Retail Floorspace Demand Calculator
How much retail floor space a catchment can support — from population, spending per person, the share captured locally, and the sales each square metre needs to be viable.
Supportable floor space is total spend captured divided by the sales density a shop needs to survive.
How the retail floorspace demand calculator works
Supportable floor space is total spend captured divided by the sales density a shop needs to survive. Population times spend per head gives the pot; the capture rate says how much stays local rather than leaking to a bigger centre; dividing by a viable turnover per square metre gives the area.
The capture rate is the number that matters and the one most often overstated. A neighbourhood centre rarely captures more than 30 to 40% of its catchment's spend.
Formula: floorspace = population × spend × capture / sales density
Worked examples
| Inputs | Supportable floorspace (m²) | Note |
|---|---|---|
| 24,000 people, 35% capture | 12,277 | about 12,300 m² |
| Low capture | 5,262 | a big centre nearby |
| A growing catchment | 18,415 | room for more |
FAQFrequently asked questions
What is a viable sales density?
The turnover per square metre a shop needs to cover rent, wages and margin. Supermarkets need 8,000 to 12,000 a year; specialty retail 4,000 to 7,000.
What capture rate should I assume?
A neighbourhood centre captures 25 to 40% of its catchment's spend; a regional mall 60% or more. Overstating it is the classic error.
How much do people spend on retail?
Around 8,000 to 12,000 a year per person in developed economies, including groceries. Use your national household expenditure survey.
What does a positive gap mean?
That the catchment could support more shops than exist — a case for a development, or evidence that spend is leaking elsewhere.
Does online shopping change this?
It reduces the share of spend that reaches any physical centre. Trim the spend figure by the online share for your category.
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
- Australian Bureau of Statistics — Regional population — Australia'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.