Cost Per Square Meter Calculator
Construction cost from floor area and a rate per square meter — or the rate a budget implies — with the on-costs that turn a build rate into a project cost.
A build rate covers the building.
How the cost per square meter calculator works
A build rate covers the building. The project costs more: professional fees of 10 to 15%, a contingency of 5 to 10%, and authority charges. Multiplying the rate by the area and stopping there is the most common way a budget is set wrong.
The reverse calculation is the useful one when the budget is fixed: strip the on-costs off, divide by the area, and see whether the rate that is left buys the building you have drawn.
Formula: project cost = area × rate × (1 + fees + contingency)
Worked examples
| Inputs | Project cost | Note |
|---|---|---|
| 320 m² at 3,200 | 1,228,800 | about 1.23 million as a project |
| A tighter budget | 1,228,800 | the rate it allows |
| No on-costs | 1,024,000 | the build cost alone |
FAQFrequently asked questions
What does it cost to build per square meter?
It varies enormously by market, quality and building type — from under 2,000 to well over 6,000 for houses. Use a current local cost guide, and remember the rate is the building only.
What are on-costs?
Everything the build rate leaves out — design and engineering fees, authority charges, surveys, and a contingency for what nobody foresaw. Twenty to thirty per cent on top is normal.
How much contingency?
Five per cent for a simple new build with good documentation; ten or more for renovation, where the unknowns live in the walls.
Why work backwards from the budget?
Because the budget is usually fixed and the design is not. The rate the budget allows tells you what quality of building you can afford before you draw it.
Is the all-in rate the number to quote?
It is the honest one. A build rate quoted without on-costs is how a client ends up 25% over before construction starts.
Where these figures come from
- Sabine (1922) — Collected Papers on Acoustics — the reverberation-time equation
- CIBSE Guide A — Environmental design — daylight, comfort and ventilation criteria
- Neufert — Architects' Data — the standard reference for space and dimension
- International Code Council — International Building Code — occupant load and egress factors
- International Code Council — publisher of the model codes most US jurisdictions adopt
Last checked: September 2026. Formulas are the standard building-science and code relationships; default thresholds are common international values and should be replaced with the ones in your code.