Erf size and property size lookup: how to check erf details before you buy

"About a thousand squares." "Quarter acre." "Big stand." Property is described loosely, and bought precisely. The registered erf size is the number that the municipality rates, the bank lends against, and the town planner uses to work out what may be built.

A property size lookup takes a minute and regularly disagrees with the advert.

What erf size means

Erf size, or extent, is the surveyed area of the land parcel as recorded on the approved survey diagram or general plan and in the title deed. It is expressed in square metres, or in hectares for larger properties (1 hectare = 10,000 m²).

It is a legal fact about the land. It does not change because a fence was moved or a garden extended onto the pavement.

Erf size is not house size

Three different areas get confused:

• Erf size — the land.
• Floor area — the total area of the buildings across all storeys.
• Coverage — the footprint of the buildings on the land.

A listing that says "450 m²" might mean any of them. Ask which. The relationship between them is what planning controls regulate; see floor area ratio, coverage and height restrictions.

For a sectional title unit, the relevant figure is the section's floor area and its participation quota in the scheme, not an erf size. See freehold versus sectional title.

How to do a property size lookup

1. Search the address or erf number on checkproperty.co.za.
2. Open the property. The summary shows the erf size along with the erf number, township and zoning label.
3. Compare the boundary on the map with what you saw on site.

The property report adds the rest of the erf details: the municipal valuation, sales history, comparable sales and site constraints. The Development potential report adds zoning detail, title and survey information.

If you only have an address, the search finds the erf for you. See erf number lookup.

The erf details worth reading together

Erf number and township. The legal identity.

Erf size. The registered extent.

Zoning. What the land may be used for. See zoning check.

Municipal valuation. What the City values the property at for rates. See municipal valuation vs market value.

Suburb, ward and region. The administrative context. See ward, region and council data.

Boundary. The shape, which matters as much as the area.

Why erf size matters

Price

Land value is frequently compared per square metre. Knowing the true erf size lets you compare one property with another on the same basis. A house on 1,500 m² and a similar house on 900 m² are not the same purchase, even at the same price.

Development yield

Density, floor area and coverage are all calculated from erf size. A 10% error in the size is a 10% error in the yield. See what can I build on my property.

Subdivision

Whether an erf can be divided depends on the minimum erf size for the area. An erf that is 1,950 m² where the minimum is 1,000 m² cannot be split into two complying portions; one that is 2,050 m² might be. A few square metres either way changes the answer. See can I subdivide my property.

Second dwellings

Provisions for a second dwelling often depend on erf size. See granny flat rules.

Rates and running costs

Larger erven generally carry higher valuations, and more garden and boundary to maintain and secure.

Minimum erf size

The minimum erf size is the smallest erf the land use scheme allows in a given area or zone, sometimes expressed as a density of one dwelling per a stated number of square metres. It is the key control on subdivision in low-density areas.

It varies across Johannesburg. Established low-density suburbs tend to have larger minimums; areas where the City supports densification have smaller ones. Never assume the minimum from another suburb.

Shape matters as much as size

Two erven of 1,000 m² can be worth very different amounts.

• Regular rectangles use land efficiently.
• Narrow erven lose a large share to side building lines.
• Panhandles include a driveway strip that counts in the area but cannot be built on.
• Triangles and irregular shapes leave awkward corners.
• Steep slopes reduce usable land and raise building costs.

Always look at the boundary on the map, not only the number. See check a property boundary.

When the erf size and the advert disagree

Common explanations:

• the advert quoted floor area, not land;
• the figure was rounded generously;
• an adjoining erf or a fenced-in strip was included by mistake;
• old measurements were converted from square feet or another unit with an error;
• the property was subdivided or consolidated and the advert uses the old figure.

Rely on the registered size. If the difference matters to your offer, raise it before you sign.

Usable area versus registered area

Even the correct erf size overstates what you can use. Deduct:

• building restriction areas along each boundary;
• servitudes for services or access. See survey diagrams and servitudes;
• floodline areas. See floodline check;
• land too steep or awkward to build on.

Developers call what remains the net developable area. On a small erf it can be surprisingly little.

Frequently asked questions

How do I convert erf size to acres? One acre is about 4,047 m², so 1,000 m² is roughly a quarter of an acre.

Can my erf size change? Only through a formal process: subdivision, consolidation, or the registration of land taken for a road.

Is the erf size on my rates account reliable? It normally reflects the registered extent. Confirm against the title deed or diagram for anything important.

The bottom line

Erf size is the base figure for price comparison, development yield and subdivision. Look it up, check it against the boundary, and work from the registered extent — not the advert.

Look up an erf's size and details.

This is general information, not legal or town-planning advice. Confirm the registered extent against the title deed and survey diagram before relying on it.