter.
How the calculation works
- Sum of cost items = all the amounts you enter.
- Contingency reserve = sum × contingency percentage.
- Total budget = sum + reserve.
- Optional: cost per m² = total ÷ floor area; remaining or shortfall = available budget − total.
Worked example
Quotes of 4,000 for materials, 2,500 for labour and 1,500 for the electrical work add up to 8,000. A 15% reserve adds 1,200, so the budget to plan is 9,200. With 10,000 available, 800 is left over after the reserve.
What the calculator assumes
- The amounts are in whatever currency you enter; the calculator doesn't convert currencies.
- The default reserve is 15% — a common middle value between a simple job (10%) and work in an old building (20% or more).
When to adjust the result
- A budget is only as good as the quotes in it: compare quotes on the same scope of work (materials included or not, disposal, VAT).
- Leave the reserve untouched until the work is finished; using it for upgrades halfway through defeats its purpose.
- Large projects may involve design fees, permits or inspections that depend on local rules — ask your local authority what applies.
Frequently asked questions
How much contingency should a renovation budget have?
10% for simple, well-defined jobs; 15–20% for old houses or when walls, floors and pipes are opened up and hidden problems are likely. The less you know about the building, the higher the reserve.
What is most often forgotten in a renovation budget?
Waste disposal, protecting floors and furniture, small materials (fixings, sealants, primers), making good after the electrician or plumber, and the cost of living elsewhere during the work.
Why doesn't the calculator include prices?
Material and labour prices differ widely between countries and change every year. Built-in averages would look precise but could easily be wrong for you, so the tool works with your own figures.