Zoning Yield Calculator
How many lots or dwellings a site yields once roads, open space and minimum lot sizes are taken out — the number a developer's first feasibility runs on.
Gross site area loses a share to roads and reserves, and another to public open space.
How the zoning yield calculator works
Gross site area loses a share to roads and reserves, and another to public open space. What remains is net developable area, divided by the minimum lot size — or multiplied by a dwellings-per-hectare rate for apartment zones.
The road and open-space deductions are the numbers that decide feasibility. Twenty-five per cent for roads and ten for open space is common; getting the local figures is worth more than any other refinement.
Formula: net area = gross × (1 − roads − open space); lots = net / min lot size
Worked examples
| Inputs | Lots | Note |
|---|---|---|
| 12 ha at 450 m² lots | 173 | 173 lots |
| Smaller lots | 260 | 260 lots |
| Townhouses | 130 | fewer lots, more dwellings |
FAQFrequently asked questions
How much of a site goes to roads?
Twenty to thirty per cent in conventional subdivision. Smaller lots and denser layouts push it higher, because there are more frontages to serve.
What is net developable area?
The gross site less roads, reserves, drainage and public open space. It is the land that actually becomes lots.
Why round lots down?
Because a fraction of a lot is not a lot. In practice the layout loses a few more to odd shapes at the edges.
What is a typical dwellings-per-hectare?
Twelve to fifteen per gross hectare for detached housing, 25 to 40 for townhouses, and 80 or more for apartments.
Does this replace a feasibility study?
No — it is the first arithmetic in one. Slope, drainage, overlays and access can all take further land.
Where these figures come from
- UN-Habitat — Urban Indicators Guidelines — density, green space and public space benchmarks
- World Health Organization — Urban green spaces — the 9 m² per person minimum
- ITE — Parking Generation Manual — parking demand rates by land use
- Office for National Statistics — Population estimates — the UK's national statistics agency
Last checked: September 2026. Default per-capita rates are mid-range figures from national statistical agencies and utility reports; every one is an input you should replace with the local figure.