Construction Cost Estimator
Get a ballpark budget for a build or renovation from the floor area and a cost per square metre, with a contingency allowance for the surprises every project springs. A planning figure — not a quote.
How to use this calculator
- Enter the floor area per floor and the number of floors.
- Enter a cost per m² for your region and finish level (from local sources or a builder).
- Keep a contingency of 10–20% — renovations especially uncover surprises.
Formula used
Cost per m² is the crucial and most variable input — it ranges enormously by country, city, finish quality and project type (a basic build vs a high-spec renovation can differ several-fold). This gives an order-of-magnitude budget, not a quote.
Example calculation
A 100 m² single-floor build at 15,000/m² with 15% contingency: 100 × 15,000 = 1,500,000 base + 225,000 contingency = ~1,725,000.
That works out to 17,250/m² all-in — the number to sanity-check against local build costs.
Using a per-m² estimate wisely
Cost-per-square-metre is how the construction industry sizes budgets early, before detailed drawings exist. It's genuinely useful for feasibility — deciding whether a project is roughly affordable — but it's an average that hides enormous variation: the rate depends on location, specification, structural complexity, site access and market conditions, and a figure from one project can mislead badly on another.
The contingency is the part amateurs underestimate. Renovations in particular uncover hidden problems (rot, wiring, drainage, structural surprises) once work begins, and prices for materials and labour shift. Professionals carry 10–20% contingency as standard; treating the base estimate as the final budget is how projects run over. Use this figure to start conversations with builders, not to replace their quotes.
Why use this calculator?
- Get an order-of-magnitude budget before commissioning drawings.
- Build in the contingency that real projects always need.
- See the all-in per-m² rate to compare against local benchmarks.
Frequently asked questions
How much does it cost to build per square metre?
It varies enormously by country, region, finish level and project type — there's no universal figure. Get local build-cost benchmarks or a builder's rate for your area and specification, then use this tool to scale it to your floor area.
How much contingency should I budget?
10–15% for new builds with clear scope, 15–20%+ for renovations and older buildings where hidden problems are likely. Contingency covers surprises and price changes; projects that skip it routinely overrun.
Is this a reliable quote?
No — it's a planning estimate to gauge feasibility and scale. Real costs depend on detailed design, site conditions, permits, professional fees and current market rates. Always obtain itemised quotes from builders before committing funds.