Site Coverage Calculator
Building footprint as a share of the site — the site coverage control in most planning schemes — with the impervious share, the footprint a limit allows, and the open space that is left.
Site coverage is the area under roof divided by the site area.
How the site coverage calculator works
Site coverage is the area under roof divided by the site area. Planning schemes cap it — often 50 to 60% for houses, higher in commercial zones — to keep gardens, drainage and daylight. The impervious share adds driveways and paving, and it is what stormwater rules look at.
The footprint the cap allows is the design brief in one number: on a 600 m² site at 50%, the house can be 300 m² on the ground and no more.
Formula: coverage = footprint / site; allowed footprint = site × limit
Worked examples
| Inputs | Site coverage | Note |
|---|---|---|
| 260 m² on a 600 m² site | 43.33% | 43% — complies |
| A bigger house | 55% | over the 50% limit |
| Lots of paving | 43.33% | coverage fine, impervious over |
FAQFrequently asked questions
What is site coverage?
The share of a site covered by buildings, measured at the ground. Most residential schemes cap it around 50 to 60%; commercial zones allow more.
What counts as footprint?
Usually anything under a roof — the house, a garage, a covered patio. Eaves and pergolas are often excluded. Check the definition in your scheme.
What is the impervious limit for?
Stormwater. Paving and roofs shed rain the ground would have absorbed, and the limit keeps runoff within what the drains were sized for.
Can I exceed the coverage limit?
Sometimes, with a variation, if the design meets the objectives another way. It is harder than staying under it.
Does a second storey count?
No — coverage is the ground footprint. A two-storey house of the same floor area halves its coverage, which is often the answer.
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
- Australian Building Codes Board — National Construction Code — the body that writes Australia's building code
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.